Inorganic chemistry of the main group elements vol 5

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A Specialist Periodical Report

Inorganic Chemistry of the Main-Group
Elements
Volume 5

A Review of the Literature Published between October 1975
and Septern ber 1976

Senior Reporter
C. C. Addison
Reporters
M. G. Barker
G. Davidson
M. F. A. Dove
P. G. Harrison
P. Hubberstey
N. Logan
D. B. Sowerby
All of: Department of Chemistry, University of Nottingham

The Chemical Society
Burlington House, London W I V OBN

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British Library Cataloguing in Publication Data
Inorganic chemistry of the Main-group elements.
(Chemical Society; Specialist periodical reports).
VOl. 5
1. Chemistry, Inorganic 2. Chemical elements
I. Addison, Cyril Clifford 11. Series
546
QD151.2
72-95098

ISBN 0-85 186-792-8
ISSN 0305-697X

Copyright @ 1978
The Chemical Society

All Rights Reserved
No part of this book may be reproduced or transmitted
in any form or by any means-graphic, electronic,
including photocopying, recording, taping or
information storage and retrieval systems - without
written permission from The Chemical Society

Filmset in Northern Ireland at The Universities Press (Belfast) Ltd, and printed at The Pitman
Press (Bath) Ltd.


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Preface
It has again been possible, in Volume 5 , to find authors for all chapters from
amongst the inorganic chemists in the University of Nottingham, and the Senior
Reporter would like to express his appreciation of the hard work to which they
were prepared to commit themselves, and of the enthusiasm which they have
shown. Because of financial pressures, we were called upon to produce a volume
only two-thirds the length of Volume 4. The shorter the volume the more difficult
becomes the task of choosing amongst the large number of worth-while research
papers published during the year. Readers will detect a further move in the
direction of structure and reactivity as against purely physical properties; for
example, Chaper 4 no longer includes cover of binary and ternary intermetallic
phases, which have been included in earlier volumes. All authors regret that much
good work which merited mention has had to be omitted purely because of space
limitation. Selection has to be based on originality and novelty, but also on the
need to present a readable account, and thus to include reference to all published
papers on any chosen theme. In this difficult task the authors have found that the
opportunity to work as a team, and to maintain day to day discussion on possible
overlap between chapters, has been of considerable advantage.

C . C. ADDISON

.I.

1ll


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contents
Chapter 1

Elements of Group I
By P. Hubberstey
1 Introduction

1

2 The Alkali Metals as Solvent Media

1

3 Metallic Solutions and Intermetallic Compounds

6

4 Solvation of Alkali-metal Cations

7

5 Simple Compounds of the Alkali Metals
Hydrides
Oxides, Hydroxides, Sulphides, etc.
Halides
Molten Salts
Halides
Nitrates

6 Compounds of the Alkali Metals containing Organic
Molecules or Complex Ions
Radical-anion Salts
Crown and Cryptate Complexes
Lithium Derivatives
Sodium Derivatives
Potassium Derivatives
Rubidium and Caesium Derivatives

Chapter 2

1

Elements of Group I I

11
11
12
14
15
15
18
19
19
21
27
29
31
33

35

By P. Hubberstey
1 Introduction

35

2 Alloys and Intermetallic Compounds
Transition Metals and Rare Earths
Main-Group Elements

36
36
36

3 Binary Compounds
Oxides, Sulphides, and Related Species
Halides

38
38

4 Ternary Compounds
Hydrides
Oxides
Halides

40

40

40
40

41
V


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Contents

vi

5 Compounds containing Organic or Complex Ions
Beryllium Derivatives
Magnesium Derivatives
Calcium Derivatives
Strontium and Barium Derivatives

54

Chapter 3 Elements of Group 111
By

43
43
45
49
52

G. Davidson

1 Boron
Boranes
Borane Anions and Metallo-derivatives
Carba- and other Non-metal Hetero-boranes
Metallo-hetero boranes
Compounds containing B-C Bonds
Aminoboranes and other Compounds containing
B-N Bonds
Compounds containing B-P or B-As Bonds
Compounds containing B-0 Bonds
Compounds containing B-S or B-Se Bonds
Boron Halides
Boron-containing Heterocycles
Boron Nitride, Metal Borides, etc.

2 Aluminium
General
Aluminium Hydrides
Compounds containing Al-C
Compounds containing Al-N
Compounds containing A1-0
Aluminium Halides

Bonds
Bonds
or Al-Se

Bonds

54
54
55
59
65
72
73
76
77
80
81
83
88
89
89
89
90
91
92
96

99
3 Gallium
Compounds containing Ga-N,
Ga-P,
or
99
Ga-As Bonds

Compounds containing Bonds between Gallium and
100
Atoms of Elements of Group VI
Gallium Halides
102
4 Indium
General
Compounds containing Bonds between Indium and
Atoms of Elements of Group VI
Indium Halides

103
104

5 Thallium
Thallium(II1) Compounds
Thallium(1) Compounds
Other Thallium Compounds

106
106
107
108

103
103


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Contents

Chapter 4

vii

Elements of Group IV

109

By P. G. Harrison

Chapter 5

1 Carbon
Carbon Allotropes
Chemical Reactions
Intercalation Compounds
Carbon Compounds
Hydrocarbons
Halogen Derivatives
Oxygen and Sulphur Derivatives
0ther Derivatives

109
109
111
113
114
114
114

116
118

2 Silicon, Germanium, Tin, and Lead
Hydrides of Silicon, Germanium, and Tin
The Metal(w) Oxides and Related Oxide Phases
Simple Oxides
Silicates, Germanates, and Related Materials
Molecular Silicon(1v)-, Germanium(w)-, Tin(rv)-, and
Lead (Iv)-Ox y gen Derivatives
Halogen Derivatives
Sulphur, Selenium, and Tellurium Derivatives
Sulphides, Selenides, and Tellurides
Molecular Sulphur and Selenium Compounds
Nitrogen and Phosphorus Derivatives
Derivatives with Bonds to Main-Group Metals
Derivatives with Bonds to Transition Metals
Bivalent Derivatives
Subvalent Chemistry

118
118
119
119
122

Elements of Group V

125
134

141
141
142
144
145
150
157
172

173

By N. Logan and D. B. Sowerby
1 Nitrogen
Elemental Nitrogen
Reactions of N2
Complexing of N2
Nitrides
Bonds to Hydrogen
Ammonia
The Ammonium Ion
Hydroxylamine
Bonds to Nitrogen
The N2H2Molecule
Hydrazine
Azides
Bonds to Oxygen
General

173
173

173
175
175
177
177
178
179
179
179
180
180
181
181


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...

Contents

Vlll

Nitrogen($ Species
Nitric Oxide
Nitrogen(xI1) Species
NOZ-NZOd
Nitric Acid
Nitrates
NO,’ Salts

Bonds to Fluorine
Bonds to Bromine and Iodine
2 Phosphorus

Phosphides
Compounds containing P-P Bonds
Bond to Boron
Bonds to Carbon
Phosphorus(xI1) Compounds
Phosphorus(v) Compounds
Bonds to Silicon, Germanium, or Tin
Bonds to Halogens
Phosphorus(n1) Compounds
Phosphorus(v) Compounds
Bonds to Nitrogen
Phosphorus(n1) Compounds
Phosphorus(v) Compounds
Compounds containing P-N Rings
Compounds containing Other Ring Systems
Bonds to Oxygen
Compounds of Lower Oxidation State
Phosphorus(v) Compounds
X-Ray Diffraction Studies
Phase Studies
Mono-, Di-, and Poly-phosphates
Bonds to Sulphur or Selenium

181
181
182

183
184
184
187
187
187
188
188
188
190
191
191
193
195
196
196
198
200
200
202
205
212
213
213
214
216
216
217
218

3 Arsenic
Arsenides
Bonds to Carbon
Bonds to Halogens
Bonds to Nitrogen
Bonds to Oxygen
Bonds to Sulphur or Selenium

220
220
221
222
223
223
225

4 Antimony

226

Antimony and Antimonides
Bonds to Carbon
Bonds to Halogens
Antimony(xI1) Compounds
Antimony(v) Compounds
Bonds to Oxygen
Antimony(II1) Compounds

226
227

228
228
229
23 1
23 1


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ix

Contents
Antimony(v) Compounds
Bonds to Sulphur
5 Bismuth

Chapter 6

Elements of Group VI

231
232
233

234

By M. G. Barker

Chapter 7

1 Oxygen

The Element
Hydrogen Peroxide and Hydrogen-Oxygen Species
2 Sulphur
The Element
Sulphur-Halogen Compounds
Sulphur-Oxygen-Halogen Compounds
Sulphur-Nitrogen Compounds
Linear Molecules
Polymeric Sulphur Nitride
Cyclic Compounds
Sulphur-Oxygen Compounds
Oxyanions of Sulphur
Sulphides
Hydrogen Sulphide
Polysulphides
0ther Sulphides
3 Selenium
The Element
Selenium-Halogen Compounds
Selenium-Oxygen Compounds
Metal Selenides
Other Compounds of Selenium

234
234
235
237
237
237
241

242
242
244
245
250
253
255
255
257
257
259
259
259
260
261
263

4 Tellurium
The Element
Tellurium-Halogen Compounds
Tellurium-Oxygen Compounds
Tellurides
Other Compounds containing Tellurium

263
263
264
267
268
270

The Halogens and Hydrogen

27 1

By M. F. A. Dove
1 Halogens
The Elements
Halides
Interhalogens and Related Species
Oxides, Oxide Halides, and Oxyanions
Hydrogen Halides

271
271
273
276
28 1
284


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Contents

X

2 Hydrogen
Hydrogen-bonding
Protonic Acids
Miscellaneous

Chapter 8 The Noble Gases

286
286
289
290

292

By M. F. A. Dove
1 The Elements

292

2 Krypton(n) and Xenon(n)

292

3 Xenon(rv)

295

4 Xenon(w)

295

Author Index

297

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1

Elements of Group
BY P. HUBBERSTEY

1 Introduction
The definition of the limits of the literature search pertinent to the present Report
is complicated by the extensive role of the alkali metals as simple counter-cations.
In general, papers have been abstracted which are relevant to a number of broad
subject groups in which the role of the alkali metals is unique. Consequently, the
format of this Chapter is such that the inorganic chemistry of the alkali metals is
considered collectively in sections which reflect topics presently of interest and
importance.
For certain topics (e.g. cation solvation, molten salts, crown and cryptate
complexes), the chemistry of the Group I and I1 metals is closely ipterwoven; in
these cases, the data abstracted are considered once only in the relevant section in
this Chapter.
The extraction of alkali-metal cations from salt solutions into organic solvents
has been the subject of four
The ion [.rr-3-1,2-B,C2Hl,]Cohas been
proposed as a nearly ideal hydrophobic anion for extraction of M' ions into
C,H,NO, uia formation of ion pairs.' Li' has been selectively extracted from
nearly neutral aqueous solutions of alkali-metal salts via the formation of the
trioctylphosphine adduct of a lithium chelate of fluorinated /3 -diketones; although
high separation factors were obtained from Na', K', Rb', and Cs+, selectivity
from the alkaline-earth-metal cations was found to be poor.* The extraction of

M' into PhNO, and MeNO, using hexafluoroacetylacetonate has also been
in~estigated.~'~
Dissociation constants of the alkali-metal enolates were determined, the extent of association of enolate ion with enol to give a dimeric ion was
deduced, and the latter's formation constant calculated.

2 The Alkali Metals as Solvent Media
The role of liquid sodium as a heat-exchange medium in the fast breeder reactor,
and that of liquid lithium as a prime candidate far use as the blanket medium in a
deuterium-tritium-fuelled thermonuclear reactor, has maintained interest in the
solution chemistry of these liquid metals.
*

J. Rais, P. Selucky, and M. Kyrs, J. Inorg. Nuclear
F. G. Seeley and W. H. Baldwin, J. Inorg. Nuclear
S. Tribalat and M. Grall, Cornpt. rend., 1976, 282,
S . Tribalat and M. Grall, Compt. rend., 1976, 282,

1

Chem., 1976, 38, 1376.
Chem., 1976, 38, 1049.
C, 457.
C , 539.


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2

Inorganic Chemistry of the Main-Group Elements

Phase equilibria for Li-Li3N dilute solutions have been investigated by two
independent groups of authors.'-'
Pulham et ~ 1 . ' have
~ ~ determined the
hypoeutectic and hypereutectic liquidi by thermal5 and by electrical resistance6
methods, respectively. The freezing point of Li (453.64 K) is depressed by 0.25 K
to 453.39 K at the eutectic composition 0.068 mol YO N. The depression was used
to calculate the solid solubility of Li,N in Li (0.024molYoN) at the eutectic
temperature.' The solubility of Li3N in liquid Li increases smoothly from the
eutectic to 2.77 mol % N at 723 K.6 Over a wide temperature range, the data can
be represented by equation (1). These latter data are corroborated by those of
Veleckis et aL7 [equation (2)], who used a direct sampling technique. This
agreement resolves the problem of the earlier inconsistent data' referred to in the
previous Report.' Veleckis et uL7 also measured the equilibrium nitrogen pressure
over solid Li,N at temperatures between 933 and 1051 K. From a thermodynamic
analysis of the solubility and decomposition data, the standard free energy of
formation of solid Li3N (AGy/kJ mol-l) was estimated to be 138.9 X
T/K 163.6. For dilute solutions of Li3N in Li, the Sieverts law constant (Ks/atm-1'2=
xLi3N P-''~) is given by -13.80+ 14590 (T',K)-'. The melting point of Li,N was found
to be 1086 K, in good agreement with the previously reported value of 1088 K.7
10gloXN= 1.168-2036(T/K)-'

(473 s T/Ks708)

(1)

10g10XL13N
= 1.323 - 2107(T/K)-'

(468 G T/Ks714)

(2)

Phase equilibria of Li-LiH and Li-LiD dilute solutions have also been studied
by Pulham et a1.5T6~'0*'1
The maximum depression of the freezing point of Li by
LiH5 (LiD)" is 0.08K (0.075K), corresponding to a eutectic composition of
0.016 mol%H (0.013 mol% D). These data, which indicate negligible solid solubility of the salts in Li, have been used to show that both hydrogen and deuterium
dissolve in liquid Li as monatomic solute species." Typically, the depression
caused by small LiH concentrations (Figure 1) follows quite closely the line
derived theoretically for monatomic solutes. The theoretical line for a diatomic
species is included in the Figure for comparison. The solubilities of LiH6 and of
LiD" in liquid Li have been determined by electrical resistance methods at
temperatures up to 824 K (5.68 mol%H), and 729 K (2.63 mol%D), and can be
represented over a considerable part of the temperature range by equations (3)
and (4), respectively. The hydrogen-deuterium isotope effect has been discussed
and the experimental data have been extrapolated to predict the behaviour of
tritium in liquid Li."."
loglOXH=1.523-2308(T/K)-l

( 5 2 3 s T/KS775)

(3)

10gloxD= 2.321 - 2873(T/K)-'

(549 C T/K S 724)

(4)

P. Hubberstey, R. J. Pulham, and A. E. Thunder, J. C. S. Faraday I, 1976, 72, 431.

' P. F. Adams, M. G. Down, P. Hubberstey, and R. J. Pulham, J. Less-Common Metals, 1975,42,325.

lo

l1

R. M. Yonco, E. Veleckis, and V. A. Moroni, J. Nuclear Materials, 1975, 57, 317.
P. F. Adams, P. Hubberstey, and R. J. Pulham, J . Less-Common Metals, 1975, 42, 1.
R. J. Pulham, in 'Inorganic Chemistry of the Main-Group Elements' (Specialist Periodical Reports),
ed. C. C. Addison, The Chemical Society, London, 1976, Vol. 4, Ch. 1.
P. F. Adams, P. Hubberstey, R. J. Pulham, and A . E. Thunder, J. Less-Common Metals, 1976, 46,
285.
P. Hubberstey, P. F. Adams, R. J. Pulham, M. G. Down, and A. E. Thunder, J. Less-Common
Metals, 1976, 49, 253.


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3

Elements of Group I

r

'. -Diatomic
453955

soiute species

'\Monatomic solute species

0

0.01
0.02
Concenhtion (mol .I.

093
H)

Figure 1 Depression of the freezing point of lithium by small concentrations of hydrogen,
showing evidence for monatomic solute species
(Reproduced by permission from J. Less-Common Metals, 1976, 49, 253)

New solubility data for NaH in liquid Na have been determined by Whittingham" in a detailed study (610-677K)
of the thermodynamic and kinetic
properties of the liquid Na-H, system. Comparison with some previous data has
been effected and a composite solubility equation (5) formulated.
logloxH= 1.818 - 3019(T/K)-'

(435 4 T/K C 673)

(5)

These new solubility data for hydrogen isotopes have been collated and
compared to the corresponding solubilities in NaK and K;l' surprisingly, hydrogen is least soluble in sodium.
Solubility data have been used6'10'11 to determine solvation enthalpies, U,,
[defined as in equation (6)] for N3-, 0'-,
H-, and D- in Li and for H- in Na and

K. The values of U, are collected in Table 1. Those for H- and D- in Li are
lower than those for 02-and N3- by factors of ca. 22 and 3', respectively,
corresponding to increasing U, with increasing charge of solute. Those
for H- in Li, Na, and K are very similar, that in Li being the greatest."
Solvation enthalpies have been derived13 in ab initio M.O. calculations of solvation clusters in Li and Na. By comparison with experimental data, the best model
was deduced to be that of a tetrahedral solvation sphere of cations supplemented
by a further metal tetrahedron positioned on the three-fold axes of the first
solvation sphere. Other incidental results to emerge from the calculations are the
effective radii for Li (0.1675 nm), Na (0.1715 nm), and H (0.0525 nm in Li and

Table 1 Solvation enthalpies for non-metal solutes in liquid alkali metals
Solvent
Solute
UJkJ mol-'

'*
l3

Potassium Sodium
Lithium
Lithium
Hydrogen Hydrogen Hydrogen Deuterium
-362
-365
-427
-413

Lithium
Oxygen
-1960

A. C. Whittingham, J. Nuclear Materials, 1976, 60, 119.
A. Mainwood and A. M. Stoneham, J. Less-Common Metals, 1976, 49, 271.

Lithium
Nitrogen
-3473


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4

Inorganic Chemistry of the Main-Group Elements

0.0535 nm in Na) and the effective charges on the H (-0.45 in Li and -0.25 in
~a).l~
U

X”-(g) - t - M a X ” - ( M )
(6)
The chemistry of liquid alkali metal-hydrogen solutions has been surveyed.”
Whereas hydrogen and nitrogen act independently in Li at 693 K, hydrogen and
oxygen interact in Na at 673 K, according to equilibrium (7). Hydrogen-xygen
interactions in the other alkali metals are also considered and rationalized in
terms of the enthalpy changes of the corresponding solid-state reaction. Furthermore, Y has been shown to react with hydrogen in Li at 673 K to form a mixture
of Y(H) solid solution and YH, according to reaction (8).11
02-+ H-

+ 2eLi(H) + Y -+ Li + Y(H) + YH,

OH-

(7)
(8)

Enrichment of deuterium in the gaseous phase above dilute Li-LiD solutions
(x, = lop5) has been observed by Ihle and Wu14 at temperatures above 1240 K.
This supports the contention that deuterium can be removed from highly dilute
solutions in Li by distillation. The results are of importance in the context of the
technology of thermonuclear reactors and have been extrapolated to Li-LiT
solutions.l4
Several papers pertinent to the elucidation of the corrosive properties of very
dilute solutions of non-metals in liquid alkali metals have been p ~ b l i s h e d . ’ ~ - ~ ~
The corrosion of V,15 Nb,15 Ta,15 Mo,16 and W16 plates suspended in dynamic
liquid sodium, containing more than 5 p.p.m. oxygen, has been examined at
873 K; the products were analysed through a matrix of Na by X-ray diffraction
techniques. The ternary oxides Na,VO, and NaVO, were formed on V, together
with a V(0) solid ~olution.~’
For Nb and Ta, only a single ternary oxide Na,MO,
(M=Nb or Ta) was observed, together with a M(0) solid
Although
corrosion of Mo was found to be independent of oxygen concentration, no ternary
oxide products being observed, that of W was found to be strongly influenced by
initial oxygen concentration in the Na. At low oxygen levels, the cubic phase
Na,WO, was identified; at very high oxygen levels in static Na, however, the
orthorhombic phase Na6WO6 was observed. Inclusion of labile carbon in the
system containing Mo caused the formation of Mo2C.16 The closely related
solid-state reaction of Na,O with Mo and W under vacuum gave the ternary
phases Na,Mo05 and Na6WO6, respectively, together with unreacted refractory
metal and Na vapour.16

Barker and H00per’~have reinvestigated the products of the reaction of liquid
Na with CrO, at temperatures up to 873 K; CrO,, Cr203,and Na,CrO, were also
studied as substrates. The ternary oxide NaCrO, is found in each case in which
reaction took place. The previously accepted reaction product, Na,Cr03, was not
formed; the error has been rationalized in terms of the experimental procedure,
and improved techniques have been deve10ped.l~Gellings et ~ 1 . ’ ’ have also studied
l4

l5
l6

l7

’’

H. R. Ihle and C. H. Wu, J. Phys. Chem., 1975, 79, 2386.
M. G. Barker and C. W. Morris, J. Less-Common Metals, 1975, 42, 229.
M. G. Barker and C. W. Morris, J. Less-Common Metals. 1976, 44, 169.
M. G . Barker and A. J. Hooper, J. C. S. Dalton, 1976, 1093.
H. van Lith, E. G. van den Broek, and P. J. Gellings Znorg. Nuclear Chem. Letters, 1975, 11, 817.


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Elements of Group I

5

the reaction of CrO, with liquid Na, their results corroborating the identification
of NaCrO, as product. The product of these reactions, NaCrO,, together with the
other ternary oxides Na,CrO, and Na,CrO,, has been prepared by Barker et ul.19

by the reaction of Na,O and Cr203or Cr, and it has been characterized by X-ray
powder difTraction techniques. NaCrO, decomposes reversibly to the simple
oxides at cu. 1068K.l’
The reaction of pure liquid Li with MO, (M=Ti, Zr, Hf, or Th) has been
shown to follow thermodynamic predictions.20 TiO, and ZrO, give rise to Li,O
and the appropriate transition metal; HfO, yields Hf metal, Li20, and a tetragonal phase, which may be the ternary oxide LiHfO,; Tho, does not react.
Reaction with liquid Li doped with dissolved nitrogen, however, converts all four
oxides, in differing degrees, into either the mononitride or a ternary nitride Li2MN2
(M = Zr, Hf, or Th).20
Liquid K reduces NiO to Ni metal at 458 K with the concomitant formation of
the ternary oxides K,NiO, and K,NiO, ; thermomagnetic analysis indicates that
the reaction occurs in a single step.21K2Ni0, was also prepared by the reaction of
equimolar quantities of K,O and NiO; K,NiO, was produced by the reaction of
K,O and NiO in 0, or by heating K,NiO, in a stream OP 0,.
The reaction between Ba and N, in liquid Na has been investigated at
573 K.22923Solubility studies,, showed that the reaction of a 4.40mol YO Ba
solution occurs in two stages; (i) dissolution of N2 (N, is insoluble in pure liquid
Na), and (ii) precipitation of Ba,N, the initial product of the reaction. The
occurrence of these two processes is reflected in the resistivity studies2, effected
on a number of Na-Ba solutions (between 0.34 and 6.89 mol YO Ba). The extent
of the solution process was found to be a linear function [equation (9)] of the initial
Ba concentration, the solubility limit corresponding to an overall reaction composition approximating to Ba,N. This ratio, and the decrease in resistivity which
invariably occurred during the solution process, leads to the concept of strong
preferential solvation of the nitride ion by Ba cations, perhaps in the form of a
‘Ba,N’ solvated unit.,,
xN = 0 . 2 5 ~ ~(0
~< xBa < 0.0689)

(9)

The reaction of C,H, with liquid K has been studied in the range 5 0 3 - 6 7 1 K.,,
At low temperatures, self -hydrogenation occurs precisely according to equation
(10). The surface reaction is explained by dissociative adsorption of C2H4 into H
adatoms, which are subsequently employed in hydrogenation. With increasing
temperature, progressively less C2H6 is produced, which is attributed to the loss of
H from the surface by solution in the metal.,,

l9
20

21
22

23
24

M. G. Barker and A. J. Hooper, J. C. S. Dalton, 1975, 2487.
M. G. Barker, I. Alexander, and J. Bentham, J. Less-Common Metals, 1975,42, 241.
M. G. Barker and A. P. Dawson, J. Less-Common Metals, 1976, 45, 323.
C. C. Addison, R. J. Pulham, and E. A. Trevillion, J. C. S. Dalton, 1975, 2082.
C. C. Addison, G. K. Creffield, P. Hubberstey, and R. J. Pulham, J. C. S. Dalton, 1976, 1105.
G. Parry and R. J. Pulham, J. C. S. Dalton, 1975, 2576.


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6

Inorganic Chemistry of the Main-Group Elements

3 Metallic Solutions and Intermetallic Compounds

The nature of the bonding in intermetallic phases has been
and an
attempt has been made to demonstrate qualitatively the dependence of both the
number of phases in a binary system and their relative thermal stabilities on the
electronic configurations of the component atoms. Particular attention has been
devoted to compounds of the alkali metals with Hg,25Sn,26Pb,25Sb?' and BiZ5
The preparation of the novel compounds K2Cs and K7Cs6by precipitation from
solid K-Cs solutions at temperatures below 183 K has been reported.27 Structural
analysis has shown that K2Cs (a = 0.9065, c = 1.4755 nm at 178 K) is isotypic
with the hexagonal Laves phase Na2K, whereas K7Cs6 ( a = 0.9078, c = 3.2950 nm
at 178 K) forms hexagonal crystals with a novel kind of Frank-Kasper structure.
Although the K atoms in K7Cs, are sited in two 12-co-ordination polyhedra, the
Cs atoms occupy one of four sites with 14-fold, 15-fold (X2), and 16-fold
co-ordination. The K * - K, Cs - - Cs, and K - - - Cs distances vary from 0.454 to
0.461, from 0.501 to 0.546, and from 0.466 to 0.5741m.~~
The Li-In phase diagram has been exhaustively re-examined by Alexander et
~ l . , ' ~using thermal and X-ray diffraction analysis. The work has confirmed the
liquidus data of Grube and Wolf29 and delineated .the solid-state relationships.
Eleven new phases (Table 2), together with the previously known LiIn phase
(which extends from ca. 46 to between 55 and 63 mol% Li, depending on
temperature), have been observed. The discovery of new phases, of which only
five are stable at room temperature, has removed the apparent anomaly between
the Li-In and the Li-Ga and Li-Tl systems. The solid solubility of Li in In is low
(ca. 1.5 mol O h Li at 432 K) and that of In in Li is very
Intermetallic phases of the Li-Pd3' and Li-Pt31 systems have been synthesized

Table 2 Intermetallic phases of the Li-In system2'
Phase

I.L

Model
fomula
LiIn
Li71n,
Li21n
Li51n2
Li,In,
Li731n27
Li,,In,
Li,In
Li,In
Li,In
Li61n

Y

LiJn

P
Y

s
&

5
rl

e

L
K

A

a

Melting point;
peritectoid decomposition;
phase transformation

"

26
27

'*
29
30
31

Cornpositionlmol% Li
derived
observed
50.0
46.5-63.0
63.6
63.6
66.7
66.8

71.5
71.8
72.8
71.9
73.0
73.4
75.0
75.8
80.0
80.7
80.0
80.7
85.7
85.5
92.3
92.6

Phase transformation
temperatures (approx.)/K
903"
583'
743'
353d
670'
353'
61gd
698"
60gd
658b
686"

583'
583"
673'
39gd
573"
413d
533"

peritectic decomposition;

eutectoid formation;

V. I. Kober and I. F. Nichkov, Russ.J. Phys. Chem., 1975,49, 829.
V. I. Kober and I. F. Nichkov, Russ. J. Phys. Chem., 1975, 49, 962.
A. Simon, W. Bramer, B. Hillenrotter, and H.-J. Kullman, 2. anorg. Chem., 1976, 419, 253.
W. A. Alexander, L. D. Calvert, R. H. Gamble, and K. Schinzel, Canad. J. Chem., 1976,54,1052.
G. Grube and W. Wolf, 2.Electrochem., 1935, 41, 675.
J. H. N. van Vucht and K. H. J. Buschow, J. Less-Common Metals, 1976, 48, 345.
W. Bronger, B. Nacken, and K. Ploog, J. Less-Common Metals, 1975, 43, 143.


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Elements of Group I

7

and their structures elucidated; pertinent structural data for seven Li-Pd phases
(including Li,Pd and LiPd), as determined in X-ray diffraction studies, and for
Li,Pt and LiPt, as determined using neutron-diflraction techniques, are collected
in Table 3.

Table 3 Pertinent structural parameters for intermetallic phases in the li-Pd and
Li-Pt systems
Phase

LiPd,
LiPd,
LiPd"
LiPd
Li,Pd

Li,Pd
Li,,Pd,
Li, Pd"
(6 < x < 10)
LiPt
Li,Pt
a

Space group
Fm3m
hexag. P

Structure type

LiPt,

-

P6
Pm3m

P6Immc
Fm3m
143d

LiRb
CSCl
AIB,
BiF,

cubic
hexag.
-

AlB,

Cu,,Si,

alnm
0.7660
0.3836
0.2977
0.4227
0.6187
1.0676
1.9009
1.9347
0.2728
0.4186

{

clnm
0.4336
0.4280
0.4131
0.2732
-

-

0.4226
0.2661

Ref.
30
30
30
30
30
30
30
30
30
30
31
31

LiPd and Li,Pd exhibit wide homogeneity ranges

Thermodynamic properties of liquid Li-T132 and of liquid Na-X33 (X = Cd, Hg,

In, TI, Sn, Pb, Sb, Bi, S, Se, or Te) have been studied. The unsymmetrical form
of the nature of the dependence on concentration of the thermodynamic characteristics of the Li-TI system, which exhibits negative deviations from Raoult's
Law, is thought to be consistent with the equilibrium diagram.32The dependence
on concentration of the entropy of mixing in the Na-X systems is S-shaped, the
point of inflexion corresponding to formation of intermetallic
This
behaviour is attributed to a high degree of short-range order in the liquid, and of
partial ionic character of the bonds in these intermetallic compounds. Short-range
order has also been studied in liquid Li-Pb solutions by neutron-diffraction
t e c h n i q ~ e s The
. ~ ~ data indicate a preference for unlike nearest neighbours; this is
manifest in a reduction of distance between unlike neighbours (0.295 nm) as
compared with the mean distances between the pure components (Li - - * Li =
0.300 nm; Pb - Pb = 0.340 nm). It has been suggested that the short-range order
is probably due to salt-like Li - - Pb bonding. No evidence for the existence of
isolated LLPb clusters was obtained; indeed, in liquid Li,Pb, each Pb atom is
surrounded by ca. 10 Li atoms.,,

--

-

4 Solvation of Alkali-metal Cations

The majority of data published on the solvation (both aqueous and non-aqueous)
of alkali-(and alkaline-earth-)metal cations is of but peripheral interest to the
inorganic chemist. Consequently, the papers abstracted for this section of the
Report are quite selective, dealing principally with the structural and spectroscopic properties of these solutions.
32

33
34

S. P. Yatsenko and E. A. Saltykova, Russ. J. Phys. Chem., 1975, 49, 292.
A. G. Morachevskii, E. A. Maiorova, and A. I. Demidov, Russ.J. Phys. Chem., 1975, 49, 1093.
H. Ruppersberg and H. Egger, J. Chem. Phys., 1975, 63, 4095.


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8

Inorganic Chemistry of the Main- Group Elements

As a starting point in a theoretical study of ionic solutions, the complex H,OLi'-F has been ~ o n s i d e r e dAnalysis
.~~
of the stabilization energies of some 250
geometrical configurations reveals the existence of at least three possible structures: (i) the Li-F-H,O structure that has C,, symmetry; (ii) a second Li-F-H,O
structure with the F forming a hydrogen bond (with a hydroxy-group); and (iii)
the F-Li-H20 structure that has C,,
A model for an ion immersed in a dielectric medium as a spherical charge
surrounded by a region of dielectric gradient has been applied to structured
solutions of strong binary electrolyte^.^^ In the case of alkaline-earth-metal
halides and nitrates, the results show excellent agreement with experimental data
up to concentrations of 2 or 3 mol l-1.36Changes in cation polarizability observed
on hydration have been described by a model which attributes the changes solely
to solvent p e r t ~ r b a t i o n Hydration
.~~
structures for alkali-metal cations have been
generated from the results of a number of energy ~ a l ~ ~ l a t iFor
o n Li'

~ . ~and
~ Na'
a tetrahedral inner solvation sphere is the most stable configuration. For K+, Rb',
and Csf, the energy differences between structures are so small that it is
impossible to predict with certainty the most stable c~nfiguration.~'CND0/2
calculations have also been effected for solvation of, inter a h , Li' and Na', by
MeOH.39 The results are compared with experimental data (only partial agreement is achieved) and with similar calculations for solvation by water. Thermodynamic functions for hydration of alkali-metal cations have also been determined:
and the effects of solvation on the conductivity of concentrated electrolyte solutions studied theoretically and e~perimentally.~~
The structures of these ionic solutions have been studied, using X-ray difb-action,42*43n.m.r.,4448 and ultrasonic49 techniques. X-Ray diffraction measurements of aqueous NaI
showed that the Na' ion is bonded to cu. four
water molecules at a Na'. - - 0 distance of ca. 0.24 nm. Similar experimental data
for aqueous CaBr,
can be rationalized with both six- and eight-fold
co-ordinate Ca2+ions. In both solutions, the halide ion is approximately octahedrally c o - ~ r d i n a t e d . ~ ~ ' ~ ~
of aqueous LiIO, solutions containing
Studies of 7Li n.m.r. relaxation
added iodic acid or iodates have established that, up to concentrations of LiI03 of
3 mol l-l, the 10, ion does not substitute in the first hydration shell of the Li' ion.
35
36

37

38
39
40

41
42

43
44

45

46
47
48
49

J. W. Kress, E. Clementi, J. J. Kozak, and M. E. Schwartz, J. Chem. Phys., 1975, 63, 3907.
L. W. Bahe and D. Parker, J. Amer. Chem. SOC.,1975, 97, 5664.

H. Coker, J. Phys. Chem., 1976, 80, 2084.
K. G. Spears and S. Y . Kim, J. Phys. Chem., 1976, 80, 673.
M. Salomon, Canad. J. Chem., 1975, 53, 3194.
R.Jalenti and R. Caramazza, J. C . S . Faruday I, 1976, 72, 715.
D.E. Goldsack, R. Franchetto, and A. Franchetto, Canad. J. Chem., 1976, 54, 2953.
M. Maeda and H. Ohtaki, Bull. Chem. SOC.Japan, 1975, 48, 3755.
G. Licheri, G. Piccaluga, and G. Pinna, J. Chem. Phys., 1975, 63, 4412.
L. A . Arazova, N. V. Bryushkova, E. E. Vinogradov, I. M. Karataeva, and R. K. Mazitov, Russ. J.
Inorg. Chem., 1976, 21, 3.
W. J. deWitte, R. C. Schoening, and A. I. Popov, Inorg. Nuclear Chem. Letters, 1976, 12, 251.
J. W. Akitt and R. H. Duncan, J. C. S. Furuday I, 1976, 72, 2132.
L. Simeral and G. E. Maciel, J. Phys. Chem., 1976, 80, 552.
M. C. R. Symons, Spectrochim. Actu, 1975, 31A, 1105.
G . A. Ivashina, T. S. Kuratova, M. 0. Tereshkevich, and V. G. Korovina, Russ. J. Phys. Chem.,
1975, 49, 1185.

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Elements of Group I

9

133
Cs n.m.r. data4’ for caesium salts in H,O and in various non-aqueous solvents
have been interpreted in terms of the formation of contact ion-pairs, even in polar
solvents of high donicity. The large radius and concomitant low charge/surface
ratio of Cs’ make it a poorly solvated ion, and caesium salts are more liable to
form ion pairs than are Li’ or Na’
’H n.m.r. data for aqueous solutions of Be(NO,), and BeCl, have been
interpreted46 as arising from rapid proton exchange between bulk H 2 0 and H,O
in three ionic environments: (i) the cationic complex Be(H,O):’,
(ii) a second
hydration sphere oriented by the electric field of the cation, and (iii) H,O near the
anions. It has been suggested that the fact that a known tetrahydrated cation,
Be(H,O):+, gives results which are consistent with a primary co-ordination
number of 4 is a key result, and that it gives strong support to the contention,
.~~
based on similar results for M’ ions, that these are also t e t r a h ~ d r a t e d Unfortunately, in a related 2sMg F.T. n.m.r. study47of aqueous solutions of magnesium
salts, it was found to be impossible to predict, a priori, the relative importance of
the solution structures considered. The effect of temperature and of added
aprotic solvents (e.g. MeCN) on the ‘H n.m.r. spectra of H,O and MeOH
solutions containing Mg” (and A13’) have been a ~ c e r t a i n e d .The
~ ~ data are
thought to be indicative of strong secondary solvation, effected principally via
hydrogen bonding, but with a small contribution from the electrostatic effect.
An ultrasonic study of aqueous solutions of alkaline-earth-metal salts has been
~ n d e r t a k e nThe

. ~ ~ observations suggest that the stability of the solvated structures
depends on the capacity of the ions for hydration and complex formation, their
dimension, and their shape.
Ionic solvation in H,O+cosolvent mixtures has been the subject of a number of recent ~ ~ m m u n i ~ a t i o n ~Cosolvents
. ’ ~ - ~ ~ have included acetone,” formamide,’* NN-dirnethylf~rmamide,’~
NN-dimethyla~etamide,’~t-butyl alcoh01,’~
and dioxan.” Interpretation of ‘H n.m.r. data (173-303 K) for solutions of
Be(N03), in aqueous acetone solutionssohas shown that Be2+is present mainly in
the form of tetra-aquo complexes, coexisting with (probably) polymerized
hydroxo(oxo)diaquo complexes. The existence of the tetra-aquo complex has been
The
confirmed by analyses of ”0 n.m.r. spectra of aqueous Be(NO,),
formation of solvated cationic species in H20iformamide (Na+)’l and H 2 0+
DMF (Li+, Na+, K+)52 mixtures has also been investigated in a study of the
viscosities of these solutions. The interaction of lithium salts with dilute H,O+
DMA mixtures has been studied, using 13C n.m.r. technique^;'^ the results have
been interpreted in terms of the transient species Li’(H,O),DMA
and
Li+(H20)5DMA.Thermodynamic parameters for the transfer of alkali-metal salts
and into
from H 2 0 into HzO+ t-butyl alcohol (MCl; M = Li, Na, K, Rb, or C S ) ’ ~
H,O +dioxan (LiC1, NaCl, CsI)’’ mixtures have been ascertained. Similar thermodynamic data for the transfer of, inter a h , BaZ+from H,O into methanol,
50

51

*’
53

54

55

V. A. Shcherbakov and 0. G. Golubovskaya, Russ. J. Inorg. Chem., 1976, 21, 28.
J. M. McDowall, N. Martinos, and C. A. Vincent, J. C. S. Faraday I, 1976, 72, 654.
B. N. Prasad, N. P. Singh, and M. M. Singh, Indian J. Chem., 1976, 14A, 322.
M. J. Adams, C. B. Baddiel, G. E. Ellis, R. G. Jones, and A. J. Matheson, J . C. S . Faraday 11, 1975,
71, 1823.
C . F. Wells, J. C. S. Faraday I, 1976, 72, 601.
D. Feakins and C. T. Allan, J. C. S. Faraday I, 1976, 72, 314.


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Inorganic Chemistry of the Main-Group Elements

10

R

R

I

H
:

H
1

(b)

(a)

Figure 2 Solvation shells about M2+in (a) water and (b) dipolar aprotic solvents; R is
generally a methyl group
(Reproduced by permission from J. Amer. Chem. SOC.,1975,97, 3888)

hexamethylphosphoramide, acetonitrile, DMF, and DMSO have been determined.56 It has been noted that divalent cations have more than one layer of
solvent molecules in their solvation shells, for most of the solvents studied.
Whereas hydrogen bonding is thought to be the mechanism whereby hydration
shells are built up, extension to secondary shells in the case of dipolar aprotic
solvents is possible only through alternative and weaker mechanisms, such as
enhancement of the induced dipoles in the first solvation shell. A pictorial
representation of these two schemes for solvation of M2+ions is shown in Figure
2.56

The ‘effective’solvation numbers (i.e. total number of moles of solvent solvated
to one mole of solute) of NaI, KI, LiN03, LiClO,, L X (X=Cl, Br, or I), and
CaCl, and of LiC1, LiBr, LiN03, and LiC104 in MeOH have been deduced from
‘H n.m.r. studiess7 and conductivity experiment^,^^ respectively. The solvation
numbers are quite similar to hydration numbers; this observation is accepted as
evidence that both solvents bind primarily through the oxygen atom of the solvent
and not the hydroxyl proton. Furthermore, it is thought that the positive ion is
more highly solvated than the negative ion, and that M2+ions are more effectively
solvated than M’ ions.57
The conductivities of MClO, (M=Na, K, Rb, or Cs) in ethylene glycol have
been determined and the temperature coefficients of their mobilities estimated;”
the analysis of the data shows that the M’ ions are strongly solvated. Observations noted in studies of the viscosities of solutions of MI (M = Li, Na, K, Rb, or
Cs) in DMSO also indicate that solvation of M’ is important in this
56

57

”
59

6o

G. R. Hedwig, D. A. Owensby, and A. J. Parker, J. Amer. Chem. Soc., 1975, 97, 3888.
F. J. Vogrin and E. R. Malinowski, J. Amer. Chem. SOC., 1975, 97, 4876.
P. A. Skabichevskii, Russ. J. Phys. Chem., 1975, 49, 100.
R. Fernandez-Prini and G. Urrutia, J. C. S. Faraday I, 1976, 72, 637.
R. Gopal and P. Singh, Indian J. Chem., 1976, 14A, 388.


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11

Elements of Group I

The effect of triethanolamine (TEA) on the conductances of solutions of
alkali-metal 2,4-dinitrophenolates in THF has been ascertained;6' the observed
increase in conductivity in the presence of the TEA has been interpreted as due to
formation of cation-ligand and ion pair-ligand complexes. The structures of the
M'-TEA complexes (1) are assumed to be similar to that found in the Na'
solid-state complex; the three hydroxyethyl groups of the TEA are envisioned to
form a pocket of Lewis-base cations which can accept and surround the M' ions.61

0-f

(1)

1.r. and 'H n.m.r. spectra of HDO and of MeOH, at low concentration in
MeCN, propylene carbonate, 1,1,3,3-tetramethylurea, and NN-dimethylformamide containing various salts [LiClO,, LiBr, Sr(C104)2,Ca(SCN),], have
been determined at 308 f 2 K.62The results suggest the presence of solventbonded, cation-bonded, anion-bonded, and solvent-shared or solvent-separated
ion complexes.62
5 Simple Compounds of the Alkali Metals

This section deals principally with binary derivatives of the alkali metals; ternary
compounds are omitted since they are considered, as appropriate, either
elsewhere in this Report or in that covering the inorganic chemistry of the
transition metals.63Included here are subdivisions relating to hydrides, oxides and
related species, and halides. Compounds of Group IV and V non-metals are not
discussed because of the paucity of data. A separate section, entitled 'Molten
Salts', dealing with the chemistry of molten halides (and nitrates) as solvents, is
also included.
Hydrides.-Several papers describing theoretical analyses of alkali-metal hydride
molecules have been
The applicability of potential-energy functions for these molecules has been examined? and the mixing of ionic and
covalent configurations for NaH, KH (and MgH')
Possible lowenergy paths for the formation of the Li - - - H bond have been
and the spectroscopic properties of, inter alia, LiH calculated.68
The
The preparation of NaH has been the subject of two communications.69~70
62

63

64

65

67

6a
69

70

H. B. Flora and W. R. Gilkerson, J. Phys. Chem., 1976,80,679.
I. D. Kuntz and C. J. Cheng, J. Amer. Chem. Soc., 1975, 97,4852.
'Inorganic Chemistry of the Transition Elements', (Specialist Periodical Reports), ed. B. F. G.
Johnson, The Chemical Society, London.
M. M. Pate1 and V. B. Gohel, Spectrochim. Acra, 1975, 3% 855.
R. W. Numrich and D. G. Truhlar, J. Phys. Chem., 1975, 79, 2745.
W. B. England, N. H. Sabelli, and A. C. Wahl, J. Chem. Phys., 1975, 63,4596.
R. Datta, Indian J. Chem., 1976, 1 4 4 269.
A. M. Semkow and J. W. Linnett, J. C. S. Faraday Ll, 1976, 72, 1503.
J. Subrt, P. Kriz, J. Skrivanek, and V. Prochazka, Coll. Czech. Chem. Comm., 1975, 40,3766.
V. Prochazka and J. Subrt, Coll. Czech. Chem. Comm., 1976, 41, 522.


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Inorganic Chemistry of the Main-Group Elements

12

product of the simplest synthetic route (direct reaction of the elements at
increased pressure and temperature in a rotating autoclave) is a sintered substance
of low reactivity, contaminated with Na, and being of stoicheiometry NaH,.,.69 In

the presence of catalysts (e.g. R,CHCHO, R,CHCR,OH, R,CHCHROH, and
K,CHCO,H), however, a product of stoicheiometry NaH and of large specific
area is ~btained.~*
The kinetics of the uncatalysed reaction (conditions: 540 atm, 543-613 K) have been elucidated, and an apparent activation energy of
54.27 kJ mol-' has been determined.69

Oxides, Hydroxides, Sulphides, etc-The chemistry of rubidium and caesium
suboxides has been studied by Simon and c o - w ~ r k e r s . ~The
~ - ~preparation
~
and
crystal growth of Rb6O;l Rbg02,71cs70,72and C S , O ~has
~ been described. The
exact formula, [Rb902]Rb3, and structure of Rb60 have been derived from
single-crystal data, the crystals being grown at temperatures below 265 K in a
Weissenberg camera.71The characteristic [Rb902] units (Figure 3a), in which the
oxygen atoms are octahedrally co-ordinated, occur as in Rb902itself, alternating
with layers of metallic Rb. Similar structural chemistry is observed in the caesium
suboxides, in which the [Csl1O3] unit (Figure 3b) is a recurrent moiety; thus,
243 K, C S ~ Osingle-crystal
~~)
X-ray diffraclow-temperature (103,253 K,
tion studies show that the structures of C s 7 0 and @s,O correspond to the
formulae [CsllO,]Csl, and [Cs,,O,]Cs, respectively. In Cs,O, the [Csl103]clusters, in which the oxygens are again octahedrally co-ordinated (Figure 3b), form a

n

Oxygen

0

Rubidium, Caesium

Figure 3 Schematic representations of (a) the Rb,O, moiety in Rb,O, and (b) the Cs,,O,
moiety in Cs,O
[Reproduced by permission from (a) Reu. Chim. minerale, 1976, 13, 98, and (b) 2. anorg.
Chem., 1976, 423, 2031
71

72

73
74

A. Simon and H.-J. Deiseroth, Rev. Chim. minerale, 1976, 13, 98.
A. Simon, Z. anorg. Chem., 1976, 422, 208.
A. Simon, H.4. Deiseroth, E. Westerbeck, and B. Hillenkotter, 2. anorg. Chem., 1976, 423, 203.
G. Ebbinghaus, W. Braun, and A. Simon, 2. Naturforsch., 1976, 31b, 1219.


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Elements of Group I

13

hcp arrangement, the single Cs atoms occupying the quasi-octahedral sites of this
arrangement, as in the case of NiAs7,
UPS [He (I)] data for the suboxides Cs1103, [ C S ~ ~ O ~ ] and
C S ~[Cs1103]Rb7
~,

have been determined at 98*5 K.74 Extremely narrow oxygen 2p levels are
observed (Table 4) as well as significant differences in the binding energies of the
5p levels of chemically different Cs atoms. The results are rationalized in terms of
the structurally derived bonding models discussed above.74
Table 4 Binding energieslev in alkali-metal s ~ b o x i d e s ~ ~
Binding energies
O(2p) Rb(4p312) Rb(4p112) Cs(5p312) C ~ ( 5 p l ’ ~ )
Rb
15.2
16.1
cs
12.1
14.0
13.2
[c~iio~1c~io2.7
14.0
2.7
15.3
16.2
11.5
13.1
[CsiiO,]Rb
cs1103
2.7
11.6
13.3
Compound

{::::

The standard enthalpy of formation of Li,O, AHf)(Li,O,c,298.15 K) has been
calculated to be (-597.9 f 0.3) kJ mol-’ in a determination of the enthalpy of
reaction of Li,O with H,0.7s
An abortive attempted synthesis of Li(0,) [and of Ca(O,),], involving the
oxidation of LiOH [Ca(OH)2] in a low-pressure discharge, sustained in oxygen,
has been reported;76 the sole products of the reaction were Li,O, (CaO,).
A d.t.a.
of the melting temperatures of K,O (1013 K), KO, (778 K),
and K202 (818K), as well as the crystalline transition (dimorphous /3tetragonale P-NaC1 type cubic) temperature of KO2 (425 K), has been undertaken, using fritted CaO crucibles. The crystal symmetries of the two KO,
modifications, of K 2 0 (cubic anti-CaF,), and of K202 (orthorhombic) were
confirmed by X-ray diffraction techniques.77The melting temperature of KO2 has
also been determined in a study of the KO2-KNO, phase diagram.78 The
experimentally determined value for commercial KO, (773f 1K) was corrected
for assumed KOH impurities (xKOH=0.045)to give an a posteriori value of
(784f2) K. The KO,-KNO, phase diagram is a simple eutectic system, with
eutectic temperature and composition 495 f 1K and 34 mol % KO,, respectively.
Spectroscopic studies of Li(OH),H,O (i.r.),79Li(OD),D,O (i.r.?’ ,H n.m.r.80),
and M(OH),nH,O (M = Rb or Cs; n = or 1) (i.r.)79have been effected. Interpretation of the i.r. data for Li(OH),H,O is said to confirm the presence of
co-ordinated H 2 0 and OH- ion. The H,O and OH- ions in Li(OH),H20 form
discrete, planar, hydrogen-bonded [(OH-),(H,O),] anionic units, rather than the
extended chains observed in other alkali-metal hydroxide hydrates. The ,H n.m.r.
study (82K) of Li(OD),D,O has shown that the crystal is ordered. The ODpoints along the c-axis of the crystal and the plane of the D 2 0 molecule is
G. K. Johnson, R. T. Grow, and W. N. Hubbard, J. Chem. Thermodynamics, 1975, 7 , 781.
P. Sadhukan and A. T. Bell, J. Inorg. Nuclear Chem., 1976, 38, 1570.
77 A. deKozak, J.-C. Bardin, and A. Erb., Reu. Chim. minerale, 1976, 13, 190.
78 J. M. deJong and G. H.J. Broers, J. Chem. Thermodynamics, 1976, 8, 367.
79 I. Gennick and K. M. Harmon, Inorg. Chem., 1975, 14, 2214.
J. 0. Clifford, J. A. S. Smith, and F. P. Temme, J. C. S. Faraday II, 1975, 71, 1352.

75.

76