The chemistry of organic germanium, tin and lead compounds vol 1 1995 patai

The Chemistry of Organic Germanium, Tin and Lead Compounds. Volume 1
Edited by Saul Patai
Copyright  1995 John Wiley & Sons, Ltd.
ISBN: 0-471-94207-3

The chemistry of
organic germanium, tin
and lead compounds


THE CHEMISTRY OF FUNCTIONAL GROUPS
A series of advanced treatises under the general editorship of
Professors Saul Patai and Zvi Rappoport
The chemistry of alkenes (2 volumes)
The chemistry of the carbonyl group (2 volumes)
The chemistry of the ether linkage
The chemistry of the amino group
The chemistry of the nitro and nitroso groups (2 parts)
The chemistry of carboxylic acids and esters
The chemistry of the carbon nitrogen double bond
The chemistry of amides
The chemistry of the cyano group
The chemistry of the hydroxyl group (2 parts)
The chemistry of the azido group
The chemistry of acyl halides
The chemistry of the carbon halogen bond (2 parts)
The chemistry of the quinonoid compounds (2 volumes, 4 parts)
The chemistry of the thiol group (2 parts)
The chemistry of the hydrazo, azo and azoxy groups (2 parts)
The chemistry of amidines and imidates (2 volumes)
The chemistry of cyanates and their thio derivatives (2 parts)

The chemistry of diazonium and diazo groups (2 parts)
The chemistry of the carbon carbon triple bond (2 parts)
The chemistry of ketenes, allenes and related compounds (2 parts)
The chemistry of the sulphonium group (2 parts)
Supplement A: The chemistry of double-bonded functional groups (2 volumes, 4 parts)
Supplement B: The chemistry of acid derivatives (2 volumes, 4 parts)
Supplement C: The chemistry of triple-bonded functional groups (2 volumes, 3 parts)
Supplement D: The chemistry of halides, pseudo-halides and azides (2 volumes, 4 parts)
Supplement E: The chemistry of ethers, crown ethers, hydroxyl groups and their sulphur analogues
(2 volumes, 3 parts)
Supplement F: The chemistry of amino, nitroso and nitro compounds and their derivatives (2 parts)
The chemistry of the metal carbon bond (5 volumes)
The chemistry of peroxides
The chemistry of organic selenium and tellurium compounds (2 volumes)
The chemistry of the cyclopropyl group (2 parts)
The chemistry of sulphones and sulphoxides
The chemistry of organic silicon compounds (2 parts)
The chemistry of enones (2 parts)
The chemistry of sulphinic acids, esters and their derivatives
The chemistry of sulphenic acids and their derivatives
The chemistry of enols
The chemistry of organophosphorus compounds (3 volumes)
The chemistry of sulphonic acids, esters and their derivatives
The chemistry of alkanes and cycloalkanes
Supplement S: The chemistry of sulphur-containing functional groups
The chemistry of organic arsenic, antimony and bismuth compounds
The chemistry of enamines (2 parts)
The chemistry of organic germanium, tin and lead compounds
UPDATES
The chemistry of ˛-haloketones, ˛-haloaldehydes and ˛-haloimines

Nitrones, nitronates and nitroxides
Crown ethers and analogs
Cyclopropane derived reactive intermediates
Synthesis of carboxylic acids, esters and their derivatives
The silicon heteroatom bond
Syntheses of lactones and lactams
The syntheses of sulphones, sulphoxides and cyclic sulphides
Patai’s 1992 guide to the chemistry of functional groups

C Ge, C Sn, C Pb

Saul Patai


The chemistry of
organic germanium, tin
and lead compounds

Edited by
SAUL PATAI
The Hebrew University, Jerusalem

1995
JOHN WILEY & SONS
CHICHESTER NEW YORK BRISBANE TORONTO SINGAPORE

An Interscience R Publication


Copyright  1995 by John Wiley & Sons Ltd,

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Telephone: National
01243 779777
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No part of this book may be reproduced by any means,
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Library of Congress Cataloging-in-Publication Data
The chemistry of organic germanium, tin, and lead compounds / edited
by Saul Patai.
p.
cm. (The chemistry of functional groups)
‘An Interscience publication.’
Includes bibliographical references (p.
) and index.
ISBN 0-471-94207-3 (alk. paper)
1. Organogermanium compounds. 2. Organotin compounds.
3. Organolead compounds. I. Patai, Saul. II. Series.

QD412.G5C47 1995
547.050 684 dc20
95-19750
CIP
British Library Cataloguing in Publication Data
A catalogue record for this book is available from the British Library
ISBN 0 471 94207 3
Typeset in 9/10pt Times by Laser Words, Madras, India
Printed and bound in Great Britain by Biddles Ltd, Guildford, Surrey
This book is printed on acid-free paper responsibly manufactured from sustainable forestation, for
which at least two trees are planted for each one used for paper production.


Contributing authors
Harold Basch
Carla Cauletti
Marvin Charton

Peter J. Craig

J. T. van Elteren

Marcel Gielen
Charles M. Gordon
Sarina Grinberg
Tova Hoz
L. M. Ignatovich
Jim Iley

Jill A. Jablonowski

Helen Joly
¨
Thomas M. Klapotke

Joel F. Liebman

Department of Chemistry, Bar-Ilan University, RamatGan 52900, Israel
Dipartimento di Chimica, Universit`a di Roma ‘La
Sapienza’, Piazzale Aldo Moro 5, 00185 Roma, Italy
Chemistry Department, School of Liberal Arts and
Sciences, Pratt Institute, Brooklyn, New York 11205,
USA
Department of Chemistry, School of Applied Sciences,
De Montfort University, The Gateway, Leicester,
LE1 9BH, UK
Department of Chemistry, School of Applied Sciences,
De Montfort University, The Gateway, Leicester, LE1
9BH, UK
Faculty of Applied Sciences, Free University of Brussels,
Room 8G512, Pleinlaan 2, B-1050 Brussels, Belgium
School of Chemical Sciences, Dublin City University,
Dublin 9, Ireland
Institutes for Applied Research, Ben-Gurion University
of the Negev, Beer-Sheva 84110, Israel
Department of Chemistry, Bar-Ilan University, RamatGan 52900, Israel
Latvian Institute of Organic Synthesis, Riga, LV 1006
Latvia
Physical Organic Chemistry Research Group, Chemistry
Department, The Open University, Milton Keynes,

MK7 6AA, UK
Department of Chemistry and Biochemistry, University
of South Carolina, Columbia, South Carolina 29208,
USA
Department of Chemistry, Laurentian University, Sudbury, Ontario P3E 2C6, Canada
Institut f¨ur Anorganische und Analytische Chemie,
Technische Universit¨at Berlin, Strasse des 17 Juni 135,
D-10623 Berlin, Germany
Department of Chemistry and Biochemistry, University
of Maryland, Baltimore County, 5401 Wilkens Avenue,
Baltimore, Maryland 21228-5398, USA
v


vi
Conor Long
E. Lukevics
Kenneth M. Mackay
Shigeru Maeda

James A. Marshall

Michael Michman
Axel Schulz

Larry R. Sherman
˜
Jose´ A. Martinho Simoes
Suzanne W. Slayden

Stefano Stranges
John M. Tsangaris
Kenneth C. Westaway
Rudolph Willem
Jacob Zabicky

Contributing authors
School of Chemical Sciences, Dublin City University,
Dublin 9, Ireland
Latvian Institute of Organic Synthesis, Riga, LV 1006
Latvia
School of Science and Technology, University of Waikato,
P.B. 3105, Hamilton, New Zealand
Department of Applied Chemistry and Chemical Engineering, Faculty of Engineering, Kagoshima University,
1-21-40 Korimoto, Kagoshima 890, Japan
Department of Chemistry and Biochemistry, University
of South Carolina, Columbia, South Carolina 29208,
USA
Department of Organic Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
Institut f¨ur Anorganische und Analytische Chemie,
Technische Universit¨at Berlin, Strasse des 17 Juni 135,
D-10623 Berlin, Germany
Department of Chemistry, University of Scranton, Scranton, Pennsylvania 18519-4626, USA
Departamento de Qu´ımica, Faculdade de Ciˆencias,
Universidade de Lisboa, 1700 Lisboa, Portugal
Department of Chemistry, George Mason University,
4400 University Drive, Fairfax, Virginia 22030-4444,
USA
Dipartimento di Chimica, Universit`a di Roma ‘La
Sapienza’, Piazzale Aldo Moro 5, 00185 Roma, Italy

Department of Chemistry, University of Ioannina,
GR-45100 Ioannina, Greece
Department of Chemistry, Laurentian University, Sudbury, Ontario P3E 2C6, Canada
Faculty of Applied Sciences, Free University of Brussels,
Room 8G512, Pleinlaan 2, B-1050 Brussels, Belgium
Institutes for Applied Research, Ben-Gurion University
of the Negev, Beer-Sheva 84110, Israel


Foreword
As was the case with the volume The chemistry of organic arsenic, antimony and bismuth compounds, published in 1994, it was clear that the set of five volumes describing
organometallic compounds (edited by Professor Frank R. Hartley) did not deal in sufficient depth with organic compounds of germanium, tin and lead. Hence we decided to
publish the present volume, which we hope will be a useful and worthwhile addition
to the series The Chemistry of Functional Groups. In this volume the authors’ literature
search extended in most cases up to the end of 1994.
The following chapters unfortunately did not materialize: Mass spectra; NMR and
M¨ossbauer spectroscopy; Organic Ge, Sn and Pb compounds as synthones; Ge, Sn and
Pb analogs of radicals and of carbenes; and Rearrangements. Moreover, the volume does
not contain a ‘classical’ chapter on biochemistry, although much of the relevant material is
included in the chapter on environmental methylation of Ge, Sn and Pb and in the chapter
on the toxicity of organogermanium compounds, in the chapter on organotin toxicology
and also in the chapter on safety and environmental effects.
I hope that the above shortcomings will be amended in one of the forthcoming supplementary volumes of the series.
I will be indebted to readers who will bring to my attention mistakes or omissions in
this or in any other volume of the series.

SAUL PATAI

Jerusalem
May 1995

vii


The Chemistry of Functional Groups
Preface to the series
The series ‘The Chemistry of Functional Groups’ was originally planned to cover in
each volume all aspects of the chemistry of one of the important functional groups in
organic chemistry. The emphasis is laid on the preparation, properties and reactions of the
functional group treated and on the effects which it exerts both in the immediate vicinity
of the group in question and in the whole molecule.
A voluntary restriction on the treatment of the various functional groups in these
volumes is that material included in easily and generally available secondary or tertiary sources, such as Chemical Reviews. Quarterly Reviews, Organic Reactions, various
‘Advances’ and ‘Progress’ series and in textbooks (i.e. in books which are usually found
in the chemical libraries of most universities and research institutes), should not, as a rule,
be repeated in detail, unless it is necessary for the balanced treatment of the topic. Therefore each of the authors is asked not to give an encyclopaedic coverage of his subject,
but to concentrate on the most important recent developments and mainly on material that
has not been adequately covered by reviews or other secondary sources by the time of
writing of the chapter, and to address himself to a reader who is assumed to be at a fairly
advanced postgraduate level.
It is realized that no plan can be devised for a volume that would give a complete coverage of the field with no overlap between chapters, while at the same time preserving the
readability of the text. The Editors set themselves the goal of attaining reasonable coverage
with moderate overlap, with a minimum of cross-references between the chapters. In this
manner, sufficient freedom is given to the authors to produce readable quasi-monographic
chapters.
The general plan of each volume includes the following main sections:
(a) An introductory chapter deals with the general and theoretical aspects of the group.
(b) Chapters discuss the characterization and characteristics of the functional groups,
i.e. qualitative and quantitative methods of determination including chemical and physical
methods, MS, UV, IR, NMR, ESR and PES as well as activating and directive effects

exerted by the group, and its basicity, acidity and complex-forming ability.
(c) One or more chapters deal with the formation of the functional group in question,
either from other groups already present in the molecule or by introducing the new group
directly or indirectly. This is usually followed by a description of the synthetic uses of
the group, including its reactions, transformations and rearrangements.
(d) Additional chapters deal with special topics such as electrochemistry, photochemistry, radiation chemistry, thermochemistry, syntheses and uses of isotopically labelled
compounds, as well as with biochemistry, pharmacology and toxicology. Whenever applicable, unique chapters relevant only to single functional groups are also included (e.g.
‘Polyethers’, ‘Tetraaminoethylenes’ or ‘Siloxanes’).
ix


x

Preface to the series

This plan entails that the breadth, depth and thought-provoking nature of each chapter
will differ with the views and inclinations of the authors and the presentation will necessarily be somewhat uneven. Moreover, a serious problem is caused by authors who deliver
their manuscript late or not at all. In order to overcome this problem at least to some
extent, some volumes may be published without giving consideration to the originally
planned logical order of the chapters.
Since the beginning of the Series in 1964, two main developments have occurred.
The first of these is the publication of supplementary volumes which contain material
relating to several kindred functional groups (Supplements A, B, C, D, E, F and S). The
second ramification is the publication of a series of ‘Updates’, which contain in each
volume selected and related chapters, reprinted in the original form in which they were
published, together with an extensive updating of the subjects, if possible, by the authors
of the original chapters. A complete list of all above mentioned volumes published to
date will be found on the page opposite the inner title page of this book. Unfortunately,
the publication of the ‘Updates’ has been discontinued for economic reasons.
Advice or criticism regarding the plan and execution of this series will be welcomed

by the Editors.
The publication of this series would never have been started, let alone continued,
without the support of many persons in Israel and overseas, including colleagues, friends
and family. The efficient and patient co-operation of staff-members of the publisher also
rendered us invaluable aid. Our sincere thanks are due to all of them.
The Hebrew University
Jerusalem, Israel

SAUL PATAI
ZVI RAPPOPORT


Contents
1. The nature of the C M bond (M D Ge, Sn, Pb)
Harold Basch and Tova Hoz
2.

3.

4.

1

Structural aspects of compounds containing C E (E D Ge, Sn,
Pb) bonds
Kenneth M. Mackay

97

Stereochemistry and conformation of organogermanium, organotin

and organolead compounds
James A. Marshall and Jill A. Jablonowski

195

Thermochemistry of organometallic compounds of germanium, tin
and lead
Jos´e A. Martinho Sim˜oes, Joel F. Liebman and Suzanne
W. Slayden

5. ESR of organogermanium, organotin and organolead radicals
Jim Iley
6. Photoelectron spectroscopy (PES) of organometallic compounds
with C M (M D Ge, Sn, Pb) bonds
Carla Cauletti and Stefano Stranges

245

267

291

7. Analytical aspects of organogermanium compounds
Jacob Zabicky and Sarina Grinberg

339

8.

Analytical aspects of organotin compounds

Jacob Zabicky and Sarina Grinberg

365

9.

Analytical aspects of organolead compounds
Jacob Zabicky and Sarina Grinberg

429

10. Synthesis of M(IV) organometallic compounds where M D Ge,
Sn, Pb
John M. Tsangaris, Rudolph Willem and Marcel Gielen

453

11. Acidity, complexing, basicity and H-bonding of organic germanium,
tin and lead compounds: experimental and computational results
Axel Schulz and Thomas A. Klap¨otke

537

xi


xii

Contents

12.

Substituent effects of germanium, tin and lead groups
Marvin Charton

13.

The electrochemistry of alkyl compounds of germanium, tin
and lead
Michael Michman

665

The photochemistry of organometallic compounds of germanium,
tin and lead
Charles M. Gordon and Conor Long

723

Syntheses and uses of isotopically labelled organic derivatives of
Ge, Sn and Pb
Kenneth C. Westaway and Helen Joly

759

14.

15.

603

16.

The environmental methylation of germanium, tin and lead
P. J. Craig and J. T. van Elteren

843

17.

Toxicity of organogermanium compounds
E. Lukevics and L. M. Ignatovich

857

18.

Organotin toxicology
Larry R. Sherman

865

19.

Safety and environmental effects
Shigeru Maeda

871

Author index

911

Subject index

975


List of abbreviations used
Ac
acac
Ad
AIBN
Alk
All
An
Ar

acetyl (MeCO)
acetylacetone
adamantyl
azoisobutyronitrile
alkyl
allyl
anisyl
aryl

Bz
Bu

benzoyl (C6 H5 CO)
butyl (also t-Bu or But )

CD
CI
CIDNP
CNDO
Cp
CpŁ

circular dichroism
chemical ionization
chemically induced dynamic nuclear polarization
complete neglect of differential overlap
Á5 -cyclopentadienyl
Á5 -pentamethylcyclopentadienyl

DABCO
DBN
DBU
DIBAH
DME
DMF
DMSO

1,4-diazabicyclo[2.2.2]octane
1,5-diazabicyclo[4.3.0]non-5-ene
1,8-diazabicyclo[5.4.0]undec-7-ene
diisobutylaluminium hydride
1,2-dimethoxyethane

N , N -dimethylformamide
dimethyl sulphoxide

ee
EI
ESCA
ESR
Et
eV

enantiomeric excess
electron impact
electron spectroscopy for chemical analysis
electron spin resonance
ethyl
electron volt

xiii


xiv

List of abbreviations used

Fc
FD
FI
FT
Fu

ferrocenyl
field desorption
field ionization
Fourier transform
furyl(OC4 H3 )

GLC

gas liquid chromatography

Hex
c-Hex
HMPA
HOMO
HPLC

hexyl(C6 H13 )
cyclohexyl(C6 H11 )
hexamethylphosphortriamide
highest occupied molecular orbital
high performance liquid chromatography

iIp
IR
ICR

iso
ionization potential
infrared
ion cyclotron resonance

LAH
LCAO
LDA
LUMO

lithium aluminium hydride
linear combination of atomic orbitals
lithium diisopropylamide
lowest unoccupied molecular orbital

M
M
MCPBA
Me
MNDO
MS

metal
parent molecule
m-chloroperbenzoic acid
methyl
modified neglect of diatomic overlap
mass spectrum

n
Naph
NBS
NCS
NMR

normal
naphthyl
N -bromosuccinimide
N -chlorosuccinimide
nuclear magnetic resonance

Pc
Pen
Pip
Ph
ppm
Pr
PTC
Pyr

phthalocyanine
pentyl(C5 H11 )
piperidyl(C5 H10 N)
phenyl
parts per million
propyl (also i -Pr or Pri )
phase transfer catalysis or phase transfer conditions
pyridyl (C5 H4 N)


List of abbreviations used
R
RT

any radical
room temperature

sSET
SOMO

secondary
single electron transfer
singly occupied molecular orbital

tTCNE
TFA
THF
Thi
TLC
TMEDA
TMS
Tol
Tos or Ts
Trityl

tertiary
tetracyanoethylene
trifluoroacetic acid
tetrahydrofuran
thienyl(SC4 H3 )
thin layer chromatography
tetramethylethylene diamine
trimethylsilyl or tetramethylsilane
tolyl(MeC6 H4 )

tosyl(p-toluenesulphonyl)
triphenylmethyl(Ph3 C)

Xyl

xylyl(Me2 C6 H3 )

xv

In addition, entries in the ‘List of Radical Names’ in IUPAC Nomenclature of Organic
Chemistry, 1979 Edition. Pergamon Press, Oxford, 1979, p. 305 322, will also be used
in their unabbreviated forms, both in the text and in formulae instead of explicitly drawn
structures.


The Chemistry of Organic Germanium, Tin and Lead Compounds. Volume 1
Edited by Saul Patai
Copyright  1995 John Wiley & Sons, Ltd.
ISBN: 0-471-94207-3

CHAPTER

1

The nature of the C M bond
(M = Ge, Sn, Pb)
HAROLD BASCH and TOVA HOZ
Department of Chemistry, Bar-Ilan University, Ramat-Gan 52900, Israel
Fax: +(972)-3-535-1250; e-mail:

I.
II.
III.
IV.

INTRODUCTION . . . . . . . . . . . .
ATOMIC PROPERTIES . . . . . . . .
CALCULATIONAL METHODS . . .
STRUCTURES . . . . . . . . . . . . . .
A. XH4 . . . . . . . . . . . . . . . . . . .
B. XH3 A . . . . . . . . . . . . . . . . . .
C. XH3 AH . . . . . . . . . . . . . . . . .
D. XH3 AH2 . . . . . . . . . . . . . . . .
E. XH3 AH3 . . . . . . . . . . . . . . . .
F. XH3 AB . . . . . . . . . . . . . . . . .
G. XH3 ABH . . . . . . . . . . . . . . .
H. XH3 ABH3 . . . . . . . . . . . . . . .
I. XH3 ABH5 . . . . . . . . . . . . . . .
J. XH3 ABC . . . . . . . . . . . . . . . .
K. XH3 ABCH . . . . . . . . . . . . . .
L. XH3 ABCH2 . . . . . . . . . . . . . .
M. XH3 ABCH3 . . . . . . . . . . . . . .
N. XH3 ABCD . . . . . . . . . . . . . .
O. XH3 ABCDH . . . . . . . . . . . . .
P. XH3 ABCDH3 . . . . . . . . . . . .
V. BOND DISSOCIATION ENERGIES
A. XH4 . . . . . . . . . . . . . . . . . . .
B. XH3 A . . . . . . . . . . . . . . . . . .
C. XH3 AH . . . . . . . . . . . . . . . . .
D. XH3 AH2 . . . . . . . . . . . . . . . .

E. XH3 AH3 . . . . . . . . . . . . . . . .
F. XH3 AB . . . . . . . . . . . . . . . . .
G. XH3 ABH . . . . . . . . . . . . . . .
H. XH3 ABH3 . . . . . . . . . . . . . . .
I. XH3 ABH5 . . . . . . . . . . . . . . .

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2
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5
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71
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73
75
78
79
81
85
85
86
86
86
87

88
88
89


2
J. XH3 ABC . . .
K. XH3 ABCH .
L. XH3 ABCH2 .
M. XH3 ABCH3 .
N. XH3 ABCD .
O. XH3 ABCDH3
VI. REFERENCES .

Harold Basch and Tova Hoz
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89
89
90
90
90
90
91

I. INTRODUCTION
The nature of the carbon M bond as a function of the metal (M) atoms Ge, Sn and Pb
has been traditionally described using differences in the atomic properties of these atoms
to explain trends in molecular bonding characteristics such as bond distances, angles and
energy properties. Emphasis has been on a comparison of properties contrasting behavior

relative to carbon and silicon bonding to C, and among the metals themselves. The
importance of relativistic effects in determining the properties of the heavier metal ligand
bonds has also been extensively addressed.
The ability of the lightest of the Group 14 atoms, the carbon atom, to bind in so many
ways with carbon and with other atoms in the Periodic Table attracts extensive comparison
with the analogous compounds of Si, Ge, Sn and Pb, both real and hypothetical. The wider
the comparison, the greater the opportunity to gain insight into the secrets of chemical
binding involving the Group 14 atoms, and to detect the nuances that differentiate their
properties. Some of the causes of the differences are large, obvious and consistent. Other
causes are more subtle and difficult to identify. A combination of contrary trends can
effectively mask their individual characters when the individual effects are small.
The most obvious property to examine for trends and their causes is geometric structure. Historically, bond lengths and bond angles in molecules were used to elucidate
electronic structure trends and construct descriptions of chemical bonding1 . The major
obstacle hindering this approach is the general lack of a sufficiently large number and
variety of experimentally known molecular structures. Happily, recent developments in
ab initio electronic structure theory have provided chemists with the tools for accurately
calculating geometric structures for ever-increasing sizes of molecules2 . At the same time,
developments in relativistic effective core potentials (RCEP)3 have allowed the incorporation of both direct and indirect radial scaling effects due to relativistic properties of the
core electrons in the heavier atoms into the electronic structure description of their valence
electrons. As has been known for some time already, certain differences in chemical properties in going down a column in the Periodic Table can be attributed to relativistic effects
in the heavier atoms4 .
Therefore, the common approach to building a bonding description of these type compounds is to combine the few experimentally known geometric structures with a larger
number of theoretically calculated geometries to infer bonding properties and trends in
simple Group 14 compounds. It is, however, first necessary to identify those atomic
properties which distinguish the various Group 14 atoms and which can contribute to
differences in the properties of their corresponding compounds. Of course, the same
properties which can be used to explain trends in geometric structure could also be used
for energy properties, such as bond dissociation energies. However, energy properties
typically involve both an initial state and a final state, where the energetics of the process
depend on the difference in properties between the two states, both involving the same

Group 14 atom. Trends in energy properties as a function of atom then involve another
differencing step. This can be more subtle and difficult than treating just geometry, which
involves only one state. In addition, theoretical methods for calculating geometry are more
developed and reliable than for energy difference properties.


1. The nature of the C M bond (M D Ge, Sn, Pb)

3

In this review we will first discuss the atomic properties that are expected to be relevant to trends in molecular structure and bonding for compounds of the Group 14 atoms5 .
Reference will be made mainly to atomic radii6 and atomic orbital energies6 9 . The resultant conclusions will contribute to interpreting trends in the geometric structures of small
molecules having the generic formula XH3 Y, where X D C, Si, Ge, Sn and Pb, and
Y is one of the 53 substituents ranging from Y D H to Y D C(O)OCH3 . The calculated XH3 Y bond energies will also be presented and analyzed. The generated data will
allow other derivative thermodynamic quantities for simple generic-type chemical reactions involving the Group 14 atom compounds to be calculated. The XH3 Y molecules
are restricted to those having a formal single bond between the Group 14 atom X and the
direct bonding atom of the Y group.
II. ATOMIC PROPERTIES

The atomic properties of most relevance to determining the structure and energies of
molecular compounds have been identified and discussed4,5 . The values of these properties
are collected in Table 16 16 . The ground-state electronic configuration of the Group 14
atoms is [core]ns2 np2 , with n D 2,3,4,5 and 6 for C, Si Ge, Sn and Pb, respectively.
In L S coupling the electronic ground state has the term symbol 3 P . Relativistic effects
are very large for the heaviest atom, lead, with a spin orbit coupling in the thousands
17
of cm 1 . The splitting of the valence np1/2 and np3/2 spinors can affect molecular
binding through their different spatial and energetic interactions with other atoms, even in
closed-shell electronic states18 . For simplicity, spin orbit averaged values for calculated
properties are shown in Table 1 for discussing trends and making comparisons.

The trend in orbital energy values for the valence ns and np atomic orbitals going
down the Group 14 column is shown in Table 1. The orbital energies are taken from the
numerical atomic Dirac Fock compilation of Desclaux6 and these open-shell systems
do not rigorously obey Koopmans’ Theorem19 . As such, besides the other approximations
inherent to Koopmans’ Theorem, these orbital energies can only give a rough measure of
values and trends in the atomic orbital ionization energies. In any event, these numbers
show an interesting behavior which must reflect fundamental underlying effects. The
(absolute value) np orbital energy is seen to decrease steadily, if not uniformly, with
increasing atom size. There is a relatively very large energy gap between the carbon and
silicon atoms, small gaps among the Si Ge and Sn Pb pairs, and a somewhat larger
energy gap between the Ge and Sn orbital energies. The valence ns atomic orbital energy,
on the other hand, is seen to have a sawtooth, alternating behavior in going down the
Group 14 column20 . As with the np atomic orbital, there is a very large energy decrease
between carbon and silicon, but from Si the orbital energies alternately increase and
decrease. Again, the differences between Si and Ge and between Sn and Pb are small,
while the gap between Ge and Sn is larger.
The experimental ionization energies7 9 in Table 1 show similar trends; ns ionization
alternates, while np ionization decreases until Pb, where it increases slightly. Again, there
is a large energy gap between carbon and silicon. The calculated atomic radii (hri) for
the Desclaux orbitals6 in Table 1 mirror the general behavior of the orbital and ionization
energies: sawtooth for ns and uniformly increasing for np, where the np values for Sn
and Pb are almost equal.
Although it is not completely clear which definition of each property is most appropriate for discussing molecular bonding (i.e. with or without spin orbit averaging, radial
maxima or expectation values, choice of final state for ionization energy, etc.) the general trends seem to be roughly independent of definition. The size and energies of the
two valence atomic orbitals, which properties should be very important for the atom’s


4

Harold Basch and Tova Hoz

TABLE 1.

Properties of the Group 14 atoms

Atom
n
Orbital energya
ns
npb
Ionization energyc
nsb,d
npb,e
Electron affinityf
Polarizabilityg
Electronegativityh
Mullikeni
Paulingj
Allenk
Atomic radiusl
ns
npb

C
2

Si
3

Ge
4

Sn
5

Pb
6

19.39
11.07

14.84
7.57

15.52
7.29

13.88
6.71

15.41
6.48

16.60
11.26
1.26
1.76

13.64
8.15
1.39

5.38

14.43
7.90
1.23
6.07

13.49
7.39
1.11
7.7

16.04
7.53
0.36
6.8

1.92
2.55
2.28

1.46
1.90
1.76

1.40
2.01
1.81

1.30

1.96
1.68

1.21
2.33
1.91

1.58
1.74

2.20
2.79

2.19
2.88

2.48
3.22

2.39
3.22

a In eV; from Reference 6.
b Spin-orbit averaged.
c In eV; from References 7 9.
d For the process, ns2 np2 (3 P ) ! ns1 np2 (4 P ).
e For the process, ns2 np2 (3 P ) ! ns2 np1 (2 P ).
f In eV; from References 10 and 11.
g In 10 24 cm3 ; from References 12 and 13; dipole polarizability.
h Relative to hydrogen D 2.20.

i Average of np atomic ionization energy and electron affinity. Data from appropriate lines in this Table. See

Reference 14.

j Pauling scale (Reference 1) as calculated in Reference 15.
k Weighted average of ns and np ionization energies from the appropriate lines in this Table. See Reference 16.
l hri in au; from Reference 6.

chemical behavior, generally show different trends for ns and np. The ns energy alternates with increasing atom size while the np energy generally decreases steadily, at least
until Pb. The result is a nonuniform trend in energy gap between the ns and np atomic
orbitals which can affect the degree of ns np hybridization in chemical bonds involving
the Group 14 atoms, and, thereby, the chemical behavior of their molecular compounds.
On the other hand, the ns np atomic radius (hri) difference increases steadily with atomic
number, with a particularly large change between carbon and silicon. This difference can
also affect the degree of ns np hybridization through the (radial) overlap which controls
the bonding effectiveness of resultant hybrid valence orbitals. We can therefore anticipate
a somewhat complex, somewhat alternating chemical behavior going down the Group 14
column of the Periodic Table1,4,16,20 .
Another property which anticipates these trends is the electronegativity, also shown for
several definitions in Table 1. Pauling’s empirical electronegativity scale based on bond
energies, as updated by Allerd15 , shows a sawtooth behavior, with predictable chemical consequences. Electronegativity is used to correlate a vast number of chemical and
physical properties. Allen’s revised definition of electronegativity16 as the average configuration energy of the valence ns and np electrons also shows the alternating behavior with
atomic number in the Group 14 column, as expected from the above discussion of orbital
and ionization energies. The Mulliken definition14 , based on just the np atomic orbital
ionization energy and the corresponding electron affinity, does not show the sawtooth


1. The nature of the C M bond (M D Ge, Sn, Pb)

5

behavior, and must be considered deficient for neglecting the effect of the ns atomic
orbital on chemical behavior. The Mulliken scale also defines a higher electronegativity
for hydrogen relative to carbon15 .
The source of the differential behavior between the ns and np atomic orbitals in going
down the Group 14 column of the Periodic Table can be attributed to a combination
of screening and relativistic effects, both of which preferentially stabilize the ns atomic
orbital4,16 . Filling the first transition series affects germanium this way through incomplete
screening of its 4s atomic orbital which gives it a higher effective nuclear charge. Filling
the first lanthanide series analogously stabilizes the Pb 6s atomic orbital through incomplete screening, which is further enhanced by relativistic effects4,20 . Although incomplete
screening and relativistic terms also affect the np atomic orbital, the stabilization is
stronger for the ns atomic orbital because of its nonzero charge density at the nucleus.
The dipole polarizability term for the atoms (in Table 1) shows the usual gap between
carbon and silicon, increasing values for Si ! Sn and a decrease at lead. This is another
reason to expect somewhat unusual behavior for lead compounds compared to the lighter
metals.
The role of d-type orbitals is not addressed in Table 1. This subject has been addressed
for second-row atoms in previous reviews21,22 which contain many references to this
subject. It is very difficult to define the energy and radius of the outer-sphere d-type
orbitals (nd) in isolated atoms since they are not occupied in the ground state. Rather
than make use of some excited state definition, we prefer to postpone a discussion of this
subject until after an inspection of the calculated results on the molecular compounds.
III. CALCULATIONAL METHODS

Using atomic properties alone for predictive capabilities with regard to the geometric and
electronic structure of molecules is often insufficient. Except for weakly bound systems,
the chemical bond is more than just a perturbation of the electronic structure of atoms.
Molecular properties determined experimentally have been used to infer the electronic
structure description of simple systems, from which predictions are made for more complicated molecules using group property and additivity concepts. This empirical approach
has been used very extensively in identifying and defining the determining factors in the

geometric and electronic structure of molecules. These latter are then used in a predictive
mode for unknown systems. The opposite approach is to use ab initio quantum chemical
calculations to determine everything. The disadvantages in the latter methodology is that
no intuitive understanding is derived from the purely mechanical calculational process
which can be used for chemical systems that are too large for the ab initio machinery.
In this review we will try to combine the best of both approaches. On the one hand,
there are very little experimental data for the Group 14 compounds for the atoms below
Si. For simple molecular compounds of Ge, Sn and Pb, ab initio methods can be used
to generate an ‘experimental’ database from which the electronic structure properties of
such compounds can be inferred. Hopefully, the principles learned from this reference
set of molecules can then be applied to larger systems. Although not the subject of
this chapter, the corresponding carbon and silicon21 systems are also examined to help
elucidate trends in properties going down the complete Group 14 column of the Periodic
Table and for general comparison purposes. More experimental information is available for
the corresponding carbon and silicon compounds so that these can also be used to evaluate
the accuracy of the calculated properties of the germanium, tin and lead database set.
The ab initio methods and approach used here are similar to that reported in previous
studies22 24 . The geometries of a generic set of XH3 Y molecules were determined
calculationally. X is any one of the Group 14 atoms (carbon, silicon, germanium, tin
and lead) and Y is any of the substituent groups, F, AlH2 , BH2 , SH, Br, H, CÁCH, PH2 ,


6

Harold Basch and Tova Hoz

NH2 , SCH3 , Cl, NO, ON, C(O)H, SeCN, NCSe, C(O)F, C(O)NH2 , ONO2 , NCS, SCN,
CH2 CH3 , C(O)OH, NO2 , ONO, PC, CP, NCO, OCN, CN, NC, OCH3 , CHDCH2 , NNN,
OH, CH3 , SiH3 , GeH3 , SnH3 , PbH3 , CF3 , C(O)OCH3 , OC(O)CH3 , PO, OP, C(O)Cl,
OF, OSiH3 , C(O)CH3 , PO2 , OPO, OPO2 and OS(O)OH. The Y substituents are written

where attachment to X is through the leftmost atom. Attachment to X alternately by
different atoms of the Y group gives rise to the possibility of linkage isomerism for the
Y group. The plethora of bonding possibilities with respect to type of atom, attachment
site, substitution and conformation should combine to give a balanced and comprehensive
picture of the chemical bonding situation in these systems.
The geometries of the XH3 Y molecules were optimized at the MP2 (Moeller Plesset
to second order) level2 using compact effective potentials (CEP) for the atoms in the
first two rows of the Periodic Table (B F and Al Cl)25 and their relativistic analogs
(RCEP) for the main group atoms below the second row26 . The RCEP are generated from
Dirac Fock all-electron relativistic atomic orbitals6,27 and therefore implicitly include the
indirect relativistic effects of the core electrons on the radial distribution of the valence
electrons18 . This could be particularly important for the lead atom. The effective potentials
or pseudopotentials replace the chemically inactive core electrons.
The valence electron Gaussian basis sets were taken from the respective CEP25 and
RCEP26 tabulations. The published basis sets show a valence atomic orbital splitting
that can be denoted as (R)CEP-N1G, where N D 3 for first- and second-row atoms,
and N D 4 for the heavier main group elements. This type basis set is generically called
double-zeta (DZ) for historical reasons connected to Slater orbital (exponential-type) basis
sets. In these calculations the valence DZ distributions were converted to triple-zeta (TZ)
by splitting off the smallest exponent Gaussian member of the contracted (N ) set, to give
the (R)CEP-K 11 valence atomic orbital distribution (K D 2 for first- and second-row
atoms and K D 3 for beyond). The valence TZ Gaussian basis set for each atom was
augmented by a double (D) set of d-type polarization (DP) functions (all 6 components)
taken from the GAMESS tabulation28,29 as follows. The reported29 single Gaussian d-type
polarization function was converted to DP form by scaling the single Gaussian exponent
(˛) by 1.4˛ and 0.4˛ to form two distinct d-type polarization functions. Both the single
and double set of single Gaussians exponents are displayed in Table 2. The valence TZ
hydrogen atom basis set was taken from the GAUSSIAN9230 code as the 311G group, and
augmented by a single Gaussian p-type polarization function with exponent 0.9. Overall,
this basis set is denoted TZDP. All geometry optimizations were carried out in this basis

set at the MP2 level (denoted MP2/TZDP or MP2/CEP-TZDP) using the GAUSSIAN9230
set of computer programs.
The extended basis sets are necessary to describe the adaptation of the atom to the
molecular environment. Experience has shown31 that the major effect on the radial extent
of each atom in a molecule is in the bonding region. A frozen atomic orbital basis set is
unable to provide the differential flexibility required in the short, intermediate and longrange radial distances from the nucleus to accurately describe the electron density changes
in the molecule. The valence TZ basis set has that flexibility. Analogously, Magnusson32
has recently discussed the effect of angular polarization functions on the inner and outer
parts of the valence atomic orbitals of the main group elements The different polarization
needs in the different regions of space about each atom in the molecule leads to the use
of a double set of d-type basis function.
The MP2 level calculation is the first step beyond the Hartree Fock (HF) level33,34 ,
and is thereby defined as a post-Hartree Fock method. Theory predicts35 and actual calculations have shown2 that HF level calculated geometries generally give bond distances
that are too short compared to experiment for normal covalent bonds. For these cases,
MP2 level optimized geometries give better agreement with experiment36 . The same is


1. The nature of the C M bond (M D Ge, Sn, Pb)
TABLE 2. Polarization and diffuse Gaussian

7

exponentsa

Polarization
doubleb

single
Atom
H

B
C
N
O
F
Al
Si
P
S
Cl
Ge
Se
Br
Sn
Pb

˛

˛1

˛2

Diffuse
single
Gaussian

0.9000
0.7000
0.7500
0.8000

0.8500
0.9000
0.3250
0.3950
0.4650
0.5420
0.6000
0.2460
0.3200
0.3600
0.1830
0.1640

0.9800
1.050
1.120
1.190
1.260
0.4550
0.5530
0.6510
0.7588
0.8400
0.3444
0.4480
0.5040
0.2562
0.2296

0.2800

0.3000
0.3200
0.3400
0.3600
0.1300
0.1580
0.1860
0.2168
0.2400
0.0984
0.1280
0.1440
0.0732
0.0656

0.03237
0.02559
0.03691
0.05171
0.06181
0.07461
0.01691
0.02324
0.02919
0.03461
0.04395
0.02132
0.02934
0.03574
0.01858

0.01574

a Except for H, the polarization functions are d-type and the diffuse functions

are sp-type. For the hydrogen atom polarization is p-type and diffuse is s-type.
b ˛ D 1.4˛; ˛ D 0.4˛; values of ˛ are from Ref. 29.
1
2

true for vibrational frequencies37 . The reason for the improved description of the normal
covalent bond at the post-HF level is the improved description of the incipient homolytic
bond dissociation process (i.e. reduced ionicity) at the MP2 level compared to HF in the
neighborhood of the equilibrium bond distances. The resultant geometry optimized bond
lengths are listed in Tables 3 8.
˚ not involving Group 14 atomsa
TABLE 3. Bond distances (in A)
Bond type
Compound
CH3 NO2
SiH3 NO2
GeH3 NO2
SnH3 NO2
PbH3 NO2
CH3 ONO
SiH3 ONO
GeH3 ONO
SnH3 ONO
PbH3 ONO
CH3 OH
SiH3 OH

GeH3 OH
SnH3 OH
PbH3 OH
CH3 NNN
SiH3 NNN

B Hb
Al Hb

N Hb
P Hb

O H
S H

ND N

NÁN

N O
P O

NDO
PDO

1.411
1.481
1.374
1.338
1.306

1.241b
1.252b
1.250b
1.251b
1.248b
1.203
1.180
1.216
1.231
1.245

0.967
0.965
0.968
0.968
0.971
1.246
1.233

1.159
1.168
(continued overleaf )


8

Harold Basch and Tova Hoz

TABLE 3. (continued )

Bond type
Compound

B Hb
Al Hb

N Hb
P Hb

O H
S H

GeH3 NNN
SnH3 NNN
PbH3 NNN
CH3 ONO2

ND N
1.237
1.234
1.242

NÁN

N O
P O

NDO
PDO

1.422

1.217
1.223b
1.214
1.232b
1.218
1.236b
1.220
1.247b
1.223
1.259b
1.233
1.252
1.240
1.238
1.224
1.251

1.169
1.173
1.175

SiH3 ONO2

1.405

GeH3 ONO2

1.388

SnH3 ONO2

1.366

PbH3 ONO2

1.345

CH3 NO
SiH3 NO
GeH3 NO
SnH3 NO
PbH3 NO
CH3 ON
SiH3 ONc
GeH3 ON
SnH3 ON
PbH3 ON
CH3 SH
SiH3 SH
GeH3 SH
SnH3 SH
PbH3 SH
CH3 C(O)OH
SiH3 C(O)OH
GeH3 C(O)OH
SnH3 C(O)OH
PbH3 C(O)OH
CH3 NH2

SiH3 NH2
GeH3 NH2
SnH3 NH2
PbH3 NH2
CH3 PH2
SiH3 PH2
GeH3 PH2
SnH3 PH2
PbH3 PH2
CH3 BH2
SiH3 BH2
GeH3 BH2
SnH3 BH2
PbH3 BH2
CH3 AlH2
SiH3 AlH2
GeH3 AlH2
SnH3 AlH2
PbH3 AlH2
CH3 C(O)NH2

1.277
1.285
1.257
1.320
1.322
1.322
1.322
1.321
0.976

0.980
0.980
0.981
0.981
1.019
1.014
1.018
1.019
1.023
1.412
1.413
1.413
1.414
1.413
1.193
1.190
1.189
1.189
1.186
1.584
1.582
1.581
1.582
1.579
1.011


1. The nature of the C M bond (M D Ge, Sn, Pb)

9

TABLE 3. (continued )
Bond type
Compound
SiH3 C(O)NH2
GeH3 C(O)NH2
SnH3 C(O)NH2
PbH3 C(O)NH2
CH3 PO
SiH3 PO
GeH3 PO
SnH3 PO
PbH3 PO
CH3 OP
SiH3 OP
GeH3 OP
SnH3 OP
PbH3 OP
CH3 PO2
SiH3 PO2
GeH3 PO2
SnH3 PO2
PbH3 PO2
CH3 OPO
SiH3 OPO
GeH3 OPO
SnH3 OPO
PbH3 OPO
CH3 OF
SiH3 OF

GeH3 OF
SnH3 OF
PbH3 OF
CH3 OS(O)OH
SiH3 OS(O)OH
GeH3 OS(O)OH
SnH3 OS(O)OH
PbH3 OS(O)OH
CH3 OPO2

B Hb
Al Hb

N Hb
P Hb

O H
S H

ND N

NÁN

N O
P O

NDO
PDO

1.012

1.012
1.013
1.013
1.513
1.527
1.524
1.524
1.520
1.621
1.640
1.631
1.631
1.624

1.627
1.627
1.615
1.602
1.582
1.455d
1.465d
1.464d
1.470d
1.473d
0.979
0.980
0.980
0.980
0.979

1.630e
1.633e
1.611e
1.590e
1.564e

1.483b
1.488b
1.489b
1.491b
1.491b
1.499
1.499
1.503
1.509
1.523

1.659f
1.641f
1.652f
1.649f
1.651f
1.592

SiH3 OPO2

1.586

GeH3 OPO2

1.580

SnH3 OPO2

1.572

PbH3 OPO2

1.563

a MP2 optimized geometries in the TZDP basis set.
b Averaged.
c Not calculated.
d O F.
e (X) O S.
f S O(H).
g SDO.
h Facing X.

1.464g
1.465g
1.470g
1.482g
1.500g
1.476
1.482h
1.475
1.484h
1.477
1.487h

1.478
1.492h
1.478
1.501h


10

Harold Basch and Tova Hoz

˚ involving carbona
TABLE 4. Bond distances (in A)
Bond type
C

Hb

C C

CDCc

C N
C P

CDNc
CDPc

Compound
CH3 OCH3
SiH3 OCH3

GeH3 OCH3
SnH3 OCH3
PbH3 OCH3
CH3 NO2
CH3 ONO
CH3 OH
CH3 Cl
CH3 CP
SiH3 CP
GeH3 CP
SnH3 CP
PbH3 CP
CH3 PC
SiH3 PC
GeH3 PC
SnH3 PC
PbH3 PC
CH3 CH3
SiH3 CH3
GeH3 CH3
SnH3 CH3
PbH3 CH3
CH4
CH3 CHCH2

SiH3 CHCH2
GeH3 CHCH2
SnH3 CHCH2
PbH3 CHCH2
CH3 NNN

CH3 CN
SiH3 CN
GeH3 CN
SnH3 CN
PbH3 CN
CH3 NC
SiH3 NC
GeH3 NC
SnH3 NC
PbH3 NC
CH3 SCN
SiH3 SCN

1.095
1.093
1.094
1.095
1.097
1.087
1.090
1.093
1.086
1.093

1.089

1.089

CDOc
CDSc

CDSec

C F
C Cl
C Br

1.423
1.434
1.433
1.430
1.432
1.496
1.446
1.433
1.796
1.471

1.090

1.092
1.092
1.091
1.091
1.088
1.089
1.093
1.088d
1.085e
1.089d
1.086e

1.088d
1.086e
1.089d
1.087e
1.086d
1.087e
1.090
1.090

C O
C S
C Se

1.859

1.571
1.577
1.577
1.578
1.578
1.639
1.636
1.635
1.633
1.633

1.533

1.503

1.339

1.346
1.343
1.345
1.341
1.487
1.466

1.432

1.174
1.178
1.178
1.179
1.180
1.185
1.189
1.189
1.190
1.190
1.181
1.181

1.812

1.684
1.685

C B

C Al


1. The nature of the C M bond (M D Ge, Sn, Pb)

11

TABLE 4. (continued )
Bond type
C Hb

C C

CDCc

C N
C P

C D Nc
CDPc

Compound
GeH3 SCN
SnH3 SCN
PbH3 SCN
CH3 NCS
SiH3 NCS
GeH3 NCS
SnH3 NCS
PbH3 NCS

CH3 OCN
SiH3 OCN
GeH3 OCN
SnH3 OCN
PbH3 OCN
CH3 NCO
SiH3 NCO
GeH3 NCO
SnH3 NCO
PbH3 NCO
CH3 SCH3
SiH3 SCH3
GeH3 SCH3
SnH3 SCH3
PbH3 SCH3
CH3 CH2 CH3
SiH3 CH2 CH3
GeH3 CH2 CH3
SnH3 CH2 CH3
PbH3 CH2 CH3
CH3 CF3
SiH3 CF3
GeH3 CF3
SnH3 CF3
PbH3 CF3
CH3 CCH
SiH3 CCH
GeH3 CCH
SnH3 CCH
PbH3 CCH

CH3 ONO2
CH3 F
CH3 NO
CH3 ON
CH3 C(O)H

1.091

1.444

1.089

1.090

1.091
1.090
1.090
1.089
1.090
1.093
1.095e
1.095e
1.093
1.095e
1.094
1.094
1.091e
1.094
1.089

1.092
1.063d
1.066
1.065
1.066
1.066
1.089
1.090
1.092
1.088
1.092

1.457

1.182
1.183
1.184
1.204
1.204
1.208
1.202
1.218
1.180
1.180
1.182
1.183
1.185
1.216
1.213
1.217

1.213
1.226

C O
C S
C Se

1.465

CDOc
CDSc
CDSec

C F
C Cl
C Br

C B
C Al

1.683
1.682
1.680
1.571
1.566
1.569
1.574
1.574
1.303
1.299

1.296
1.292
1.291
1.186
1.183
1.185
1.188
1.189

1.795
1.817
1.815
1.819
1.817
1.531
1.531
1.540
1.536
1.537
1.531
1.503

1.355
1.361
1.361
1.364
1.359

1.467
1.217

1.225
1.224
1.226
1.225
1.446
1.400
1.484
1.500
1.507

1.221
(continued overleaf )