Table Of ContentEnergetics of Organometallic Species
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Series C: Mathematical and Physical Sciences - Vol. 367
Energetics of
Organometallic Species
edited by
J. A. Martinho Simoes
Departmento de Engenharia Ouimica,
Instituto Superior Tecnico,
Usbon, Portugal
Springer Science+Business Media, B.V.
Proceedings of the NATO Advanced Study Institute on
Energetics of Organometallic Species
Curia, Portugal
September 3-13, 1991
Library of Congress cataloging-in-Publication Data
NATD Advanced Stuoy Institute an Energetics of Drganometallic Specles
(1991 : Cur ia. Portugal)
Energetics of organometallic species : proceedings of the NATD
Advanced Study Insltute an Energetics of Drganometallic Specles held
at Curia. Portugal. September 3-13. 19~1 I edlted by J.A. Martinho
Slmăes.
p. cm. -- (NATD ASI serles, Serles C. Mathematical and
physical sciences ; ne. 367)
Includes bibliegraphical references and lneex.
ISBN 978-94-010-5088-3 ISBN 978-94-011-2466-9 (eBook)
DOI 10.1007/978-94-011-2466-9
1. Organometall ic compounds--Congr~sses. 2. Thermochemlstry-
-Congresses, I. Simoes, J. A. Martinhc. II. Title. III. Series.
QD410.N355 1991
547'.05'0456--dc20 92-9043
ISBN 978-94-010-5088-3
Printed an acid-free paper
AII Rights Reserved
© 1992 Springer Science+Business Media Dordrecht
Originally published by Kluwer Academic Publishers in 1992
No part of the material protected by this copyright notice may be reproduced or
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CONTENTS
Foreword vii
1. HISTORICAL PERSPECTIVE OF ORGANOMETALLIC THERMOCHEMISTRY
H. A. Skinner
2. COMBUSTION CALORIMETRY OF ORGANOMETALLIC COMPOUNDS
G. Pilcher 9
3. ORGANO-f-ELEMENT THERMOCHEMISTRY. IMPLICATIONS FOR REACTIVITY
AND BONDING FROM METAL-LIGAND BONDING ENERGETICS
M. A. Giardello, W. A. King, S. P. Nolan, M. Porchia, C. Sishta,
and T. J. Marks· 35
4. THE ROLE OF BOND ENERGIES IN HYDROCARBON ACTIVATION BY
TRANSITION METAL CENTERS
W. D. Jones·, R. M. Chin, L. Dong, S. B. Duckett,
and E. T. Hessell 53
5. Rh-C BOND DISSOCIATION ENTHALPIES FOR ORGANOMETALLIC DERIVATIVES
OF RHODIUM PORPHYRINS
B. B. Wayland 69
6. SOLUTION THERMOCHEMISTRY OF ORGANOMETALLIC COMPOUNDS USING
PHOTOACOUSTIC CALORIMETRY: ENTHALPIES OF LIGAND EXCHANGE,
METAL-LIGAND BONDS, AND METAL-SOLVENT INTERACTIONS
T. J. Burkey 75
7. ELECTROCHEMISTRY OF SOME ORGANIC AND ORGANOMETALLIC RADICALS
AND THEIR APPLICATION IN THERMOCHEMICAL CYCLES
D. D. M. Wayner 95
8. DERIVATIVE CYCLIC VOLTAMMETRY: APPLICATIONS IN THE INVESTIGATION
OF THE ENERGETICS OF ORGANOMETALLIC ELECTRODE REACTIONS
M. Tilset 109
9. THE USE OF CALORIMETRIC AND SUBLIMATION TECHNIQUES TO STUDY BOND
PROPERTIES IN ORGANOMETALLIC COMPOUNDS
A. S. Carson 131
10. ESTIMATING ENTHALPIES OF SUBLIMATION OF HYDROCARBONS
J. S. Chickos·, D. G. Hesse, and J. F. Liebman 159
vi
11. DERIVATION OF THERMODYNAMIC QUANTITIES FROM KINETIC
MEASUREMENTS IN GAS PHASE SILANE CHEMISTRY
R. Walsh 171
12. BOND ENTHALPY TRANSFERABILITY - IS IT ACHIEVABLE?
J. A. Connor 189
13. ESTIMATES OF THERMOCHEMICAL DATA FOR ORGANOMETALLIC COMPOUNDS
J. A. Martinho Simoes 197
14. BONDING AND SOLVATION ENERGETICS FOR ORGANOMETALLIC GAS-PHASE
MOLECULES AND IONS: EXPERIMENTAL APPROACHES AND THERMODYNAMIC
INSIGHTS
D. E. Richardson 233
15. GAS-PHASE ACIDITIES OF TRANSITION-METAL CARBONYL AND
TRIFLUOROPHOSPHINE HYDRIDES
A. E. Stevens Miller- and T. M. Miller 253
16. BOND STRENGTHS IN TRANSITION METAL CARBONYL ANIONS
L. S. Sunderlin and R. R. Squires- 269
17. FUNDAMENTAL GAS PHASE STUDIES OF THE MECHANISM AND THERMOCHEMISTRY
OF ORGANOMETALLIC REACTIONS
J. L. Beauchamp- and P. A. M. van Koppen 287
18. GUIDED ION BEAM STUDIES OF THE ENERGETICS OF ORGANOMETALLIC
SPECIES
P. B. Armentrout- and D. E. Clemmer 321
19. A GUIDE TO DENSITY FUNCTIONAL THEORY AND ITS PRACTICAL
APPLICATIONS TO THE ENERGETICS OF ORGANOMETALLIC SPECIES
T. Ziegler 357
20. THEORETICAL MODELS FOR ORGANOMETALLIC REACTIONS
M. R. A. Blomberg-, P. E. M. Siegbahn, M. Svensson,
and J. Wennerberg 387
List of Posters and Contributed Oral Presentations 423
List of Participants 425
Subject Index 431
Foreword
An overview of modern organometallic thermochemistry, made by some
of the most active scientists in the area, is offered in this book.
The contents correspond to the seventeen lectures delivered at the NATO
ASI Energetics of Organometallic Species (Curia, Portugal, September
1991), plus three other invited contributions from participants of that
summer school. These papers reflect a variety of research interests,
and discuss results obtained with several techniques. It is therefore
considered appropriate to add a few preliminary words, attempting to
bring some unity out of that diversity.
In the first three chapters, results obtained by classical
calorimetric methods are described. Modern organometallic
thermochemistry started in Manchester, with Henry Skinner, and his
pioneering work is briefly surveyed in the first chapter. The
historical perspective is followed by a discussion of a very actual
issue: the trends of stepwise bond dissociation enthalpies. Geoff
Pilcher, another Manchester thermochemist, makes, in chapter 2, a
comprehensive and authoritative survey of problems found in the most
classical of thermochemical techniques - combustion calorimetry -
applied to organometallic compounds. Finally, results from another
classical technique, reaction-solution calorimetry, are reviewed in the
third chapter, by Tobin Marks and coworkers. More than anybody else,
Tobin Marks has used thermochemical values to define synthetic
strategies for organometallic compounds, thus indicating an application
of thermochemical data of which too little use has been made so far.
Calorimetry is not the only experimental approach to obtain
information on the energetics of chemical reactions in solution:
equilibrium and kinetic studies have been providing a wealth of
important data, as illustrated in chapters 4 and 5. Bill Jones and
coworkers, in chapter 4, include a description of the energy profiles
of hydrocarbon activation by an unsaturated rhodium complex and discuss
the kinetic and thermodynamic selectivities of aromatic C-H activation
viii
versus ~2-arene coordination. Brad Wayland, in chapter 5, makes a
brief survey of the thermochemical results obtained for rhodium (II)
porphyrin complexes. One of the highlights of these data is the
exothermic carbonyl insertion into a Rh-H bond.
The energetics of short-lived species cannot be probed by the
traditional calorimetric techniques. Chapter 6, by Ted Burkey, deals
with the application of photoacoustic calorimetry to thermochemical
studies of transient organometallic unsaturated complexes in solution.
Data obtained by the photoacoustic technique can often be coupled to
redox potentials of radicals and yield values of heterolytic bond
dissociation enthalpies, pK 's, etc.. These relationships are
a
conveniently summarized in a thermochemical mnemonic included in Dan
Wayner's chapter 7. Also included in this chapter are a brief
description of photomodulation voltammetry (a technique used to
determine redox potentials of transient radicals) and its application
to the measurement of bond energies in radical cations. Mats Tilset,
in chapter 8, illustrates the use of another electrochemical technique,
derivative cyclic voltammetry, to probe the energetics of
metal-hydrogen bonds in a number of transition metal-hydride complexes.
Ideally, the energetics of chemical bonds should be referred to the
perfect gas phase. Solution data are extremely useful, since most
important chemical processes occur in solution, and many may provide a
good approximation of gas phase data. Unfortunately, in the case of
organometallic compounds, the evidence for this last assumption is
rather scarce. We know too little about solvation energetics, in
particular about sublimation enthalpies. Efforts to measure or to
estimate these quantities are addressed in chapters 9 and 10. In
chapter 9, by Alexander Carson, the sublimation enthalpies of several
organometallic molecules, obtained with a Knudsen cell, are combined
with combustion calorimetry results to derive bond enthalpy data. Jim
Chickos, Donald Hesse, and Joel Liebman describe, in chapter 10, a
method for the estimation of sUblimation enthalpies of hydrocarbons.
ix
Most results covered by Robin Walsh's contribution, chapter 11, do
not require any assumptions regarding solvation enthalpies, since they
were obtained in the gas phase. Yet, other assumptions are often
necessary to extract thermochemical results from kinetic and
equilibrium experiments. A brief description of these methods and
hypotheses, illustrated with data for silanes and alkanes, is made in
chapter 11.
Chapters 12 and 13 are a sort of an interlude in our exploration of
organometallic energetics. In chapter 12, Joe Connor introduces and,
through a set of selected data, discusses the idea of "bond enthalpy
transferability" as appli~d to transition metal organometallic
compounds. Although we/~now many of the rules that allow us to predict
if two similar bonds in different organic compounds have similar
"strengths" (e.g. by comparing the bond orders and the bond lengths),
other considerations are required when the exercise is attempted for
d-element molecules (e.g. the oxidation state of the metal and the
coordination number). The transferability of bond enthalpies is a very
relevant issue for predicting the energetics of reactions where no
experimental data are available. The estimation of thermochemical data
for organometallic compounds is considered in chapter 13, where a
critical survey of the methods that have been (or can be) used for that
purpose, is made.
Several mass spectrometry techniques provided valuable information
on metal-ligand bonding energetics in neutral and ionic coordinatively
saturated compounds and organometallic fragments. Furthermore, gas
phase data such as ionization and electron attachment energies can be
compared with their solution counterparts, oxidation and reduction
potentials, providing information on solvation energetics. This bridge
between gas phase and solution data is analyzed by David Richardson
(chapter 14) and illustrated for several organometallic and
coordination complexes. It is worth pointing out that Richardson's
basic data, ionization and electron attachment energies, were obtained
from equilibrium and bracketing studies of ion-molecule reactions in a
x
Fourier transform ion cyclotron mass spectrometer cell. FTICR, one of
the favorite techniques for probing gas phase chemistry and
thermochemistry, has also been used by Amy Stevens Miller and Thomas
Miller, to determine the gas phase acidities of a number of transition
metal-hydride complexes (chapter 15). Trends in these acidities are
explained in terms of metal-hydrogen bond dissociation enthalpies and
electron affinities of the organometallic fragment radicals. Solvation
effects on acidities are also addressed by comparing the gas phase
acidities with the solution pK 's of the hydrides.
a
Some of Amy Stevens Miller's acidity data were obtained by studying
ion-molecule reactions in a selected-ion flow tube (SIFT). An
apparatus from the same family, a flowing afterglow-triple quadrupole
mass spectrometer, was used by Lee Sunderlin and Bob Squires to measure
the energy thresholds for CO dissociation in several transition metal
carbonyl anions (chapter 16). In some cases, these results were
coupled with electron affinity data to yield M-CO stepwise bond
dissociation enthalpies in the neutral species. Jack Beauchamp and
Petra van Koppen, in chapter 17, review the contribution of several
other gas phase techniques (ICR, ion beam and the measurement of
kinetic energy release distributions) and theoretical methods to
investigate the thermochemistry and the mechanisms of organometallic
reactions. The measurement of kinetic energy release distributions is
covered in some detail and its application to probe the energetics of
large molecules (such as co-enzyme B ) is emphasized. The survey is
1Z
illustrated with many examples, and includes a "periodic table" of the
trends of atomic metal ion reactivity.
Part of the beauty of the experiments by Peter Armentrout and David
Clemmer (chapter 18) lies in the simplicity of the systems analyzed.
For example, by probing the energetics of "diatomic" species like ML or
ML+, they are able to examine the details of M-L lor M+-L) bonding by
varying M or L. As many of these species are sufficiently "simple" to
be handled by sophisticated theoretical methods, the experimental data
can also be used for the calibration of these methods. The guided ion
