Photochemistry and Photophysics of Metal Complexes

364 Pages·1994·11.52 MB·English

by  D. M. Roundhill (auth.)

Photochemistry and
Photophysics of
Metal Complexes
MODERN INORGANIC CHEMISTRY
Series Editor: John P. Fackler, Jr.
Texas A&M University
CARBON-FUNCTIONAL ORGANOSILICON COMPOUNDS
Edited by Vac1av Chvalovsky and Jon M. Bellama
GAS PHASE INORGANIC CHEMISTRY
Edited by David H. Russell
HOMOGENEOUS CATALYSIS
WITH METAL PHOSPIDNE COMPLEXES
Edited by Louis H. Pignolet
INORGANOMETA LLIC CHEMISTRY
Edited by Thomas P. Fehlner
THE JAHN-TELLER EFFECT AND
VIBRONIC INTERACTIONS IN MODERN CHEMISTRY
I. B. Bersuker
METAL INTERACTIONS WITH BORON CLUSTERS
Edited by Russell N. Grimes
MOSSBAUER SPECTROSCOPY
APPLIED TO INORGANIC CHEMISTRY
Volumes 1 and 2 • Edited by Gary J. Long
Volume 3 • Edited by Gary J. Long and Fernande Grandjean
MOSSBAUER SPECTROSCOPY
APPLIED TO MAGNETISM AND MATERIALS SCIENCE
Volume 1 • Edited by Gary J. Long and Fernande Grandjean
ORGANOMETALLIC CHEMISTRY OF THE
TRANSITION ELEMENTS
Florian P. Pruchnik
Translated from Polish by Stan A. Duraj
PHOTOCHEMISTRY AND PHOTOPHYSICS OF METAL COMPLEXES
D. M. Roundhill
A Continuation Order Plan is available for this series. A continuation order will bring deli very
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Photochemistry and
Photophysics of
Metal Complexes
D. M. Roundhill
Tulane University
New Orleans, Louisiana
Springer Science+Business Media, LLC
Library of Congress Cata1og1ng-1n-Pub1IcatIon Data
RoundhiU, D. M.
Photochemistry and photophysics of metal complexes / D.M.
Roundhi11.
p. cm. — (Modern Inorganic chemistry)
Includes bibliographical references and index.
ISBN 978-1-4899-1497-2
1. Photochemistry. 2. Metal complexes. 3. Transition metal
complexes. I. Title. II. Series.
QD730.T73R68 1994
546'. 6—dc20 94-26736
CIP
ISBN 978-1-4899-1497-2 ISBN 978-1-4899-1495-8 (eBook)
DOI 10.1007/978-1-4899-1495-8
©1994 Springer Science+Business Media New York
Originally published by Plenum Press, New York in 1994
Softcover reprint of the hardcover 1st edition 1994
All rights reserved
No part of this book may be reproduced, stored in a retrieval system, or transmitted in
any form or by any means, electronic, mechanical, photocopying, microfilming, recording,
or otherwise, without written permission from the Publisher
Preface
This book is intended as both a reference source and as a teaching text. Inorganic
photochemistry has now reached a stage of development where the subject can be
taught as a special topics course. This book introduces the student to a broad range
of topics in this subject, and yet gives a sufficient number of general references that
the student can use it to gain a deeper understanding of an individual topic.
The field of inorganic photochemistry is one that is too broad to be covered
comprehensively in a single volume. On one end of the range are the photochemical
reactions that are primarily used for synthetic purposes, whereas on the other end
there are the detailed photophysical studies on an individual metal complex that
develop a detailed understanding of its ground and excited states. The content of
this book places most of its emphasis on the photochemical aspects of the field. The
photophysical aspects are covered when it clearly is an integral part of developing
an understanding of a particular type of photoreaction.
Another emphasis of this book is in the area of applications. The understanding
of the photochemistry and photophysics of metal complexes has reached a stage of
development where particular metal and ligand combinations can be designed and
chosen for individual applications. Throughout this book an effort is made to make
the reader aware of the possible uses of particular properties of a complex, and
examples are given of the potential technological applications of these features.
This book is designed to meet a need that is not being presently met. Some
books cover specialized topics such as organometallic photochemistry and photo
catalysis, whereas others are edited volumes that place an emphasis on particular
aspects of the subject. This book is designed to give a balanced coverage of all
aspects of the photochemistry and photophysics of metal complexes, and to leave
the reader with an overall appreciation of the subject.
I wish to acknowledge helpful discussions with Drs. Joel Mague, Russ
Schmehl, and Gary McPherson here at Tulane, and with Glen Crosby and Harry
Gray, who convinced me that platinum dimers may have some interesting photo-
v
vi Preface
chemistry. I gratefully acknowledge exceptional secretarial assistance from Mar
garet Overstreet and Linda Chevalier, along with unfailing technical assistance
from Ray Hoff in the preparation of the manuscript. I also acknowledge the
hospitality provided by Dr. John Fackler at Texas A & M University during the later
stages of the writing of this book. As always, in undertaking a project such as this,
the support of one's family is critically important in bringing it to a successful
conclusion.
Contents
1. Principles of Photochemistry of Metal Complexes
1.1. Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2. Electronic Excitation . . . . . . . . . . . . . . . . . . . . . . . .. 2
1.3. State Energy Diagrams . . . . . . . . . . . . . . . . . . . . . . .. 3
1.4. Energy and Wavelength. . . . . . . . . . . . . . . . . . . . . . .. 4
1.5. Singlet and Triplet States. . . . . . . . . . . . . . . . . . . . . .. 6
1.6. Excited State Dynamics ....................... 7
1.7. Franck-Condon Principle ...................... 9
1.8. Radiative Lifetimes . . . . . . . . . . . . . . . . . . . . . . . . . . 10
1.9. Quantum Yields ............................ 11
1.10. Actinometry .............................. 12
1.11. Quenching Rates and Mechanisms . . . . . . . . . . . . . . . . . . 13
1.12. Excimers and Exciplexes ....................... 15
1.13. Reactions of Excited States ...................... 16
1.13.1. Energy Transfer . . . . . . . . . . . . . . . . . . . . . . . . 16
1.13.2. Photoinduced Electron Transfer ............... 17
1.13.3. Atom Transfer ......................... 20
1.14. Spectrochemical Series and Group Theory. . . . . . . . . . . . 20
1.15. Transition Metal Complexes . . . . . . . . . . . . . . . 22
Review Literature. . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
2. Photochemistry of Complexes of First-Row Transition Metals
2.1. Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
2.2. Photoreactions of Complexes of Chromium(lII) . . . . . . . . . . . 26
2.2.1. Photoaquation Reactions . . . . . . . . . . . . . . . . . . . . 27
2.2.2. Photosubstitution Reactions . . . . . . . . . . . . . . . . . . 30
2.2.3. Photoracemization Reactions ................. 31
2.2.4. Photochemistry of Polypyridyl
Complexes of Chromium(III) ................. 32
2.3. Theories for Photochemical Substitution Reactions of
Chromium(III) Complexes . . . . . . . . . . . . . . . . . . . . . . 37
vii
viii Contents
2.4. Photoreactions of Complexes of Cobalt(III) . . . . . 42
2.4.1. Photosubstitution and Photoredox Reactions. 42
2.4.2. Photoisomerization Reactions 46
2.4.3. Photoreactions of Bimetallics . . . . . 48
2.4.4. Photohomolysis Reactions . . . . . . 49
2.5. Photoreactions of Complexes of Copper(I) . 49
2.5.1. Monomeric Complexes ....... . 49
2.5.2. Tetrameric and Cluster Complexes . . 53
2.5.3. Binding to DNA ............ . 55
2.6. Photoreactions of Complexes of Copper(ll) . 56
2.7. Photoreactions of Complexes ofZinc(II) ... 56
2.8. Photoreactions of Complexes of Nickel(lI) . 58
2.9. Manganese-Based Photosystems for the
Conversion of Water into Oxygen 58
Review Literature 60
References . . . . . . . . . . . . . . . . 61
3. Photochemistry of Monomeric Complexes of
Second-and Third-Row Transition Metals
3.1. Photoreactions of Complexes of Second-
and Third-Row Transition Metals. . . . . 67
3.2. Cyanide Complexes . . . . . . . . . . . . . . . . . . . . . 68
3.2.1. Molybdenum and Tungsten Octacyanide Complexes 68
3.2.2. Platinum Tetracyanide Complexes 69
3.2.3. Metal Hexacyanide Complexes . . . . . . 72
3.2.4. Gold Dicyanide Complexes. . . . . . . . 72
3.3. Complexes with Nitrogen-Containing Ligands. 73
3.3.1. Dinitrogen, Nitride, and Imide Complexes. 73
3.3.2. Ammine Complexes. . . . . . . . . . . . . 74
3.3.3. Nitrogen-Based Delocalized and Heterocyclic Ligands 78
3.4. Tertiary Phosphine Complexes ............... . 83
3.4.1. Photogeneration of Reactive, Coordinately Unsaturated
Phosphine Complexes. . . . . . . . . . . . . . . . . . 88
3.4.2. Photochemical Generation of Hydrogen from Alcohols 88
3.4.3. Photocarbonylation of Hydrocarbons. . . 91
3.4.4. Photocatalytic Hydrogenation of Alkenes 94
3.4.5. Photochemical Reduction of Water ... 96
3.5. Oxides and Complexes with Oxygen Ligands 97
3.5.1. Oxide Complexes .. 97
3.5.2. Oxalate Complexes . . . . . . . . . . . .100
Contents ix
3.6. Complexes with Sulfur Donor Ligands. . . . . . . . . . . . . . . 102
3.6.1. Sulfide Complexes . . . . . . . . . . . . . . . . . . . . . . 102
3.6.2. Thiolate Complexes ..................... 102
3.6.3. Catalysis with Sulfides. . . . . . . . . . . . . . . . . . . . 103
3.7. Halide Complexes ......................... 105
3.7.1. Platinum Halides . . . . . . . . . . . . . . . . . . . . . . . 105
3.7.2. Iridium and Gold Halides .................. 107
3.8. Pseudohalide Complexes . . . . . . . . . . . . . . . . . . . . . . 108
3.9. Hydride Complexes ......................... 108
Review Literature. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
References ................................ 111
4. Photochemistry of Dimeric and Multimetallic Complexes
of Second-and Third-Row Transition Metals
4.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
4.2. Linearly Bridged Dimers . . . . . . . . . . . . . . . . . . . . . . 117
4.3. Binucleating Ligand Bridged Dimers . . . . . . . . . . . . . . . . 120
4.4. Molecular Orbital Model . . . . . . . . . . . . . . . . . . . . . . 122
4.5. Diphosphite Complexes . . . . . . . . . . . . . . . . . . . . . . . 124
4.5.1. Excited State Electron Transfer .. . . . . . . . . . . . . . 125
4.5.2. Excited State Atom Transfer . . . . . . . . . . . . . . . . . 127
4.5.3. Excited State Reactions with Alkenes and Alkynes . . . . . 132
4.5.4. Exciplex Formation and Electrochemiluminescence .... 133
4.6. Methylenebis(Phosphito) Complexes. . . . . . . . . . . . . 133
4.7. Tertiary Phosphine Complexes ................... 134
4.7.1. Dirhodium Complexes .................... 134
4.7.2. Dipalladium(O) and Diplatinum(O) Complexes ....... 135
4.7.3. Digold(I) Complexes. . . . . . . . . . . . . . . . . . . . . 138
4.7.4. Higher Oligomers ...................... 140
4.8. Pyrazine and Pyrazole Complexes ................. 144
4.9. Photochemistry of Metal-Metal Bonded Dimers and Clusters .. 147
4.9.1. Singly Bonded Dimers . . . . . . . . . . . . . . . . . . . . 148
4.9.2. Quadruply Bonded Dimers .................. 151
4.9.3. Halide Cluster Complexes . . . . . . . . . . . . . . . . . . 154
4.9.4. Hetero-and Isopolymolybdates and Tungstates . . . . . . . 155
Review Literature. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159
References ................................ 160
5. Photochemistry, Photophysics, and Photo redox
Reactions of Ru(bpy)~+ and Related Complexes
5.1. Introduction ............................. 165