The Heavy Transition Elements

Metal Complexes Containing n-Bonding Ligands 9.1 Bonding in an Octahedral Metal Carbonyl 9.2 Discussion of the Molecular-orbital Diagram 9.2.1 The eighteen-electron (E.A.N.) rule 9.3 The Bonding in an Octahedral Complex (Using Group Theory) 9.4 General Considerations 9.5 The Binary Carbonyls and their Derivatives 9.5.1 Reactions of the metal carbonyls 9.5 .2 Substitution reactions 9.5.3 Formation of anions and hydrides 9.5 .4 Heteronuclear carbonyls 9.5 .5 Oxidation reactions 9.6 Metal Cyclopentadienyl and Arene Systems 9 .6.1 Bonding in ferrocene 9.6.2 Hydrides and other derivatives 9.7 Other Transition-metal n Complexes 9. 7.1 Transition-metal carborane complexes 9.7.2 n-Allylcomplexes 9.7.3 Cyclobutadiene complexes 9.7.4 Arene complexes 9.7.5 Tropylium complexes 9. 7.6 Cyclo-octatetraene complexes 9.8 Transition-metal Alky1s and Aryls 9.9 The Binary Carbonyls. Synthesis and Structure 9.9.1 The d 5 metals 9.9.2 The d 6 metals 9.9 .3 The d 7 metals 9.9.4 The d 8 metals 9.9.5 The d 9 metals 9.9.6 The d 10 metals 1 0 The Lanthanides ## Preface The study of transition metals and their compounds occupies a prominent place in most first-degree chemistry courses. In many cases considerable attention is paid to the first-row transition series, much less attention to the second-and third-row metals, while the lanthanides and actinides are treated with the utmost brevity. The origin of this imbalance is probably to be found in a combination of two factors. The first is that the industrially important, well-known and abundant transition metals are the 3d metals such as copper, iron and nickel. Secondly, the quantitative aspects of ligand-field theory are more readily applied to the 3d metals than to the 4d, Sd, 4f and Sf metals because of the relative magnitudes of the physical parameters, such as the spin-orbit coupling constant and the crystal-field splitting parameter, that are involved. This book, which is a sequel to a cognate volume t dealing with the 3d metals, gives an account of the 4d, Sd, 4f and Sf metals, which it is hoped will be adequate for any first-degree requirements and for postgraduate courses dealing with general aspects of transition-metal chemistry. The treatment is given in sufficient range and detail to allow considerable latitude to the course organiser and student in their choice of precise topic and level of approach. We have not hesitated to include a high proportion of descriptive chemistry, in the conviction that a sound knowledge of experimental facts forms the basis of any scientific discipline. This style of treatment may also be useful to research workers requiring a general view of some particular area of 4d, Sd, 4f and Sf chemistry; it is not intended, however, to provide a detailed introduction to research. We would like to thank a number of our colleagues, particularly Professor D. C. Bradley, Dr D. M. P, Mingos and Dr P. Thornton for reading portions of the manuscript and making constructive comments. Any remaining errors are our own responsibility. We also wish to thank Mrs H. Matthewman and Mrs T. Gue for their very efficient typing of the manuscript. Finally, we both wish to thank Mrs Eileen Hart for preliminary typing and for much assistance and encouragement. + Complexes and First-Row Transition Elements, by David Nicholls S. A. Cotton F. A. Hart J TiC14(diarsh THE HEAVY TRANSITION ELEMENTS Figure 1.5 The structure of Zr(CF 3 .CO.CH.CO.CF 3 h(TC-C 5 H5 ) (after M. Elder, J. G. Evans and W. A. G. Graham,]. Am. chem. Soc., 91 (1969), 1245) the C5 H5 at one apex (see figure 1.5). At room temperature the n.m.r. spectrum of this compound shows rapid configurational exchange, but at low temperatures the two types of diketonate ligand can be discerned. Infrared and Raman spectra indicate that [MX2 acac 2 ] (M = Zr, Hf; X= Cl, Br) adopt the cis configuration in solution, but, except in the case of replacement of X by bulky alkoxide groups, the two environments of the methyl groups on the acetylacetonate ligands cannot be distinguished by n.m.r. even at -130°. Typical donor atom/group Co-ordination number 3 4 tet 4 planar 5 T.B.P. 5 S.P. Front Matter....Pages i-2 Zirconium and Hafnium....Pages 3-14 Niobium and Tantalum....Pages 15-26 Molybdenum and Tungsten....Pages 27-42 Technetium and Rhenium....Pages 43-58 Ruthenium and Osmium....Pages 59-80 Rhodium and Iridium....Pages 81-106 Palladium and Platinum....Pages 107-136 Silver and Gold....Pages 137-153 Metal Complexes Containing π-bonding Ligands....Pages 154-187 The Lanthanides....Pages 188-219 The Actinides....Pages 220-261 Back Matter....Pages 262-272