Hydrides polynuclear metal complexes

Acknowledgments. Like editors of previous volumes of this series, I am indebted to many colleagues for contributions to this work. First there are Wolfgang Beck in Munich, Ekkehard Lindner in Tubingen, and John R. Shapley in Urbana, who assisted me in the selections and solicitations for three special collections transition metal complexes containing weakly bonded anions (Chapter 3), metalocyclic complexes (Chapter 4), and polynuclear transition metal complexes (Chapter 5), respectively. Each has contributed a preface for the chapter he helped to form, following the pattern set in Volume XII when Alan G. MacDiarmid invited E. C. Ashby and myself to form a chapter on metal hydrides. As a consequence of such efforts, more than two-thirds of this volume consists of invited preparations. 

A variety of factors contribute to the great current interest in l polynuclear metal hydride complexes. These include the novel geometries found in these systems and their usefulness as models for the bonding of hydrogen to metals, such as may occur in catalysis (i) or hydrogen-storage applications (2). A comprehensive review of metal hydride complexes, in which polynuclear species are included, has been published by Kaesz and Saillant (3). 

In this chapter we have examined examples of polynuclear metal carbonyl complexes as well as simple metal carbonyl hydrides. Consider now the polynuclear carbonyl hydride complex, H,Os,(CO)i2- Rationalize the formulation of this species. From your application of the 18-electron rule, what can you say about the structure of this molecule1 How is it similar to or different from the complex Os COln shown in Figure 5.9 (See Churchill M. R. Wasserman, H. J. Iticrg, Chen. 1980, 19, 2391-2395.)... 

Asymmetric Synthesis by Homogeneous Catalysis Carbonyl Complexes of the Transition Metals Hydride Complexes of the Transition Metals Organic Synthesis using Transition Metal Complexes Containing tt-Bonded Ligands Polynuclear Organometallic Cluster Complexes. 

Hou, Z.M., Nishiura, M., and Shima, T. (2007) Synthesis and reactions of polynuclear polyhydrido rare earth metal complexes containing (C5Me4SiMe3)LnH2 units a new frontier in rare earth metal hydride chemistry. European Journal of Inorganic Chemistry, 2535. 

The vast majority of known polynuclear metal hydride complexes contains bridging hydride ligands. Obviously, the possibility of this bonding mode constitutes the main peculiarity of polynuclear compounds in comparison to mononuclear hydrides. Some representative examples of dinuclear complexes containing up to four hydride bridges are shown in Scheme 18.[54-56]... 

Polynuclear hydride complexes include either homodinuclear (Ir2) and heterodinuclear (IrM) species with one, two, or three bridging hydrides. Polynuclear hydrides without H ligands in bridging position are much more unusual, an example being [ Cp Ir(CO)H 2] 203, a compound in which the Ir-Ir bond is not sustained by any bridging ligand. A short metal-metal separation of 2.730(1) A was determined by X-ray crystallography. ... 

This report deals with those publications from 2000 that described advances in metal carbonyl chemistry. This includes those studies that explore the chemistry of the simple metal carbonyls themselves [such as Mo(CO)6 and Fe(CO)s], metal carbonyl halides [e.gf. Mn(CO)sBr], pseudohalides le.g. Mn(CO)5(CN)] and hydrides [e.g. Re(CO)5H], This section is not restricted to mononuclear species. Indeed, carbonyl complexes containing more than one metal atom have formed a large part of this report for many years and the percentage of polynuclear carbonyl complexes is, if anything, increasing. 

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