Transition metal hydrides chemistry

As a result of the recognized role of transition metal hydrides as l reactive intermediates or catalysts in a broad spectrum of chemical reactions such as hydroformylation, olefin isomerization, and hydrogenation, transition metal hydride chemistry has developed rapidly in the past decade (J). Despite the increased interest in this area, detailed structural information about the nature of hydrogen bonding to transition metals has been rather limited. This paucity of information primarily arises since, until recently, x-ray diffraction has been used mainly to determine hydrogen positions either indirectly from stereochemical considerations of the ligand disposition about the metals or directly from weak peaks of electron density in difference Fourier maps. The inherent limi-... 

R. A. Schunn Systematics of transition metal hydride chemistry, pp. 203-269 (394). 

One of the most interesting aspects of transition metal hydride chemistry is the relationship between this ligand and the rapidly developing chemistry of the dihydrogen ligand, H2. 

During the last 10 years, numerous co-workers have contributed with their skills and efforts to the development of the transition metal hydride chemistry in our group. Space does not permit a full mention of all the individuals. The... 

The DQCC values can be experimentally determined from solid - state NMR spectra [12], in NMR experiments with liquid crystal solvents [13] and also by microwave spectroscopy and nuclear double resonance [14]. However, the application of these techniques for transition metal hydrides seems to be problematic for different practical reasons. We show here that the DQCC values can also be determined by T, relaxation experiments on the D - derivatives of transition metal hydrides in solution. It is remarkable thatT, relaxation studies on H nuclei played a great role for the development of the transition metal hydride chemistry and led to the development of excellent methods providing reasonable geometric descriptions of the MH or M(H2) moieties in solution [15, 16]. 

R. Bau, "Transition Metal Hydrides," ddvances in Chemistry Series, Vol. 167, American Chemical Society, Washington, D.C., 1978. 

After graduating from Mikunigaoka High School, Osaka, he studied chemistry at the University of Tokyo from 1968 to 1972 and continued research on hydrido complexes and transition metal hydrides to earn the Dr. sc. degree under the supervision of Professor Yukiyoshi Sasaki in 1977. As a postdoctoral fellow, he worked with Professor John D. Corbett at the Ames Laboratory from 1977 to 1979, and with Professor Arndt Simon at Max-Planck-Institut fur Festkorperforschung, Stuttgart, Germany from 1979 to 1981. In... 

Usui, Y, Hrrano, M., Fukuoka, A. and Komiya, S. (1997) Hydrogen abstraction from transition metal hydrides by gold alkoxides giving gold-containing heterodinuclear complexes. Chemistry Letters, 26, 981. 

Ojima, I. Eguchi, M. Tzamarioudaki, M. Transition Metal Hydrides Hydrocarboxylation, Hydroformylation, and Asymmetric Hydrogenation. In Wilkinson, G. Stone, F. B. A. Abel, E. W., Eds., Comprehensive Organometallic Chemistry 2, Vol. 12, Pergamon, Oxford, 1995, Chapter 2. 

Although orbital hybridizations and molecular shapes for hypovalent metal hydrides of the early transition metals and the normal-valent later transition metals are similar, the M—H bonds of the early metals are distinctly more polar. For example, metal-atom natural charges for YH3 (+1.70), HfH4 (+1.75), and TaHs (+1.23) are all significantly more positive than those (ranging from +0.352 to —0.178) for the homoleptic hydrides from groups 6-10. Indeed, the empirical chemistry of early transition-metal hydrides commonly reveals greater hydricity than does that of the later transition-metal hydrides. 

CO formation on copper electrodes appears to be accompanied by hydride formation as well [103]. In Sch. 3, the surface bound CO is reduced by a hydride transfer reaction to form a formyl species as shown in step 2. There are precedents in organometallic chemistry for late transition metal hydrides reducing bound CO [105-109]. Protonation of the adsorbed formyl in step 3 results in the formation of a hydroxy carbene species [110, 111]. This hydroxycarbene species could be considered to be an adsorbed and rearranged form of formaldehyde, and the reduction of formaldehyde at a copper electrode has been reported to form hydrocarbons [102]. However, reduction of... 

This volume summarizes recent results of some of the leading investigators in trahsition metal hydride research. Readers interested in more extensive background material are urged to consult some of the many excellent books on the subject, such as Transition Metal Hydrides edited by E. L. Muetterties (Marcel Dekker, Inc., New York, 1971), which covers covalent metal hydride complexes, and Metal Hydrides edited by W. M. Mueller, J. P. Blackledge, and G. G. Libowitz (Academic, New York, 1968), which comprehensively covers work in binary and ternary metal hydrides. Also available in the covalent metal hydride area are excellent reviews by Ginsberg [Transition Metal Chemistry (1965) 1,112], and Kaesz and Saillant [Chemical Reviews (1972) 72, 231]. In this book we have not tried to be comprehensive rather, our purpose is to update recent developments in both major areas of metal hydride research. 

Main group hydrides are of particular interest in themselves but are relevant to coordination chemistry only to the extent that they are used to prepare transition metal hydrides or act as ligands. 

At the same time, we believe that the available now lessons of the chemistry of transition metal hydrides make it possible to avoid some mistakes in another field of inorganic chemistry related with hydrogen accumulation. 

Thus, the numerous and instructive lessons of the well-developed field of science - chemistry of transition metal hydrides - allow to treat the results obtained for non-traditional materials more soberly. At the same time, these lessons call us to new enterprises. 

P. B. Armentrout, and L. S. Sunderlin, Gas-Phase Organometallic Chemistry of Transition Metal Hydrides, in Transition Metal Hydrides (Ed. A. Dedieu, VCH Publishers, New York, 1992, Chap. 1.4). 

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