摘要:

Cleavage of the M-H bond of transition metal hydrides can result in delivery of a hydride (H−), hydrogen atom (H), or proton (H+) to an organic or organo-metallic substrate. Hydrogen atom transfer from a metal hydride to an olefin is an endothermic reaction; the rate at which different metal hydrides carry out this reaction is mainly dependent on the bond dissociation energy of the M-H bond. Hydrogen atom transfer from a metal hydride to a carbon-centered radical is an exothermic reaction in which the rate is largely determined by steric demands of the ligands of the metal hydride, with thermodynamics playing a less important role. Some neutral metal hydrides can function as hydride donors to carbocations. Anionic metal hydrides also exhibit hydridic reactivity, but in some cases the actual M-H bond cleavage step involves hydrogen atom transfer as a part of a radical chain reaction. Neutral metal hydrides can function as nucleophiles and as weakly coordinating ligands to coordinatively unsaturated metals.

ISSN:0260-3594    

DOI:10.1080/02603599108018617

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The magneticgfactors and the zero field splittings of the4A2,2E,2T1and2T2states, all derived from the (t2)3configuration, are re-examined. In particular the early work of Sugano and Tanabe, and the later, more precise analysis of Macfarlane are compared. The utility of the Hamiltonian applied to a Russell-Saunders multiplet is demonstrated. Some examples of trigonal Cr(III) complexes are used to illustrate outer sphere perturbations as well as limitations in the conventional ligand field model.

ISSN:0260-3594    

DOI:10.1080/02603599108018618

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The transition metal bis-dithiolene complexes (MS4C4X4) can be used as acceptor molecules in π-donor-acceptor-type compounds, or as radical anions in mixed valence compounds. These compounds are in the wide middle ground between the strictly organic or inorganic molecular solids on which extensive research has led to the discovery of molecular superconductors and to the development of new materials and concepts. Novel solid state materials derived from metal bis-dithiolene complexes also exhibit interesting original physical properties. In the (TTF)[MS4C4(CF3)4] series of compounds, depending on the nature of the metal ion, a wide range of novel magnetic phenomena ranging from bulk ferrimagnetism (M = Ni) to spin-Peierls transition (M = Cu and Au) have been observed. Metal bis-dithiolene complexes have also been used for preparing molecular superconductors such as (TTF)[M(dmit)2]2and (Me4N)0.5[Ni(dmit)2] (dmit2-= 1,3-dithiol-2-thione-4,5-dithiolate) in which the conduction mechanisms are quite different from those of the strictly organic molecular superconductors.

ISSN:0260-3594    

DOI:10.1080/02603599108018619

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

This is a scanned image of the original Editorial Board page(s) for this issue.

ISSN:0260-3594    

DOI:10.1080/02603599108018616

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor