摘要:

Metallothionein is an intensively studied protein, which binds a variety of essential, toxic, and pharmacologically active metals, including Zn, Cd, Au, and Pt. Until recently, attention focused primarily on its biological properties and static features of its chemistry. It is now apparent that metallothionein is a remarkably reactive protein in metal exchange and ligand substitution reactions and in its interactions with a number of electrophilic compounds, which are both metallic and organic in nature. This unique behavior finds its basis in the dynamic character of its metal—ligand structure, which is sensitively probed by113Cd NMR techniques. In an effort to relate the chemistry of metallothionein to its cellular activities, it is shown that the kinetic reactivity of the metal binding sites of metallothionein distinguishes it from other typical metalloproteins involved in enzyme catalysis. The rich inorganic chemistry of this structure is clearly important for some of its known functions and is suggestive of other novel roles for this protein in cells.

ISSN:0260-3594    

DOI:10.1080/02603598908035801

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The uniquely featured overall Re═Re double bond structure in some classes of Re3clusters is critically analyzed. Perturbation MO theory, fragment frontier orbitals and other qualitative concepts based on extended Hückel calculations are applied to the well known family of clusters whose precursor is the Re3Cl12−3cluster. Twelve electrons from three d4Re(III) metals are populating σ and π⊥MO levels whose distribution assumes the character of either σ and π⊥aromaticity. In particular the π⊥aromaticity of six electrons distributed over three rather than six atomic centers is attributable to the availability of metal dδorbitals. Similarities and differences between the most classical aromatic system, i.e., benzene, are pointed out, π⊥aromaticity is also the most stabilizing factor in the class of alkylated clusters derived from Re3Cl9[e.g., Re3(CH3)9]. Here the metal electron deficiency [total electron count = 30] is partially overcome byagostic interactionsbetween the metal atoms and the C─H bonds of the bridging CH3groups which then become formal four electron donors. These latter interactions are proved to be at work by closely analyzing available structural data and by calculating their stabilizing effect at EHMO level. Finally, the reported compound Re3(PEt2Ph)2(CH3)6(μ-CH3)3is critically analyzed and a possible alternative formulation is forwarded.

ISSN:0260-3594    

DOI:10.1080/02603598908035802

出版商:Taylor & Francis Group    

年代:1989

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:10.1080/02603598908035800

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor