Bis(mercaptoimidazolyl)(pyrazolyl)hydroborato Complexes of Zinc, Cadmium, and Cobalt: Structural Evidence for the Enhanced Tendency of Zinc in Biological Systems to Adopt Tetrahedral M[S4] Coordination

Autor:	David G. Churchill, Brian M. Bridgewater, Tony Hascall, Clare Kimblin, Gerard Parkin
Rok vydání:	2000
Předmět:	Cadmium Molecular Structure Chemistry Inorganic chemistry chemistry.chemical_element Cobalt Ethylenethiourea Zinc Sulfur Inorganic Chemistry Crystallography Zinc Compounds Tetrahedron Pyrazoles Physical and Theoretical Chemistry
Zdroj:	Inorganic Chemistry. 39:4240-4243
ISSN:	1520-510X 0020-1669
DOI:	10.1021/ic000093l
Popis:	The bis(2-mercapto-1-methylimidazolyl)(pyrazolyl)hydroborato derivatives [pzBmMe]2Zn, [pzBmMe]2Co, and [pzBmMe]2Cd have been isolated and structurally characterized by X-ray diffraction. Despite their common [pzBmMe]2M composition, each of these complexes adopts a different structure. Thus, (i) the zinc complex exhibits a tetrahedral Zn[S4] structure in which only the sulfur donors coordinate to zinc, (ii) the cobalt complex exhibits a trigonal-bipyramidal Co[S3NH] structure in which one of the pyrazolyl groups and one of the B-H groups coordinate to cobalt, and (iii) the cadmium complex exhibits a six-coordinate Cd[S4H2] structure in which both B-H groups interact with the cadmium center. These comparisons emphasize that zinc has a greater preference for tetrahedral M[S4] coordination than does either cobalt or cadmium, an observation that is in accord with the prevalent role of zinc in the structural sites of enzymes.
Databáze:	OpenAIRE
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