Transition metals crystal structure determination

R = R = Cy R = 1-adamantyl, R = CfiH 5. Te2-3,5 5 ). The vanadium analogue of the latter [V N(l-Ad)(C6H3Me2-3,5) 3] " 4 has also been characterized. Furthermore, a more efficient route to [Cr N(SiMe3)2 3] and a new crystal structure determination has been described. Three-coordinate metal amides have been treated in a general review that covers three-coordinate transition metal species with hard ligands. The electronic structure and bonding in tricoordinate amido complexes of transition metals have also been detailed... 

A series of polyether macrocycles (40)-(47) that contain a coordinated reducible transition metal redox-active 16-electron molybdenum nitro-syl Mo(NO) 3+ group have been prepared by us in collaboration with McCleverty and Jones (86,87) (Scheme 14). Compounds (40)-(44) were synthesized from the reactions between [Mo(NO)LX2] (L = tris(3,5-dimethylpyrazolyl)hydroborate X = Cl or I) and the appropriate amine-substituted benzo crown ether. Compounds (45)—(47) were prepared from reactions between [Mo(NO)LI2] and tetra-, penta-, or hexa-ethylene glycol, respectively, in the presence of triethylamine. A crystal structure determination of (45) (88) is shown in Fig. 14. 

Long before the erystal structure of cytochrome c oxidase was solved, the function of this enzyme had already been investigated by using the transition metal sites as spectroscopic probes (Caughey et al., 1976 Malmstr m, 1990 Ferguson-Miller and Babcock, 1996). The information obtained from these spectroscopic investigations initiated prior to the crystal structure determination will be summarized. 

The tropolones form transition-metal complexes of high affinity constants, for example [M(77 )3] with M = Co(n), Ni(H) and Zn(H), but M(77 )2 with M = Cu(II)2 . Moreover, these compounds form complexes with heavy metals (Os, Ir, Pt, Mo and W) , the lanthanides(in) and main-group metal ions (Ga, In, Sn, Sb and Pb) many have crystal structures determined and some show biological activities and potential... 

Blandeau, L., Ouvrard, G., Calage, Y., Brec, R., and Rouxel, J. 1987. Transition-metal dichalcogenides from disintercalation processes. Crystal structure determination and Mossbauer study of Li2FeS2 and its disintercalates I. i.l CS2 (0.2 < x <2). Journal of Physics C 20,4271 282. 

The validity of the modified model has been tested by several complete crystal-structure determinations. Up to the present, almost all the single-crystal studies have been carried out with compoimds of the stoichiometry Ms [MB(CN)6]2(M- = Mn2+, Cd +j M = Co +, Cr3+, Ir +). The compound CsaLiCo(CN)6 studied by Wolberg 50) is not considered as a pol5muclear cyanide in this context, being neither a transition metal nor a metal of class B 34). Despite great structural similarities with the Prussian blue analogs, it is rather an alkaline salt of the mononuclear cyanocobaltate III). This distinction is, of course, arbitrary. 

In the absence of crystal structure determination, the well-known magnetic criteria for bond configuration are sometimes useful, since the magnetic moment indicates the number of unpaired electrons in a transition metal complex. Tetrahedral cuprous and divalent planar nickel complexes. 

The crystal-structure determination of bis-(5,5-diethylbarbiturato)bisimi-dazolecobalt(n) is the first of a transition-metal complex in which a drug-active barbiturate is a ligand. Each cobalt atom lies on a crystallographic C2 axis and is surrounded by a tetrahedral arrangement of four nitrogen... 

Apart from the pioneering researches of Bradley and co-workers, who studied the controlled hydrolysis of the alkoxides of some early transition metals, there was little interest in the metal oxo-alkoxides until the sol-gel technique was developed for the conversion of metal alkoxide precursors into metal oxides and heterometal oxides (Chapter 7) A concise review of the chemistry of metal oxo-alkoxides published by Mehrotra and Singh" reveals the rapid growth of interest in this field. The most notable feature has been the dramatic increase in the number of crystal structure determinations in recent years. However, our knowledge of the mechanism of formation of metal oxo-alkoxides leaves much to be desired. 

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