Dinuclear metal complexes, novel reactions

BALCH Novel Reactions of Dinuclear Metal Complexes... 

A. L. Balch, Adv. Chem. Ser, 1982, 196, 243-255. Novel Reactions of Dinuclear Metal Complexes. Reactions and Structures of Palladium Complexes Containing Is(diphenylphosphino)methane as a Bridging Ligand. 

The reaction of the coordinatively unsaturated ruthenium amidinates with [Cp RuCl]4 tetramer or [CpRufMeCNlsJPFg provides access to novel amidinate-bridged dinuclear ruthenium complexes (Scheme 146), which in turn can be transformed into cationic complexes or hydride derivatives. In these complexes, a bridging amidinate ligand perpendicular to the metal-metal axis effectively stabilizes the highly reactive cationic diruthenium species. 

This is a remarkable reaction because the transition metal chemistry of N2O is sparse, especially with copper. Most N2O reductases are soluble, periplasmic homodimers however, there are examples of membrane-associated enzymes. " The best characterized N2O reductases are from Paracoccus denitrificans, Pseudomonas nautica, and Pseudomonas stutzeri, and most of the information presented here is derived from experiments on these enzymes. Where comparable data are available, N2O reductases from various organisms appear to be fairly similar, with the exception of the enzyme from Wolinella succinogenes, as noted above. The crystal stractmes of N2O reductase from P. nautica and more recently from P. denitrificans show two distinct copper clusters per subunit a bis-thiolate bridged dinuclear electron-transfer site (Cua), which is analogous to the Cua site in cytochrome c oxidase see Cyanide Complexes of the Transition Metals), and a novel four-copper cluster ligated by seven histidines, the catalytic copper site (Cuz), where N2O is thought to bind and be reduced. Cuz was proposed to be a copper-histidine cluster on the basis of the presence of nine strictly conserved histidine residues, and this was supported by a H NMR study that identified two non-CuA associated resonances that were assigned as copper-histidine N-H protons. ... 

Bis(trifluorosilyl)bis(trimethylphosphine)paIladium was formed by a metal vapor/plasma technique (Scheme 1).[" Stable c -bis(silyl)palladium complexes were prepared from the direct reaction of either hydrosilanes or 1,2-dihydrodisilanes with the novel dinuclear palladium hydride (Scheme 2). A first X-ray crystal structure of the bis(silyl) compound 1 was obtained. ... 

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