Copper complexes organic bridging

Table 33 Dinuclear Copper(II) Complexes with Bridging Organic Groups...

Complexes 144 and 145 represent the first examples of heterotetrametallic transition metal complexes in which early and late metals are connected by 7t-conjugated organic bridging imits. A striking feature of 144 is that all metals possess different coordination spheres titanium shows a pseudo-tetrahedral environment, copper possesses a planar surroimding, platinum is square-planar coordinated and iron is part of a sandwich structure... 

The crystal structure consists of TTF layers in the (002) planes which alternate with inorganic Cu(hfac)2 layers in the (001) planes. These two layers are linked by conjugated bridge (Fig. 10a). Figure 10b focuses on the organic plane the TTF units form dimers with the shortest S—S contact equal to 3.593(3) A. In one dimer, each TTF belongs to two different complexes with copper ions lying in two... 

NEtH3 and NPhH3) are isomorphous with the corresponding copper(II) complexes, which are known to have chloride-bridged sheets intercalated with the organic cations. 

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. ... 

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