Copper binuclear

Understanding of the proton translocation has been complicated by the need to address a steady-state circumstance rather than to consider static states. For example, in the oxidized state in the absence of reductant, the heme-copper binuclear center relaxes to a state that lies outside of the catalytic cycle. With proper consideration of the catalytic cycle according to Wikstrdm and Verkhovsky, Two protons each are pumped during the oxidative and reductive halves of the cycle. This important insight has yet to be carried to the molecular species involved, although an OH" ligand for Cub[II] has been considered, as well as earlier implication of a histidine liganded to Cub. ... 

Mogi, T., T. Hirano, H. Nakamura, Y. Anraku, and Y. Orii (1995). Cur promotes both binding and reduction of dioxygen at the heme-copper binuclear center in the Escherichia coli bo-type ubiquinol oxidase. FEBS Lett. 370, 259-263. 

Ethers in which at least one group is primary alkyl can be oxidized to the corresponding carboxylic esters in high yields with ruthenium tetroxide. Molecular oxygen with a binuclear copper (II) complex " or PdCVCuCVCO " also converts ethers to esters. Cyclic ethers give lactones. " The reaction, a special case of 19-14,... 

Comba and co-workers described a simple and efficient method for the determination of solution structures of weakly coupled binuclear copper(II) complexes.54 The technique involves the combination of molecular mechanics55,56 and EPR spectroscopy. From this standpoint they reported the structure of the complex (29). Using an acyclic tertiary tetraamine ligand, Bernhardt reported57 crystal structure of the complex (30), along with its redox properties. 

Illiopoulos, P. et al., J. Chem. Soc., Dalton Trans., 1986, 437-443 The dihydrated binuclear complexes between copper(II) perchlorate and N-(2-pyridyl)-acetoacetamide and -benzoylacetamide, [Cu2L2(C104)2].2H20, exploded on heating to 260° C. 

A second class of molecules with two unpaired electrons has the two electrons localized, to a first approximation, in different parts of the molecule. We refer to such molecules as biradicals (or, with three or more unpaired electrons, triradicals, etc.). Examples are the dinitroxides (e.g. 1), and certain binuclear vanadium(iv) and copper(n) complexes. 

Considerable improvement was achieved with binuclear copper(II) chelates of type 195 whose ligands are derived from salicylaldehyde and an optically active amino alcohol 91>92>. 

A series of binuclear silver(i) complexes with pyridyl substituted alkyl ligands, 6a and 6b (Figure 4), was reported, as well as their copper(i) and gold(i) analogs.23-25 These binuclear silver(i) complexes were found to be very light and air sensitive and would readily decompose at room temperature in solution. Even when stored under argon in unlit conditions, decomposition would occur within several days. 

Laccase contains four copper atoms that have been classified as type 1 or blue (Tl), type 2 or normal (T2), and type 3 (T3) or coupled binuclear copper sites, where the coppers are antiferromagnetically coupled through a bridging ligand (Fig. 4.4). 

Rate and equilibrium constant data, including substituent and isotope effects, for the reaction of [Pt(bpy)2]2+ with hydroxide, are all consistent with, and interpreted in terms of, reversible addition of the hydroxide to the coordinated 2,2 -bipyridyl (397). Equilibrium constants for addition of hydroxide to a series of platinum(II)-diimine cations [Pt(diimine)2]2+, the diimines being 2,2 -bipyridyl, 2,2 -bipyrazine, 3,3 -bipyridazine, and 2,2 -bipyrimidine, suggest that hydroxide adds at the 6 position of the coordinated ligand (398). Support for this covalent hydration mechanism for hydroxide attack at coordinated diimines comes from crystal structure determinations of binuclear mixed valence copper(I)/copper(II) complexes of 2-hydroxylated 1,10-phenanthroline and 2,2 -bipyridyl (399). 

In addition to the systems just mentioned, recent kinetic and mechanistic studies have included those involving copper(II) (409,410) and zinc(II) (411) species, various binuclear metal(II) complexes of first row transition elements (412-414), especially iron (407), cobalt (415), copper (305,416), and zinc (417,418), yttrium (419,420) and lanthanide (421,422) species, and thorium(IV) (423). 

The reaction of binuclear copper complexes with oxygen as models for tyrosinase activity was also markedly accelerated by applying pressure (106408 ). Tyrosinase is a dinuclear copper protein which catalyses the hydroxylation of phenols. This reaction was first successfully modeled by Karlin and co-workers (109), who found that an intramolecular hydroxylation occurred when the binuclear Cu(I) complex of XYL-H was treated with oxygen (Scheme 5). 

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