Binuclear vanadium sites

Examination of the sfructures of these vanadium phosphates with neutral V/P/0 covalent networks reveals three general stracmral types based on the nuclearity of the vanadium sites phases with mononuclear vanadium polyhedra, those with binuclear vanadium sites, and species exhibiting ID chains or double chains. There can be considerable stmctural variability within these broad categories. Thus, the binuclear core may exhibit corner-, edge-, or face-sharing of vanadium octahedra. Likewise, the chain sfructures may be further distinguished by rotations or inclinations of the relative positions of the basal planes. 

Each phosphate group provides an oxygen atom to bridge the vanadium sites of the confacial bioctahedral unit. Of the remaining three oxygen atoms, one is deployed as a donor to a neighboring comer-sharing binuclear unit and two link... 

Newer types of the dinuclear vanadium(IV) complex catalysts 84 have been developed. The abovementioned dinuclear vanadium complexes possess a VO V linkage whereas the ESR study on the catalyst 84 revealed no V—O—V linkage. The sense of enantioselection by the catalyst 84 of the (R,5,5)-structure is opposite to that of the binuclear complex 78a of the same (R,5,5)-structure. These results suggested two active sites attached to the binaphthyl skeleton in the catalyst 84 performed the dual activation of 2-naphthols in the oxidative couphng to achieve high enantioselectivity ... 

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