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P. Weinberger, O. Costisor, O. Baumgartner, K. Mereiter, W. Linert:
"Homo- and heteropolynuclear coordination compounds of copper and vanadium: structural and vibrational investigations";
Vortrag: 7th International Chemistry Conference in Africa, Durban, Südafrika; 06.07.1998 - 10.07.1998; in: "Programme and abstracts", (1998), S. 10.

N,N´-bis(antipyryl-methyl)-piperazine (BAMP) is a symmetric ligand, in which two kinds of donor atoms - i.e. a carboxylic oxygen and a piperazinic nitrogen - are situated on both sides of the piperazine bridge. The nature of the metal-BAMP-complexes depends on the confirmation of this piperazine bridge. Thus, if piperazine adopts a "chair" conformation, BAMP acts as a bis-bidentate ligand. This is the case in most homo- and heterodinuclear complexes of the type MM´(BAMP)X_n. Only one mononuclear compound was obtained - namely Co(BAMP)(NCS)₄ - and a structure with BAMP acting as tetradentate ligand was proposed. In this case the piperazine adopts a "boat" conformation. With the mixed valence copper(I)-copper(II) complex we present the first confirmation of a dinuclear complex with BAMP acting as tetradentate ligand. Complexes of VO³⁺ or VO²⁺ containing the oxalate ion as bis-bidentate ligand are also known, but they were not studied extensively. Heterodimetallic copper(II)-oxovanadium(IV) oxalates, [(terpy)Cu(ox)(H₂O)].H₂O and [(terpy)₂Cu₂(ox)₂VO(H₂O)](ClO₄)₂.H₂O, have been the subject of many recent studies with the hope of elucidating the mechanism of spin coupling between paramagnetic ions through the brisging oxalate ligand. Bimetallic oxalate complexes in the copper(II)-oxovanadium(IV) system have been synthesized and their ability to act as catalyst for the autoxidation of aliphatic aldehydes has been proved. In all cases stated above it was suggested that the oxalate anion is acting as a bridging bis-bidentate ligand. As part of a continuation of works in this field we want to report the crystal structure and the vibrational features of a new heterometallic, mixed valence compound obtained in the system vanadium - copper - oxalate.