DERIVATIVES OF HYDRAZINE AS LIGANDS IN VA NADIUM(IV) AND VANADIUM(V) COMPLEXES - SYNTHESIS AND CRYSTAL-STRUCTURES OF 3 DIMERIC COMPLEXES WITH HYDRAZIDO AND HYDRAZONATO LIGANDS

The complexes [(mu-PhCONNCOPh){VOCl(NHNHCOPh)(2)}]. 5 CH3CN, (1), [(mu -PhCONNCOPh)(V(dbh)}(2)]. 2 CH3CN, (2) and [(VO)(2)(tbh)], (3) have be en prepared by reaction of VCl2(acac)(2), acac = acetylacetonato(1-), and VCl2(acpn), acpn = propylendiimino-bis(acetylacetonato(2-)), with benzoylhydrazine. The structures of the centrosymmetric dimeric molecu les 1-3 have been determined by single crystal X-ray diffraction. 1 an d 2 contain both doubly deprotonated N,N'-dibenzoylhydrazine as bridgi ng, doubly N,O chelating ligand. In 1 the two remaining coordination s ites at the VOCl group are occupied by the hydrazido(1-) ligand [NHNHC OPh](-). 2 is a non-ore vanadium(IV) complex. The coordination geometr y is approximately trigonal prismatic. The pi-back donating effect of the oxo function is substituted by back donation from three negatively charged enolic oxygen atoms. The V-O bond lengths range from 192.0(2) to 193.7(2) pm. 3 contains a unique highly symmetrical octadentate li gand, formed during the synthesis. It is coordinated to two oxovanadin (IV) centers by N,O chelation. The coordination geometry is square pyr amidal.