THE PREPARATION AND SYNTHETIC POTENTIAL OF CHLOROVANADIUM-V AND CHLOROVANADIUM-IV COMPLEXES SUPPORTED BY ENAMINES AND BIS(ENAMINES)

The reaction between VOX3 and functionalised enamines ( Schiff bases) leads to oxovanadium(V) complexes of composition VO(Cl) enam (1) in th e case of X = Cl, and VO(OiPr)(HOiPr)enam (2) for X = OiPr, enam repre sents an ONO(2-) donor set. Type 2 complexes can also be obtained by r eplacing Cl in 1 by OR. Oxovanadium(IV) complexes VO(H2O) enam (3) of Schiff bases with an amino acid moiety form in aqueous solutions conta ining the vanadyl ion and the two Schiff base components. Treatment of 3 with SOCl2 affords cis-[VCl2(enam)] (4), which can further be conve rted to the non-ore complex V(dimethylmalonate)enam (5). The bis(enami ne) (double Schiff base) formed between (1S,2S)-1,2-diphenyl-1,2-diami noethane (SS-dpen) and two equivalents of o-vanillin (van) in the pres ence of VO2+ generates the complex VO(van-SS-dpen) (6), which yields t rans-[VCl2(van-S,S-dpen)] (7) on treatment with SOCl2. 7 reacts with d ilithium benzilate to form the non-ore complex V(benzilate) (van-S,S-d pen) (8). 6 and 7 have been structurally characterised by X-ray diffra ction analysis. 6 . H2O . CH2Cl2: space group P1, a=9.734(2), b=11.833 (2), c=13.720(4) Angstrom, alpha=72.03(2), beta=83.81(2), gamma=80.26( 2)degrees, Z=2. 7.2.5CH(2)Cl(2): space group P1, a=9.555(6), b=13.581( 5), c=15.934(9) Angstrom, alpha=106.73(4), beta=107.00(5), gamma=102.7 9(4)degrees, Z=2. The water molecule in 6 is linked to four oxygens by hydrogen bonds. In 80% of the pair (V1 and V2) of molecules 6 in the asymmetric unit, the vanadyl groups oppose each other. In 20% of V2, t he vanadyl group is inverted, giving rise to a weak V2=O ... V1 intera ction of 2.330 Angstrom. (C) 1998 Elsevier Science S.A.