Oxovanadium(IV) and oxovanadium(IV)-barium(II) complexes with heterotopic macrocyclic ligands based on isothiosemicarbazide

The macrocyclisation reaction of 3,3'-(3,6-dioxaoctane-1,8-diyldioxy)-bis(2-hydroxy-benzaldehyde) (1) with S-methylisothiosemicarbazide hydroiodide in the presence of barium triflate, followed by addition of oxovanadium(IV) chloride, yields the dimeric complexes [(VOBaLI)-I-1(I-3)CH3OH](2) (3) and [VOBaL1((CFSO3)-S-3)(2)(CH3OH)(0.5)(H2O)(0.5)](2) (4). Starting from 3,3'-(3,6,9-trioxaundecane-1,11-diyldioxy)-bis(2-hydroxybenzaldehyde (2), and following the same procedure the polymeric complex ([(VOBaLCl)-Cl-2]I-3)}(n) (5) has been obtained. Treatment of 3, 4 or 5 in chloroform with an aqueous solution of guanidinium sulphate leads to VOL1 (6) or VOL2. 2H(2)O (7). Compound 4 has been synthesised in high yield by direct complexation of VOL1 with barium triflate in methanol. The crystal structures of 3, 4 and 5 have been determined by X-ray crystallography. Electronic, mass and EPR spectra are reported. (C) 2001 Elsevier Science B.V. All rights reserved.