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 [VOBaL1I(I3)CH3OH]2(3) and [VOBaL1(CF3SO3)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 {[VOBaL2Cl](I3)}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 VOL2·2H2O (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.