CRYSTAL-STRUCTURE AND MAGNETIC-PROPERTIES OF A COPPER(II)-VANADIUM(IV) COMPLEX OF AN OPEN-ENDED DINUCLEATING LIGAND

The heterodinuclear copper(II)/vanadium(IV) complex, [bpmpCu(Cl)VO(H2O )](ClO4)(2), where bpmp(-) is the ligand pyridylmethyl)amino)methyl]-4 -methylphenolate(1-), has been prepared in a one-pot reaction from Hbp mp, VCl3 and Cu(ClO4)(2) in air. The X-ray structure shows the complex to be monoclinic, space group C2/c with eight cations in a cell of di mensions a=23.445(3), b=16.392(3), c=20.612(3) Angstrom and beta=106.9 55(7)degrees. The structure refined to a final R-value of 0.064 for 33 79 reflections and 504 variables. The copper and vanadium atoms are br idged by the phenolic oxygen atom of bpmp with V-O-phenolate=1.958(6) Angstrom and Cu-O-phenolate=2.361(5) Angstrom. Two dinuclear units are associated via chloride bridging between the Cu atoms with Cu-Cl= 2.2 80(3) and 3.226(2) Angstrom. The vanadium is incorporated as a vanadyl ion and also has a water molecule coordinated. Magnetic susceptibilit y measurements indicate a very weak ferromagnetic coupling (J=0.43 cm( -1)); this probably originates from a Cu ... Cu interaction in the tet ranuclear units. The ESR spectrum of [bpmpCu(Cl)VO(H2O)](ClO4)(2) conf irms the very weak coupling.