Homo and heteronuclear complexes of dioxime ligands

The mononuclear fragments [Cu(HDopn)(OH)(2)](+) and [Cu(HPopn)(OH)(2)](+), [H(2)Dopn = 3,3'-(trimethylenedinitrilo)-dibutan-2-one dioximate and H(2)Popn, = 3, 3'-(phenylenedinitrilo)-dibutan-2-one dioximate] were used to prepare four binuclear complexes [(OH2)Cu (Dopn)Cu(ditn)](2+), [(OH2)Cu(Dopn)Ni(ditn)(H2O)](2+) (ditn = diethylenetriamine) and [(OH2)Cu(Popn)Cu(L) (H2O)](2+) (L = 2,2'-bipyridine or 1,10-phenanthroline). Two trinuclear complexes, [{Cu(Popn)(OH2)}(2)M (H2O)(n)](2+) (when M = Cu-II, n = 1; M = Zn-II, n = 2), have been synthesised and characterised by elemental analyses, f.a.b. mass, i.r., electronic, e.s.r. spectroscopy and variable temperature (5-300 K) magnetic susceptibility measurements. A strong antiferromagnetic interaction (J = -545 cm(-1) to -700 cm(-1)) has been found for the binuclear copper(II) complexes. The X-band e.s.r. spectra of these complexes at 300 K and for trinuclear complexes at 120 K indicate square-pyramidal geometry for the copper centres with a (d(x2-y2))(1) ground state. The binuclear complex of copper(II)-nickel(II) centres with antiferromagnetic interaction (J = -107 cm(-1)) is described, and moderately strong zero-field splitting within the quartet state leads to Kramers doublet, as indicated by X-band e.s.r. spectra of this complex. The trinuclear copper(II) complex with an antiferromagnetic interaction (J = -350 cm(-1)) is also described. The heterometallic trinuclear copper(II)-zinc(II)-copper(II) system shows a very weak interaction (J less than or equal to -1 cm(-1)).