Homo and heteronuclear complexes of dioxime ligands

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The mononuclear fragments [Cu(HDopn)(OH)2]+ and [Cu(HPopn)(OH)2]+, [H2Dopn = 3,3′-(trimethylene- dinitrilo)-dibutan-2-one dioximate and H2Popn, = 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)}2M (H2O)n]2+, (when M = CuII, n = 1; M=ZnII, n = 2), have been synthesised and characterised by elemental analyses, f.a.b. mass, i.r., electronic, e.s.r. spectroscopy and variable temperature (5–300K) 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 300K and for trinuclear complexes at 120K indicate square-pyramidal geometry for the copper centres with a (dx2−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 ≤ −1 cm−1).

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