Mono- and Trinuclear Nickel(II) Complexes with Sulfur-Containing Oxime Ligands: Uncommon Templated Coupling of Oxime with Nitrile.

Abstract

4,7-Dithiadecane-2,9-dione dioxime forms both violet and purple-black nickel(II) complexes with unexpected structural properties, quite unlike the square-planar chelates formed by its dithiaundecane homologue. Their perchlorate salts were isolated and examined crystallographically. The lilac product [Ni{(Dtox)(CH(3)CNH)(2)}](ClO(4))(2) entails a bis(iminoether) ligand formed by coupling of the dioxime with two moles of acetonitrile. The purple-black complex results from further ligand deprotonation, to yield trinuclear, antiferromagnetic [Ni(3)(Dtox)(DtoxH)(2)](ClO(4))(2).CH(3)CN, which maintains its structure in solution. The first one-electron electrochemical oxidation step is relatively facile for the trimer, yielding a Ni(2)(II)Ni(III) complex, whereas for [Ni{(Dtox)(CH(3)CNH)(2)}](ClO(4))(2) a transient Ni(I) species is accessible. Comment is made on those properties (coordination number, donor type, core charge) of nickel(II) coordination spheres that affect the accessibility of the corresponding nickel(I) and nickel(III) forms. [Ni(3)(Dtox)(DtoxH)(2)](ClO(4))(2).CH(3)CN crystallizes in the monoclinic space group P2(1)/n, with cell parameters a = 12.295(2) Å, b = 17.360(2) Å, c = 20.764(2) Å, alpha = 90 degrees, beta = 94.080(10) degrees, gamma = 90 degrees, V = 4420.7(6) Å(3), Z = 4. [Ni{(Dtox)(CH(3)CNH)(2)}](ClO(4))(2) crystallizes in the rhombohedral space group R&thremacr;, with cell parameters a = 32.954(2) Å, b = 32.954(2) Å, c = 13.477(2) Å, alpha = 90 degrees, beta = 90 degrees, gamma = 120 degrees, Z = 18.