DINUCLEAR PADDLE-WHEEL COPPER(II) CARBOXYLATES IN THE CATALYTIC-OXIDATION OF CARBOXYLIC-ACIDS - UNUSUAL POLYMERIC CHAINS FOUND IN THE SINGLE-CRYSTAL X-RAY STRUCTURES OF ANE-1-CARBOXYLATO-O,O')BIS(ETHANOL-O)DICOPPER(II)] AND -O'-1'-O')-(MU(3)-DIPHENYLACETATO-1-O-2-O'-2'-O')]

The X-ray structures and spectroscopic and magnetic properties of ne-1 -carboxylato-O,O')bis(ethanol-O)dicopper(II)], 1, and -O':1'-O')(mu(3) -diphenylacetato-1-O:2-O':2'-O')], 2, two extended-chain copper(II) ca rboxylates with dinuclear paddle-wheel subunits, are reported. 1 cryst allizes in the triclinic space group P (1) over bar, with a = 6.8873(3 ) Angstrom, b = 11.7367(6) Angstrom, c = 13.7899(7) Angstrom, alpha = 107.076(4)degrees, beta = 93.545(4)degrees, gamma = 103.967(4)degrees, Z = 1. The Cu...Cu distance is 2.6009(4) Angstrom, and the Cu...carbo xylate O distances are in the range 1.937(2)-1.962(2) Angstrom. The et hanol at the apex forms an unsymmetrical bifurcated H bond to two carb oxylate oxygens of another dinuclear unit with O...O distances 2.980(3 ) and 3.108(3) Angstrom, thereby extending the structure along the a-a xis. The magnetic structure consists of isolated antiferromagnetically coupled dinuclear copper units, with a -2J value of 242 cm(-1), in co ncurrence with the EPR parameters, viz., g(x) = 2.03(1), g(y) = 2.07(1 ), g(z) = 2.35(1), A(parallel to) = 0.064(2) cm(-1), D = 0.316(15) cm( -1), E = 0.005(1) cm(-1). The -2J value is the smallest value measured for dinuclear copper carboxylates with oxygen-donor ligands at the ax ial position and no electron-withdrawing carboxylate R groups. 2 cryst allizes in the monoclinic space group P2(1)/c, with a = 15.953(2) Angs trom, b = 5.385(6) Angstrom, c = 28.322(10) Angstrom, beta = 120.22(3) degrees, Z = 2. The compound contains tetrakis(diphenylacetato)dicoppe r(II) units, forming a polymeric structure along the b-axis by axial c oordination of a carboxylate oxygen to copper of a subsequent dinuclea r unit, at 2.323(11) Angstrom. The intradimer Cu...Cu distance is 2.59 4(4) Angstrom; the interdimer Cu...Cu distance is 3.425(5) Angstrom. T he -2J value of 321 cm(-1) was interpreted as originated from isolated antiferromagnetically coupled dinuclear copper units. The EPR paramet ers are g(x) = 2.07(1), g(y) = 2.02(1), g(z) = 2.33(1), D = 0.347(10) cm(-1), E = 0.0034(5) cm(-1). The dinuclear subunits are likely candid ates for the catalytically active Cu species in copper-(II)-catalyzed oxidation of carboxylic acids.