3 DINUCLEAR COPPER(II) CARBOXYLATES WITH THE PADDLE-WHEEL CAGE STRUCTURE AS INTERMEDIATES IN COPPER(II) CATALYZED OXIDATIONS OF CARBOXYLIC-ACIDS - X-RAY CRYSTAL-STRUCTURES OF YLACETATO-MU-O,O')BIS(ACETONITRILE-N)DICOPPER(II)] TETRAKIS(ACETONITRILE) IPHENYLACETATO-MU-O,O')BIS(ACETONE-O)DICOPPER(II)] AND -MU-O,O'-CYCLOPENTANE)-BIS(ETHANOL-O)DICOPPER(II)] BIS(ETHANOL)

The synthesis, spectroscopic, magnetic and structural characterization of three new dinuclear copper(II) carboxylates are described. All com pounds exhibit the typical dinuclear paddle-wheel type structure, cons isting of two copper(II) ions in square-pyramidal geometry bridged by four carboxylate anions in the xy plane, and O- or N-donor ligands at the apex. [Tetrakis(diphenyl acetonitrile-N)dicopper(II)]tetrakis(acet onitrile) (1), C68H62Cu2N6O8, crystallizes in the triclinic space grou p <P(1)over bar> (No. 2), with a=10.8941(17), b=11.140(2), c=13.346(3) Angstrom, alpha=69.927(17), beta=78.658(16), gamma=86.819(14)degrees, Z=1, R=0.0438 and R-w=0.0479 for 5188 observed reflections. The -2J v alue of this compound is 330(17) cm(-1), the triplet state exhibiting a rhombic zero-field splitting with \D\=0.353(11) cm(-1) and \E\=0.002 2(2) cm(-1), with g(x)=2.03(1), g(y)=2.05(1) and g(z)=2.34(1). The com pound iphenylacetato-mu-O,O')bis(acetone-O)dicopper(II)] (2), C62H56Cu 2O10, crystallizes in the triclinic space group <P(1)over bar> (No. 2) . The cell dimensions are a=10.8722(6), b=11.4003(8), c=11.6856(10) An gstrom, alpha=94.216(6), beta=104.859(6), gamma=111.193(5)degrees, Z=1 , R1=0.0325 and wR2=0.0795. The -2J value is 303(15) cm(-1), the tripl et state exhibiting a rhombic zero-field splitting with \D\=0.345(10) cm(-1) and \E\=0.0004 cm(-1), with g(x)=2.06(1), g(y)=2.02(1) and g(y) =2.33(1). The dinuclear compound l-1-carboxylato-mu-O,O'cyclopentane)b is(ethanol-O) dicopper(II)]bis(ethanol) (3), C56H70Cu2O12, crystallize s in the triclinic space group <P(1)over bar> (No. 2). The cell dimens ions for 3 are a=10.1013(6), b=11.6013(6), c=12.7596(5) Angstrom, alph a=64.908(4), beta=70.116(4), gamma= 83.079(5)degrees, Z=1, R=0.0311 an d R-w=0.0253. The structure forms an extended chain by hydrogen bondin g from the axial ethanol, via a lattice ethanol, to a carboxylate oxyg en of another dicopper unit. The relatively small -2J value of this co mpound is 284(14) cm(-1), the triplet state exhibiting a rhombic zero- field splitting with \D\=0.346(10) cm(-1) and relatively large \E\=0.0 058 cm(-1) g(x)=2.04, g(y)=2.04 and g(z)=2.33, A(1)=0.065 cm(-1). (C) 1998 Elsevier Science S.A.