[CR(BIPY)(C2O4)(2)](-) - A VERSATILE BUILDING-BLOCK FOR THE DESIGN OFHETEROPOLYMETALLIC SYSTEMS - CRYSTAL-STRUCTURES OF BACR2(BIPY)(2)(C2O4)(4)(H2O])(N)CENTER-DOT-NH(2)O, [MNCR2(BIPY)(2)(MU-C2O4)(4)](N), AND PY)(2)(MU-C2O4)(2)(C2O4)(2)(H2O)(2)]CENTER-DOT-H2O

The self-assembly of the building blocks [Cr(bipy)(C2O4)(2)](-) with b ivalent metal ions (Ba(II), Mn(II), and Co(II)) led to three completel y different structures: [BaCr2(bipy)(2)(C2O4)(4)(H2O)](n) . nH(2)O (1) , [MnCr2(bipy)(2)(mu-C2O4)(4)](n) (2), and CoCr2(bipy)(2)(mu-C2O4)(2)( C2O4)(2)(H2O)(2) . H2O (3). The molecular and crystal structures of th e three compounds were determined. Crystal 1 is monoclinic, P2(1)/n, w ith a = 15.949(11) Angstrom, b = 13.206(9) Angstrom, c = 16.957(12) An gstrom, beta = 113.39(4)degrees, and Z = 4. The compound is a scaffold ing-like material with a unique three-dimensional structure. Crystal 2 is monoclinic, P2(1)/c, with a = 8.674(4) Angstrom, b = 13.416(8) Ang strom, c = 27.82(2) Angstrom, beta = 107.30(4)degrees, and Z = 4. Its structure reveals a novel heterobimetallic chain with octacoordinated manganese(II) atoms. The geometry of the manganese atoms is described as a flattened square antiprism. The Co compound (3) is monoclinic, C2 /c, with a = 20.505(5) Angstrom, b = 11.093(3) Angstrom, c = 17.346(4) Angstrom, beta = 125.02(2)degrees, and Z = 4. Its structure consists of discrete linear {CrCoCr} trinuclear species with the cobalt atom ly ing on an inversion center. The [Cr(bipy)(C2O4)(2)](-) units retain th eir original environment and accomplish different coordination functio ns, acting as terminal and/or bridging ligands. The synthetic approach , namely the reaction of an aqueous suspension of the barium derivativ e, 1, with a transition metal sulfate, seems to have a wide applicabil ity in designing new heterobimetallic systems.