COORDINATION GEOMETRIES IN BIS(DI-2-PYRIDYLAMINE)COPPER(II) COMPLEXES - CRYSTAL-STRUCTURES OF [CUL(2)](PF6)(2), [CUL(2)(NO3)(2)] AND [CUL(2)(NCS)(1.5)(CLO4)(0.5)] [CUL(2)(NCS)](2)(CLO4)(2) L=DI-2-PYRIDYLAMINE)

The crystal structures of three compounds containing bis(di-2-pyridylamine)-copper(II) complex units have been determined by X-ray crystallographic methods; [Cu(dpa)(2)](PF6)(2) (1), [Cu(dpa)(2)(NO3)(2)] (2) and [Cu(dpa)(2)(NCS)(1.5)-(ClO4)(0.5)][Cu(dpa)(2)(NCS)](2)(ClO4)(2) (3). Compound 1 crystallizes in space group Fddd with cell dimensions a=9.418(2), b=13.472(3), c=40.834(5) Angstrom; compound 2 in space group P2(1)/c with a=8.413(2), b=17.096(2), c=7.603(1) Angstrom, beta=94.18(1)degrees; compound 3 in space group P2(1)/c with cell dimensions a=12.758(1), b=14.459(2), c=19.397(3) Angstrom, beta=93.81(1)degrees. The structures were refined by full-matrix least-squares methods to R-values of 0.049, 0.031 and 0.060 for compounds 1, 2 and 3, respectively, using 1110, 1631 and 4760 reflections collected at room temperature with monochromated MoK alpha radiation. In compound 1 the anions are uncoordinated, and the complex features the compressed tetrahedral geometry. In compound 2 the complex unit is centrosymmetric and octahedrally elongated, with the anions coordinating in axial positions. Two crystallographically independent molecules are found in compound 3, one complex unit being centrosymmetric and octahedrally elongated, the other close to square-based pyramidal with one of the dipyridylamine ligands occupying the apical and one of the equatorial positions.