The Adarnantane Structure in Polynuclear cu,&, Cores : The Crystal and Molecular Structures of cud[ sc(NH2)2]6(N03)4*4H20 and Cu4[sc(NH2)2],(NO3)4'4H2O

The crystal structures of tris(ethy1enethiourea)copper (I) sulphate and tris(tetramethy1thiourea) copper-(I) tetrafluoroborate have been determined and both shown to contain CuQ) and three sulphur atoms in a planar arrangement.THE stereochemistry of copper( 1) is important not only because of its chemical interest, but also because of its relevance to oxidation-reduction in copper-containing en2ymes.l With soft ligands, e.g., sulphur, compounds with the same stoicheiometry may have different stereochemistry. Tris(thiourea) copper (I) tetrafluoroborate, [Cu-(tu),]BF,,, and tris-(NN'-dimethylthiourea)copper(I) tetrafluoroborate, [Cu(~-dmtu),]BF,,~ are sulphur-bridged dimers with tetrahedral CuI ; while tris(ethy1enethiourea)copper(1) sulphate and tris(tetramethylthiourea)copper(I) tetrafluoroborate are trigonal planar CuI monomers. Hence, the stereochemistry of CuI with "soft" atom donors is very flexible. We report here the crystal and molecular structure of the last two complexes.

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The structure of bis(triphenylphosphine)-diborane(4), B2H4-2P(C6H5)3, has been determined from X-ray diffraction data obtained from a single crystal by counter methods. The unit cell is triclinic, with a = 9.119 (2) A, b = 9.360 (2) A, c = 11.201 (2) A, = 77.574 (8)°, ß = 109.831 (8)°, and y = 119.202 (8)°. The space group is PI with one molecule per unit cell. Manual diffractometer methods (Mo radiation, y 0.71069 A) were used to obtain 798 reflections at 23°. Full-matrix least-squares refinement of the structure with anisotropic thermal parameters for all atoms except hydrogen gave a final conventional R index of 7.2%. As required by the space group symmetry, the molecule is centrosymmetric and consists of two triphenylphosphine groups attached to a B2H4 moiety. The central B2H4P2 part of the molecule has an ethane-like structure in the anti conformation. The B-B and P-B distances are 1.76 (2) and 1.935 (9) A, respectively, while the average P-C and C-C lengths are 1.83 (1) and 1.38 (1) A. The P-B bond is longer than in the isostructural, but less stable, bis-(trifluorophosphine)-diborane(4).