Crystal structure of tetraaqua(ethylenediamine)nickel(II) sulphate dihydrate and of tetraaqua(2,2'-bipyridyl)nickel(II) sulphate dihydrate

Abstract

The crystal structures of the title compounds, [Ni(OH2)4(en)] [SO4].2H2O, (1), and [Ni(OH2)4(bpy)]- [SO4].2H2O, (2), have been determined by single-crystal X-ray diffraction methods at 295 K, being refined by full matrix least-squares methods to residuals of 0.028,0.031 for 1852, 4323 independent 'observed' reflections respectively. Crystals of (1) are monoclinic, C2/c, a 9.459(4), b 12.192(7), c 12.294(3) Ŭ ߠ119.84(4)ꬠZ 4. In the cation, Ni-N is 2.061(2) Ż Ni-O (trans to O, N respectively) are 2.106(2), 2.063(2) Ů Instead of being enlarged above 90ꠡs predicted from repulsion theory, the angle between the pair of oxygen atoms trans to nitrogen is diminished, being 87 14(7)ꮠCrystals of (2) are triclinic, P1, a 11.476(5), b 9.351(5), c 7.793(4) Ŭ a 77.63(4), ߠ83.52(3), ?87.40(4)ꬠZ 2. In the cation, Ni-N are both 2.063(2) Ů Ni-O (trans to N, O respectively) are 2.060(2), 2.O42(2); 2.O80(2), 2Ů The short Ni-O distance [2.042(2)ŝ is associated with the coordination of a trigonal water molecule.