Crystal and molecular structure of tetraphenylarsonium tetranitratomanganate(II) and X-ray study of other M(NO3)42– ions (M = Ni, Cu, or Zn)
Tetraphenylarsonium tetranitratomanganate(II), (Ph4As)2Mn(NO3)4 forms monoclinic crystals, space group C2/c, with a= 23·35, b= 11·37, c= 18·36 Åβ= 107·0° and is isomorphous and nearly isostructural with the corresponding cobalt complex. The eight co-ordination polyhedron in the anion is of approximate D2d(dodecahedral) symmetry. The bidentate nitrate ions are co-ordinated to the metal in a more symmetrical fashion than in the cobalt analogue, the bonds defining the elongated bisphenoid averaging 2·27 Å(2·08) and those defining the flattened bisphenoid averaging 2·34 Å(2·45)[values for Co(NO3)42– in parentheses]. These differences apparently reflect the change in central metal-atom radius and the d-electron configuration.
Unit-cell and space-group data indicate that the Zn(NO3)42– ion is also eight co-ordinate but that the corresponding copper complex is not.