Metallacyclohexasulfanes: the crystal and molecular structures of (η5-C5H5)2MS5, M = Zr and Hf
The crystal and molecular structures of (η5-C5H5)2ZrS5, 2, and (η5-C5H5)HfS5, 3, have been determined by single crystal diffractometry methods. Both compounds crystallized with four molecules in a monoclinic unit cell of dimensions: a = 8.984(3) Å, b = 13.336(4) Å, c = 11.421(2), β = 93.10(2)° for 2, and a = 9.012(2) Å, b = 13.291(2) Å, c = 11.381(2) Å, β = 93.25(1)° for 3; the space group is P21/n for both. These crystals of 2 and 3 are thus isomorphous with those of (C5H5)2TiS5, 1, studied by Epstein etal. (3a). The structures of all three complexes are very similar consisting of a cyclohexane-like six-membered MS5 ring with two C5H5 rings attached to the metals in an axial and equatorial position. The coordination spheres of 2 and 3 are less crowded than that of 1. The consequences of this are discussed with respect to the barriers to ring inversion in these complexes.