CRYSTAL AND MOLECULAR-STRUCTURES OF TRANS-DI-MU-THIOETHYLDINITROSYLBIS(PENTAHAPTOCYCLOPENTADIENYL)DIMOLYBDENUM, [(ETA-5-C5H5)MO(NO)(SC2H5)]2, AND CIS-DI-MU-THIOISOPROPYLDINITROSYLBIS(PENTAHAPTOCYCLOPENTADIENYL)DIMOLYBDENUM, [(ETA-5-C5H5)MO(NO)(SCH(CH3)2)]

Structures of the title compounds have been determined from three-dimensional X-ray analyses using diffractometer data. Crystals of trans-[(η5-C5H5)Mo(NO) (SC2H5)]2 are monoclinic, space group P21/c with Z = 2 in a unit cell of dimensions a = 7.924(1), b = 12.692(1), c = 9.510(1) Å, β = 109.06(1)°. Full matrix least squares refinement has returned a final R factor of 0.034 for 1120 reflections for which I > 3σ(I). The analysis confirms that the molecule is a dimer, with molybdenum atoms bridged by sulphur atoms. The molecule is situated about a crystallographic centre of symmetry and thus the (MoS)2 core is planar and the cyclopentadiene and nitrosyl ligands are in the trans configuration. The Mo-S distances are 2.398(2) and 2.400(2) Å; the MoMo′ distance is 2.923(1) Å. Crystals of cis-(η5-C5H5)Mo(NO) (SCH(CH3)2)]2 are orthorhombic, space group Im2a, with Z = 16 in a unit cell of dimensions a = 30.874(2), b = 14.849(3), c = 18.260(2) Å. The structure is based on a clearly defined subcell for which c′ = c 2 and Z′ = 8. The structure has been solved in terms of this subcell only, and therefore is described as the average of the two halves of the cell. Refinement was terminated with R = 0.067 for 1487 reflections having I > 3σ(I). Within the subcell there are two independent molecules, one of which has space group required diad symmetry, and the other mirror symmetry. The two molecules are nevertheless very similar in geometry. In contrast to the ethyl complex, the disposition of ligands with regard to the planar (MoS)2 core is cis. © 1979.