Solution Dynamics and Crystal Structure of CpMoOs3(CO)10(￥ì-H)2[￥ì3-￥?2-C(O)CH2Tol]

摘要

The tetranuclear heterometallic complex CpMoOs3(CO)10(レ-H)2[レ3-ョ2-C(O)CH2Tol] (1, Cp = ョ5-C5H5, Tol = p-C6H4Me) has been examined by variable-temperature 13C-NMR spectroscopy and by a full three-dimensional X-ray structual analysis. Complex 1 crystallizes in the orthorhombic space group Pna21 with a = 12.960(1) ∈, b = 11.255(l) ∈, c = 38.569(10)∈, V = 5626(2) ∈3 and ヱ(calcd) = 2.71 gcm-3 for Z = 8 and molecular weight 1146.9. Diffraction data were collectedon a CAD4 diffractometer, and the structure was refined to RF = 9.7% and RWF = 9.9% for 2530 data (MoKメ radiation). There are two essentially equivalent molecules in the crystallographic asymmetric unit. The tetranuclear molecule contains a triangulated rhomboidal arrangement of metal atoms with Os(2) and Mo at the two bridgehead positions. The metal framework is planar; the dihedral angle between Os(l)-Os(2)-Mo and Os(3)-Os(2)-Mo planes is 180∑. A triply bridging (レ3, ョ2) acyl ligand lies above the Os(l)-Os(2)-Mo plane; the oxygen atom spans the two bridgehead positions, while the carbon atom spans one bridgehead position and an acute apical position. The molecular architecture is completed by an ョ5-cyclopentadienyl ligand and a semi-triply bridging carbonyl ligand on the molybdenum atom, and nine terminal carbonyl ligands-four on Os(3), three on Os(l), and two on Os(2). The two hydride ligands are inferred to occupy the Os(l)-Os(2) and Mo-Os(3) edges from structural and NMR data.