PREPARATION AND STRUCTURAL CHARACTERIZATION OF [(ETA-5-C5H5)2ZR(SC6H5)]2O - QUALITATIVE DESCRIPTION OF THE BONDING IN OXO-BRIDGED DICYCLOPENTADIENYL-TRANSITION METAL DIMERS

The hydrolysis of (η5-C5H5)2Zr(SC6H5)2 was shown previously by IR spectroscopy to produce an oxo-bridged complex. The molecular structure of this material has been determined by X-ray diffraction methods and consists of two (η2-C5H5)2Zr(SC6H5) units linked by an oxo bridge. The ZrOZr bond is nonlinear at 165.8(2)° with a Zr⋯Zr interatomic separation of 3.902(1)Å. The two independent SZrO bond angles of 98.7(1) and 103.3(1)° are consistent with a d° electronic structure for each zirconium atom. The relatively short ZrO distances of 1.968(3) and 1.964(3) Å support the presence of partial double-bond character arising from the donation of electron density from filled pπ-orbitals on the oxygen atom to unfilled d-orbitals on the electron deficient d0 metal atoms. This bonding feature requires based upon orbital symmetry arguments that the (ML)2O molecular core in [(η5-C5H5)2ML]2O complexes must be nonplanar with a dihedral angle between the two LMO planes less than 90°. For [(η5-C5H5)2Zr(SC6H5)]2O, dihedral angle of 61.7° was observed. The compound crystallizes in an orthorhombic space group, Pbca, with refined lattices parameters a 16.458(4), b 20.281(5), and c 17.016(4) Å. Full-matrix least-squares refinement of 2613 diffractometry data I > σ(I) led to a final discrepancy index R(F02) = 0.044. © 1979.