EARLY LATE HETEROBIMETALLIC COMPLEXES - SYNTHESES AND SPECTRAL AND STRUCTURAL STUDIES OF THIOLATO-BRIDGED TI/CU AND V/CU COMPLEXES

The heterobimetallic complexes [Cp2Ti(μ-SMe)2CuPCy3]PF6(1), [Cp2Ti(μ-SR)2Cu(NCMe)2]PF6(R = Me (2), R = Et (3)), and [(Cp2Ti(μ-SMe)2)2Cu]PF6(4) have been prepared and characterized. Variable-temperature NMR studies of 1 and 2 show that the preferred orientation in solution of the methyl substituents on sulfur at low temperature is one in which they adopt a cisoid disposition. Inversion at sulfur is proposed as the mechanism that leads to the time-averaged signals at ambient temperature. The energies of the fluxional processes were found to be 77 and 80 kJ/mol for 1 and 2, respectively. Complex 2 crystallizes in the triclinic space group P1, with a = 8.038 (2) Å, b = 13.169 (3) Å, c = 1 1.732 (3) Å, α = 109.31 (2)°, β = 106.12 (2)°, γ = 89.29 (2)°, Z = 2, and V = 1122 (1) Å3. The structural data are consistent with a cisoid disposition of the methyl groups on sulfur. Cyclic voltammetric studies of 1-4 show that reduction of these complexes leads to complex degradation. Electronic analogues of reduced 1 and 2 were prepared by employing V(IV). The complexes [Cp2V(μ-SEt)2CuPR3]PF6(R = Ph (5), R = Cy (6)), [Cp2V(μ-SR)2Cu(NCMe)2]PF6(R = Me (7), R = Et (8)) show EPR spectra characteristic of V(IV) complexes. For complexes 5 and 6, hyperfine coupling to Cu(I) and P is discernible. Computer simulation revealed that the coupling to Cu is 9.5 G and to P is 8.0 G. The implications of both the structural and spectroscopic parameters for these heterobimetallic complexes are discussed. The data are consistent with electronic communication between the metal centers. A dative interaction from the electron-rich d10Cu(I) center to the d° Ti(IV) center is suggested. © 1990, American Chemical Society. All rights reserved.