Syntheses and characterization of organo-group 14 cobaloxime compounds

Reactions of cobaloxime Na[(t-BuPy)Co(DH)2] with Ph3ECl (E = Si, Ge, Sn, and Pb) were investigated. Metal-metal bonded complexes (t-BuPy)Co(DH)2EPh3 were isolated for E = Sn and Pb. (t-BuPy)Co(DH)2SnPh3.(C2H5)2O, C39H52CoN5O5Sn, crystallized in the monoclinic space group P21/c (Z = 4) with unit cell dimensions a = 11.6443(6) A, b = 15.6085(8) A, c = 22.6354(12) A, beta = 96.634(1) degrees , and V = 4086.4(4) A3 at 295(2) K. The structure resembled those of six-coordinate alkyl cobaloxime complexes and had Co-NPy and Co-Sn distances of 2.056(2) and 2.5568(3) A, respectively. (t-BuPy)Co(DH)2PbPh3, C35H42CoN5O4Pb, crystallized in the monoclinic space group P21/n (Z = 4) with unit cell dimensions a = 15.0104(7) A, b = 15.7693(8) A, c = 16.6230(8) A, beta = 114.348(1) degrees , and V = 3584.8(3) A3 at 295(2) K. The complex was nearly isostructural with the Sn analogue and had Co-NPy and Co-Pb distances of 2.049(2) and 2.6191(4) A, respectively. Coupling of the ortho phenyl protons to the spin 1/2 isotopes of Sn and of Pb was a characteristic feature of the 1H NMR spectrum. Additional, longer range couplings were observed for the Pb complex and for both complexes in the 13C NMR. Metal-metal bonded complexes were not obtained for E = Si or Ge. The products isolated in the latter case were the hydride Ph3GeH and the cobalt(II) complex (t-BuPy)Co(DH)2,C17H27CoN5O4, which crystallized in the orthorhombic space group Pbcn (Z = 8). Unit cell dimensions were a = 17.9821(11) A, b = 9.7449(6) A, c = 22.7374(15) A, and V = 3984.4(4) A3 at 295(2) K. The five-coordinate complex had Co-NPy = 2.096(2) A and was dimeric in the lattice.