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) Å, b = 15.6085(8) Å, c = 22.6354(12) Å, β = 96.634(1)°, and V = 4086.4(4) Å3 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) Å, 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) Å, b = 15.7693(8) Å, c = 16.6230(8) Å, β = 114.348(1)°,
and V = 3584.8(3) Å3 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) Å, 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) Å, b = 9.7449(6) Å, c = 22.7374(15) Å, and V = 3984.4(4) Å3 at
295(2) K. The five-coordinate complex had Co−NPy = 2.096(2) Å and was dimeric in the lattice.