Dinuclear Cp*Co Amido and Alkoxo Complexes: Synthesis, Structures, and Reactivity
摘要:
New amido- and alkoxo-bridged dinuclear cobalt complexes [Cp*Co(mu-X)](2) (X = NHTol (2), NHBoc (3), OBn (4); Cp* = eta(5)-C(5)Me(5); Tol = p-tolyl; Boc = t-BuOCO; Bn = CH(2)Ph) have been prepared by the reaction of [Cp*Co(mu-Cl)](2) (1) with LiX and characterized by X-ray analysis. The amido complexes 2 and 3 are diamagnetic and feature a folded Co(2)N(2) butterfly structure with a Co-Co single bond. In contrast, the alkoxo complex 4 is paramagnetic and contains a planar Co(2)O(2) core with a long Co center dot center dot center dot Co separation. Dynamic stereochemical processes in 2 and 3 were investigated by NMR spectroscopy, and cis-trans isomerization in 2 and Co(2)N(2) ring inversion in 2 and 3 were identified. Complexes 2 and 4 reacted with carbon monoxide to give N,N'-di-p-tolylurea and dibenzyl carbonate, respectively, along with [Cp*Co(CO)(2)] and [Cp*Co(mu-CO)](2). Oxidation of 2 with iodine and ferrocenium triflate afforded the Co(III) complexes [(Cp*Co)(2)(mu-I)(mu-NHTol)(2)]I (5) and [(Cp*Co)(2)-(mu-OH(2))(mu-NHTol)(2)][OTf](2) (6), respectively, the latter being characterized by X-ray analysis.
Dinuclear Cp*Co Amido and Alkoxo Complexes: Synthesis, Structures, and Reactivity
摘要:
New amido- and alkoxo-bridged dinuclear cobalt complexes [Cp*Co(mu-X)](2) (X = NHTol (2), NHBoc (3), OBn (4); Cp* = eta(5)-C(5)Me(5); Tol = p-tolyl; Boc = t-BuOCO; Bn = CH(2)Ph) have been prepared by the reaction of [Cp*Co(mu-Cl)](2) (1) with LiX and characterized by X-ray analysis. The amido complexes 2 and 3 are diamagnetic and feature a folded Co(2)N(2) butterfly structure with a Co-Co single bond. In contrast, the alkoxo complex 4 is paramagnetic and contains a planar Co(2)O(2) core with a long Co center dot center dot center dot Co separation. Dynamic stereochemical processes in 2 and 3 were investigated by NMR spectroscopy, and cis-trans isomerization in 2 and Co(2)N(2) ring inversion in 2 and 3 were identified. Complexes 2 and 4 reacted with carbon monoxide to give N,N'-di-p-tolylurea and dibenzyl carbonate, respectively, along with [Cp*Co(CO)(2)] and [Cp*Co(mu-CO)](2). Oxidation of 2 with iodine and ferrocenium triflate afforded the Co(III) complexes [(Cp*Co)(2)(mu-I)(mu-NHTol)(2)]I (5) and [(Cp*Co)(2)-(mu-OH(2))(mu-NHTol)(2)][OTf](2) (6), respectively, the latter being characterized by X-ray analysis.