151925-35-8Relevant academic research and scientific papers
Complexes of functional phosphines. 23. PPh3 and β-ketophosphine complexes of cobalt(II). Crystal and molecular structures of CoCl2[Ph2PCH2C(O)Ph]2 and Co2(CO)6[Ph2PCH2C(O)Ph]2 and of the trinuclear, mixed-metal complex [(Ph3P)2 ...
Braunstein, Pierre,Kelly, David G.,Dusausoy, Yves,Bayeul, Daniel,Lanfranchi, Maurizio,Tiripicchio, Antonio
, p. 233 - 242 (2008/10/08)
Full title: Complexes of functional phosphines. 23. PPh3 and β-ketophosphine complexes of cobalt(II). Crystal and molecular structures of CoCl2[Ph2PCH2C(O)Ph]2 and Co2(CO)6[Ph2PCH2C(O)Ph]2 and of the trinuclear, mixed-metal complex [(Ph3P)2Ag(μ-Cl)2Co(μ-Cl) 2Ag(PPh3)2]·0.5OEt2. The solution chemistry of cobalt(II) ketophosphine complexes CoX2[Ph2PCH2C(O)Ph]2 (1a, X = Cl; 1b, X = Br; 1c, X = I) has been examined and compared to that of [CoX2(PPh3)2] (2a, X = Cl; 2b, X = Br; 2c, X = I). All the complexes undergo a tetrahedral-octahedral equilibrium in methanol. This is facilitated by solvent coordination rather than by the ligand's keto functions. Some degree of ligand displacement also occurs. The crystal structure of 1a has been elucidated, showing a pseudotetrahedral cobalt(II) geometry. A long interligand hydrogen-bond, not present in powder samples, is observed between the methylene group of a Ph2PCH2C(O)Ph ligand and the ketone function of the other Ph2PCH2C(O)Ph ligand. 1a reacts with Na[Co(CO)4] to afford the crystallographically characterized, metal-metal bonded centrosymmetric complex Co2(CO)6[Ph2PCH2C(O)Ph]2 (5) (Co-Co = 2.666(1) A?). The reactivity of 1a with AgBF4 and TlPF6 has also been examined and compared to that of 2a where the latter is reacted in the presence and absence of excess phosphine. Notable reaction products include the square planar cobalt(II) complex [Co{Ph2PCH2C(O)Ph}{Ph2PCH 2C(O)Ph}Cl]PF6 (6), which slowly transforms in solution to the octahedral complex [Co{Ph2PCH2C(O)Ph}2{Ph2PCH 2C(O)Ph}Cl]PF6 (7). Reaction with AgBF4 under similar conditions affords the silver phosphine complex Ag{Ph2PCH2C(O)Ph}2Cl (8). 2a reacts with AgBF4 to give [Ag-(PPh3)2]BF4, but additionally in the presence PPh3 gives (Ph3P)2Ag(μ-Cl)2Co(μ-Cl) 2Ag(PPh3)2 (13). The latter formulation involving a central CoCl42- core, and an almost linear Ag-Co-Ag arrangement has been confirmed by single-crystal X-ray diffraction. The solid state structures of 1a, 5, and 13·0.5OEt2 have been determined by single-crystal X-ray analysis. 1a crystallizes in the monoclinic space group P21/c with Z = 4 in a unit cell of dimensions a = 10.985(2) A?, b = 17.236(4) A?, c = 19.547(4) A?, and β = 104.87(2)°. 5 crystallizes in the triclinic space group P1 with Z = 1, a = 8.916(2) A?, b = 11.177(7) A?, c = 12.009(4) A?, α = 81.15(5)°, β = 76.39(2)°, and γ = 67.47(3)°. Complex 13·0.5OEt2, crystallizes in the monoclinic space group P21/c with Z = 8, a = 21.840(5) A?, b = 17.664(6) A?, c = 36.890(7) A?, and β = 93.14(2)°.
