Synthesis, reactivity and catalytic activity in transfer hydrogenation of ketones of ruthenium(II) and ruthenium(IV) complexes containing the novel N-thiophosphorylated iminophosphorane-phosphine ligands Ph_2PCH_2P{=NP(=S)(OR)_2}Ph_2 (R = Et, Ph)

摘要

Iminophosphorane-phosphines Ph_2PCH_2P{=NP(=S)(OR)_2}Ph_2 (R = Et 1a, Ph 1b) have been prepared by treatment of bis(diphenylphosphino)methane with an equimolar amount of thiophosphorylated azides (RO)_2P(=S)N_3. Dimers [{Ru(η~6-p-cymene)(μ-Cl)Cl}_2] and [{Ru(~3:η~3-C_(10)H_(16))(μ-Cl)Cl}_2] react with a two-fold excess of 1a,b yielding the neutral complexes [Ru(η~6-p-cymene)Cl_2(k~1-P-Ph_2PCH_2P{=NP(=S)(OR)_2}Ph_2)] (R = Et 2a, Ph 2b) and [Ru(η~3:η~3-C_(10)H_(16))Cl_2(k~1-P-Ph_2PCH_2P{=NP(=S)(OR)_2}Ph_2)] (R = Et 5a, Ph 5b), respectively. Treatment of 2a, b and 5a, b with one equivalent of AgSbF_6 affords the cationic species [Ru(η~6-p-cymene)Cl(k~2-P,S-Ph_2PCH_2P{=NP(=S)(OR)_2}Ph_2)][SbF_6] (R = Et, 6a, Ph 6b), respectively. The structure of the cation of complex 6a has been confirmed by X-ray crystallography. The preference observed for the k~2-P,S-vs. k~2-P,N-coordination of 1a,b seems to be sterically controlled since theoretical calculations on the models [Ru(η~6-C_6H_6)Cl(k~2-P,N-H_2PCH_2P{=NP(=S)(OH)_2}H_2)~+ A and [Ru(η~^-C_6H_6)Cl(k~2-P,S-H_2PCH_2P{=NP(=S)(OH)_2}H_2)]~+ B show that isomer A is ca. 5.0 kcal mol~(-1) more stable than B. Dicationic complexes [Ru(η~6-p-cymene)(K~3-P,N,S-Ph_2PCH_2P{=NP(=S)(OR)_2}Ph_2}][SbF_6]_2 (R = Et 4a, Ph 4b) and [Ru(η~3:η~3-C_(10)H_(16))(k~3-P,N,S-Ph_2PCH_2P{=NP(=S)(OR)_2}Ph_2)][SbF_6]_2 (R = Et 7a, Ph 7b) have been obtained by treating 2a, b and 5a, b, respectively, with two equivalents of AgSbF_6. The reactivity of [Ru(η~6-p-cymene)(k~3-P,N,S-Ph_2PCH_2P{=NP(=S)(OEt)_2}Ph_2)][SbF_6]_2 4a towards neutral and anionic ligands has been explored allowing the synthesis of complexes [Ru(η~6-p-cymene)(L)(k~2-P,S-Ph_2PCH_2P{=NP(=S)(OEt)_2}Ph_2)][SbF_6]_2 (L=N=CMe 8, PMe_3 9, PMe_2Ph 10, PMePh_2 11) and [Ru(η~6-p-cymene)X(k~2-P,S-Ph_2PCH_2P{=NP(=S)(OEt)_2}Ph_2)][SbF_6] (X = Br 12, I 13, N_3 14), respectively. The catalytic activity of complexes 2-7a,b in transfer hydrogenation of ketones by propan-2-ol has been also studied.