Accessing δ-B–H Coordinated Complexes of Rh(I) and Ir(I) Using Mono- and Dihydroboranes: Cooperative Stabilization by a Phosphoramidate Coligand

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• 作者：Marcus W. Drover ; Eric G. Bowes ; Jennifer A. Love ; Laurel L. Schafer
• 刊名：Organometallics
• 出版年：2017
• 出版时间：January 23, 2017
• 年：2017
• 卷：36
• 期：2
• 页码：331-341
• 全文大小：608K
• ISSN：1520-6041

文摘

Reactions of the four-membered irida(I)- and rhoda(I)heterocycles [M{κ²-N,O-Xyl(N)P(O)(OEt)₂}(η⁴-COD)] (M = Rh (1), Ir (2)) with electrophilic borane reagents are investigated. Treatment of 1 or 2 with 9-borabicyclo[3.3.1]nonane (HBC₈H₁₄) gives [M{κ²-N,H-Xyl(N)P(OH(BC₈H₁₄)(OEt)₂}(η⁴-COD)] (M = Rh (5), Ir (6)). Complexes 1 and 2 display differing reactivity toward HBMes₂ and H₂BMes: reaction with HBMes₂ provides an equilibrium mixture of [M{κ²-N,H-Xyl(N)P(OHB(Mes)₂)(OEt)₂}(η⁴-COD)] (M = Rh (7), Ir (8)) and the precursor complex 1 or 2. For H₂BMes, borane coordination was found to be irreversible and the five-coordinate bis(B–H) complexes [M{κ³-N,H,H-Xyl(N)P(OH₂BMes)(OEt)₂}(η⁴-COD)] (M = Rh (9), Ir (10)) were accessed. Complexes 9 and 10 are highly fluxional in solution; this is ascribed to rapid rotation of the 1,5-cyclooctadiene (COD) coligand. Treatment of 1 or 2 with Piers’ borane, HB(C₆F₅)₂, also provides the corresponding ring-expanded metalla(I)cycles [M{κ²-N,H-Xyl(N)P(OHB(C₆F₅)₂)(OEt)₂}(η⁴-COD)] (M = Rh (11), Ir (12)). In the absence of a stabilizing [M]··H–B interaction, treatment of 1 or 2 with B(C₆F₅)₃ provides the corresponding η⁵-iminocyclohexadienyl complexes [M{η⁵-Xyl(N)P(O··B(C₆F₅)₃)(OEt)₂}(η⁴-COD)] (M = Rh (21), Ir (22)), which result from phosphine oxide donation to the electron-deficient boron center.