Department of Chemistry, University of Toronto, 80 St George St., Toronto, Ontario, Canada M5S3H6.
Dalton Trans. 2013 Oct 7;42(37):13685-91. doi: 10.1039/c3dt51739j. Epub 2013 Aug 1.
The activation of H2 using Mes3P-AlX3 (X = Cl, Br, I) FLPs was investigated. Heating a 1 : 2 mixture of Mes3P-AlI3 under H2 afforded [Mes3PH][H(AlI3)2] 1. The alane Al(p-C6F4H)32 was prepared and a 1 : 2 solution of (otol)3P and 2 under H2 generated the salt [(otol)3PH][(μ-H)(Al(p-C6F4H)3)2] which could not be isolated. However, the bulky anion salt [Li(OEt2)][FAl(C12F9)3] was readily converted to [Et4N][FAl(C12F9)3] 3 and subsequently to the hydride salt [Et4N][HAl(C12F9)3] 4. Further reaction of 4 with [CPh3][B(C6F5)4] generated the free alane, Al(C12F9)3 which in the presence of Mes3P and exposure to H2 resulted in the formation of [Mes3PH][(μ-H)(Al(C12F9)3)2] 5. Exposing a solution of 1 in C6D5Br with ethylene, propylene or cyclohexene followed by quenching with water resulted in liberation of ethane, propane, or cyclohexane, respectively. In contrast, exposure of 5 to an atmosphere of ethylene showed no evidence of reaction. In related chemistry, protonation of [Et4N][EtAl(C6F5)3] by the phosphonium salts [R3PH][Al(C6F5)4] (R = otol (6), Mes (7), tBu (8)) and [(2,6-Cl2C6H3)3PH][AlCl4] (9) was also examined. In the case of the reaction of 6 and 9 ethane was liberated whereas with 7 and 8, no reaction occurred. The implications for transition metal-free hydrogenation catalysis are considered.
研究了 Mes3P-AlX3（X = Cl、Br、I） FLP 对 H2 的活化作用。将 Mes3P-AlI3 的 1:2 混合物加热，得到[Mes3PH][H(AlI3)2]1。制备了烷基金属 Al(p-C6F4H)32，在 H2 下，将(otol)3P 和 2 的 1:2 溶液生成了盐[(otol)3PH][(μ-H)(Al(p-C6F4H)3)2]，但不能将其分离。然而，大位阻阴离子盐[Li(OEt2)][FAl(C12F9)3]很容易转化为[Et4N][FAl(C12F9)3]3，随后转化为氢化物盐[Et4N][HAl(C12F9)3]4。进一步将 4 与[CPh3][B(C6F5)4]反应生成游离的烷基金属 Al(C12F9)3，在 Mes3P 和 H2 的存在下，生成[Mes3PH][(μ-H)(Al(C12F9)3)2]5。将 1 在 C6D5Br 中的溶液暴露于乙烯、丙烯或环己烯中，然后用去离子水猝灭，分别得到乙烷、丙烷或环己烷。相比之下，将 5 暴露于乙烯气氛中，没有观察到反应的证据。在相关化学中，[Et4N][EtAl(C6F5)3]的质子化反应由磷盐[R3PH][Al(C6F5)4]（R = otol（6）、Mes（7）、tBu（8））和[(2,6-Cl2C6H3)3PH][AlCl4]（9）进行了研究。在 6 和 9 的反应中，释放了乙烷，而在 7 和 8 的反应中，没有发生反应。考虑了对过渡金属自由氢化催化的影响。
