Abstract：
Two Mo(0) phosphenium complexes containing ancillary secondary phosphine ligands have been investigated with respect to their ability to participate in electrophilic addition at unsaturated substrates and subsequent P-H hydride transfer to \"quench\" the resulting carbocations. These studies provide stoichiometric \"proof of concept\" for a proposed new metal-catalyzed electrophilic hydrophosphination mechanism. The more strongly Lewis acidic phosphenium complex, [Mo(CO)4(PR2H)(PR2)]+ (R=Ph, Tolp), cleanly hydrophosphinates 1,1-diphenylethylene, benzophenone, and ethylene, while other substrates react rapidly to give products resulting from competing electrophilic processes. A less Lewis acidic complex, [Mo(CO)3(PR2H)2(PR2)]+, generally reacts more slowly but participates in clean hydrophosphination of a wider range of unsaturated substrates, including styrene, indene, 1-hexene, and cyclohexanone, in addition to 1,1-diphenylethylene, benzophenone, and ethylene. Mechanistic studies are described, including stoichiometric control reactions and computational and kinetic analyses, which probe whether the observed P-H addition actually does occur by the proposed electrophilic mechanism, and whether hydridic P-H transfer in this system is intra- or intermolecular. Preliminary reactivity studies indicate challenges that must be addressed to exploit these promising results in catalysis.
摘要：
已经研究了两种包含辅助次级膦配体的Mo（0）磷络合物在不饱和底物上参与亲电子加成以及随后的P-H氢化物转移以“淬灭”所得碳阳离子的能力。这些研究为提出的新金属催化的亲电氢磷化机理提供了化学计量的“概念证明”。更强烈的路易斯酸磷络合物，[Mo(CO)4(PR2H)(PR2)]+(R=Ph,Trop),清洁氢膦酸盐1,1-二苯基乙烯，二苯甲酮,和乙烯，而其他底物反应迅速，产生由竞争性亲电子过程产生的产物。Lewis酸性较低的络合物,[Mo(CO)3(PR2H)2(PR2)]+,通常反应较慢，但参与更广泛的不饱和底物的清洁氢磷化反应，包括苯乙烯,茚,1-己烯,和环己酮,除了1,1-二苯基乙烯，二苯甲酮,和乙烯。描述了机理研究，包括化学计量控制反应以及计算和动力学分析，它通过提出的亲电子机制来探测观察到的P-H添加是否确实发生，以及该系统中的氢P-H转移是分子内还是分子间。初步的反应性研究表明，必须解决的挑战，以利用这些有希望的结果在催化。
