Nitriles (R–C≡N) have been investigated since the late eighteenth century and are ubiquitous encounters in organic and inorganic syntheses. In contrast, heavier nitriles, which contain the heavier analogues of carbon and nitrogen, are sparsely investigated species. Here we report the synthesis and isolation of a phosphino-silylene featuring an N-heterocyclic carbene-phosphinidene and a highly sterically demanding silyl group as substituents. Due to its unique structural motif, it can be regarded as a Lewis base-stabilized heavier nitrile. The Si–P bond displays multiple bond character and a bent R–Si–P geometry, the latter indicating fundamental differences between heavier and classical nitriles. In solution, a quantitative unusual rearrangement to a phosphasilenylidene occurs. This rearrangement is consistent with theoretical predictions of rearrangements from heavier nitriles to heavier isonitriles. Our preliminary reactivity studies revealed that both isomers exhibit highly nucleophilic silicon centres capable of oxidative addition and coordination to iron tetracarbonyl.

自 18 世纪末以来，人们一直在研究腈 (R–CeqN)，并且在有机和无机合成中普遍存在。相比之下，较重的腈含有较重的碳和氮类似物，很少被研究。在这里，我们报道了以 N-杂环卡宾次膦亚基和高空间要求的甲硅烷基作为取代基的膦基亚甲硅基的合成和分离。由于其独特的结构基序，它可以被视为路易斯碱稳定的重腈。 Si-P 键显示出多重键特性和弯曲的 R-Si-P 几何形状，后者表明较重的腈与经典的腈之间存在根本差异。在溶液中，发生定量的不寻常的重排，形成磷硅亚基。这种重排与从较重的腈到较重的异腈的重排的理论预测一致。我们的初步反应性研究表明，两种异构体均表现出高度亲核的硅中心，能够氧化加成并与四羰基铁配位。