Phosphagermylenylidenes (R–P═Ge), as heavier analogs of isonitriles, whether in their free state or as complexes with a Lewis base, have not been previously identified as isolable entities. In this study, we report the synthesis of a stable monomeric phosphagermylenylidene within the coordination sphere of a Lewis base under ambient conditions. This species was synthesized by Lewis base-induced dedimerization of a cyclic phosphagermylenylidene dimer or via Me₃SiCl elimination from a phosphinochlorogermylene framework. The deliberate integration of a bulky, electropositive N-heterocyclic boryl group at the phosphorus site, combined with coordination stabilization by a cyclic (alkyl)(amino)carbene at the low-valent germanium site, effectively mitigated its natural tendency toward oligomerization. Structural analyses and theoretical calculations have demonstrated that this unprecedented species features a P═Ge double bond, characterized by conventional electron-sharing π and σ bonds, complemented by lone pairs at both the phosphorus and germanium atoms. Preliminary reactivity studies show that this base-stabilized phosphagermylenylidene demonstrates facile release of ligands at the Ge atom, coordination to silver through the lone pair on P, and versatile reactivity including both (cyclo)addition and cleavage of the P═Ge double bond.

中文翻译：

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卡宾稳定的磷酰亚甲基：异腈的较重类似物


Phosphagermylenylidenes (R–P=Ge) 作为异腈的较重类似物，无论是游离状态还是与路易斯碱的复合物，之前尚未被鉴定为可分离的实体。在这项研究中，我们报告了在环境条件下在路易斯碱的配位范围内合成稳定的单体磷酸二亚甲基。该物质是通过路易斯碱诱导的环状磷酸二甲亚甲基二聚体的去二聚作用或通过从膦基氯甲亚甲基骨架中消除 Me ₃ SiCl 来合成的。在磷位点有意整合一个大的、带正电性的N-杂环硼基，结合低价位锗位点的环状（烷基）（氨基）卡宾的配位稳定，有效地减轻了其低聚的自然趋势。结构分析和理论计算表明，这种前所未有的物质具有 P=Ge 双键，其特征是传统的电子共享 π 和 σ 键，并在磷和锗原子上均由孤对电子互补。初步反应性研究表明，这种碱稳定的磷亚二亚烯表现出在 Ge 原子处轻松释放配体，通过 P 上的孤对电子与银配位，以及多功能反应性，包括 P=Ge 双键的（环）加成和裂解。