The geometrically constrained tricyclic phosphine 3b has two annulated five-membered PC₄ heterocycles with the P atom in a bridgehead position. Treatment with (THF)M(CO)₅ (M = Cr, Mo, and W) afforded M(CO)₅ complexes 4–6, of which the Cr and Mo compounds showed in heat the unusual insertion of a carbonyl C atom into a P–C bond of one of the strained PC₄ rings. Ring expansion yielded a six-membered PC₅ heterocycle with an exocyclic C═O group and afforded new phosphine ligand 8 that contains annulated five- (1×) and six-membered (2×) rings. Its Mo complex (7) was obtained by treatment of starting phosphine 3b with excess Mo(CO)₆ in hot toluene. Phosphine 8 was removed from the metal atom by addition of the diphosphine Ph₂PC₂H₄PPh₂. Treatment of 8 with AlBr₃ resulted in enolization and an increased nucleophilicity of the β-C atom, which causes dimerization by P–C bond formation to yield a barrelane type molecule (9).

中文翻译：

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几何上受约束的三环膦：配位，通过将CO插入P–C键中而扩环和路易斯酸引发的具有P ₂ C ₂₂主链的寡环分子的形成

受几何约束的三环膦3b具有两个环状的五元PC ₄杂环，其中P原子位于桥头位置。治疗（THF）M（CO）₅（M =的Cr，Mo和W），得到M（CO）_5个络合物4 - 6，其中Cr和Mo化合物显示在热量的羰基C原子的不寻常的插入应变PC ₄环之一的P–C键。扩环产生具有环外C ＝ O基团的六元PC ₅杂环，并提供了新的膦配体8，其包含带环的五（1x ）和六元（2x）环。它的钼络合物（7）是通过用过量的Mo（CO）₆在热甲苯中处理起始膦3b来获得的。通过添加二膦Ph ₂ PC ₂ H ₄ PPh _2，从金属原子上除去了膦8。用AlBr ₃处理8会导致烯醇化和增加β-C原子的亲核性，这会导致通过P-C键形成的二聚反应产生桶形分子（9）。