4-methoxybenzyl), depending on the alkyl substituent on R-NCO. Interestingly, these reactions afford cyclic trimers as catalytic products when two equivalents or excess amounts of benzyl isocyanate are used. In contrast, reactions of [Pt(olefin)(PR3)2] with two equivalents of an alkyl or aryl isocyanate afford only the five-membered platinacycle, namely cis-[Pt–N(R)C(O)N(R)C(O)–}(PMe3)2] (R = 3-methylbenzyl
[Pd(烯烃)(PR 3)2 ](PR 3 = PMe 3,PMe 2 Ph)与两当量的芳基或异
氰酸烷基酯的反应提供顺式-[Pd –N(R)C(O)N (R)C(O)–}(PR 3)2 ](R = 1-
萘基,4-苯氧基苯基),它们是带有二聚
异氰酸酯单元的五元帕拉达环,或作为四个五元帕拉达环的组装体的环状四聚体, [Pd C(O)N(R')C(O)N(R')}(PMe 3)] 4,(R'= 3-甲基苄基,4-甲基苄基或4-甲氧基苄基),取决于R-NCO上的烷基取代基。有趣的是,当使用两个当量或过量的
异氰酸苄酯时,这些反应提供环状三聚体作为催化产物。相比之下,[Pt(烯烃)(PR 3)2 ]与两当量的烷基或芳基
异氰酸酯的反应仅提供五元
铂盐环,即顺式-[Pt –N(R)C(O)N( R)C(O)–}(PMe 3)2 ](R = 3-甲基苄基,4-甲基苄基,4-
氟苄基,4-甲氧基苄基,(S)