Reactions of perfluoroalkyl-substituted phosphines with osmium carbonyl clusters: crystal structures of bridged, linked and substituted derivatives

Abstract

The secondary phosphine (CF₃)₂C(OH)PH(CF₃) has been shown from ¹H and ¹⁹F NMR and single-crystal X-ray diffraction studies to undergo P–C bond cleavage upon reaction with [Os₃(CO)₁₁(MeCN)] to afford the phosphido-bridged cluster [Os₃(µ-H)(CO)₁₀{µ-PH(CF₃)}]1 and the linked cluster [{Os₃(µ-H)(CO)₁₁}{µ-PH(CF₃)}{Os₃(CO)₁₁}]2. However, its reaction with [Os₃(CO)₁₀(MeCN)₂] afforded the novel molecule [Os₃(µ-H)(CO)₉{µ-HNC(Me)P(CF₃)}]3 the molecular structure of which has also been established. Compound 1 was also obtained from the reaction of (CF₃)₂C(OH)PH(CF₃) or PH(CF₃)₂ with the anionic cluster [Os₃H(CO)₁₁]^–. Furthermore the primary phosphines (CF₃)₂C(OH)PH₂ and PH₂(CF₃) display similar P–C bond cleavage upon reactions with [Os₃H(CO)₁₁]^– to afford the phosphido-bridged cluster [Os₃(µ-H)(CO)₁₀(µ-PH₂)]. On the other hand, (CF₃)₂C(OH)PH₂ gave simple substitution products upon reactions with [Os₃(CO)₁₀(MeCN)₂] and [Os₃(CO)₁₁(MeCN)], as has been found for the tertiary phosphine P(CF₃)₃. Compound 2 represents the first example of two triosmium triangles linked by a terminally co-ordinated PR₂ group.