Synthesis and reactivity of the silylated triphosphites [(R1O)2PO]3SiR2(R1= Me or Et; R2= Me, Ph or CHCH2). Crystal structure of fac-[Mo(CO)3{P,P,P-[P(OMe)2O]3SiMe}]

Abstract

The silylated triphosphites [(R¹O)₂PO]₃SiR²(R¹= Me or Et; R²= Me, Ph or CHCH₂) have been prepared in high yield by the reactions between SiR²Cl₃ and (R¹O)₂P(O)H in the presence of NEt₃. The compound [(MeO)₂PO]₃SiMe reacts with [Mo(CO)₄(nbd)](nbd = norbornadiene) and [Mo(CO)₃(η⁶–C₇H₈)] to afford [Mo(CO)₄{P,P-[P(OMe)₂O]₂SiMe[OP(OMe)₂]}] and fac-[Mo(CO)₃{P,P,P-[P(OMe)₂O]₃SiMe}] respectively. The crystal structure of fac-[Mo(CO)₃{P,P,P-[P(OMe)₂O]₃SiMe}] has been determined in the space group P2₁/c with a= 10.1129(8), b= 14.3197(12) and c= 14.9906(11)Å. The metal-co-ordinated triphosphites are significantly less electron-releasing than tertiary phosphine analogues and more closely resemble the η-arenes of [Mo(CO)₃(η⁶–C₆H_6–nMe_n)] in their electronic character.