Tridentate phosphine ligands with novel linker-units

Abstract

The synthesis of two novel types of tripodal phosphine ligands containing vinyl and alkynyl linker functions in their ligand backbones are reported. Using pentaerythritol (1) as the starting material the functionalized phosphines H₂CCH–CH₂OCH₂C(CH₂PPh₂)₃ (6), Me₃SiCC–CH₂OCH₂C(CH₂PPh₂)₃ (10) and HCC–CH₂OCH₂C(CH₂PPh₂)₃ (11) were obtained in good yield in 4–5-step syntheses. H₂CCH–CH₂OCH₂C(CH₂PPh₂)₃ (6) and the silyl protected alkinyl derivative (CH₃)₃Si–CC–CH₂OCH₂C(CH₂PPh₂)₃ (10) were reacted with one molar equivalent of [Mo(CO)₃(MeCN)₃] to yield the yellow-brown, air stable triphosphine–molybdenum complexes [{H₂CCH–CH₂OCH₂C(CH₂PPh₂)₃}Mo(CO)₃] (12) and [{(CH₃)₃Si–CC–CH₂OCH₂C(CH₂PPh₂)₃}Mo(CO)₃] (13) the latter of which was characterized by X-ray diffraction.