Synthesis and coordination chemistry of ortho-perfluoroalkyl-derivatised triarylphosphines

Abstract

In order to establish the steric and electronic effects of fluorous ponytails in the ortho-positions of triarylphosphines the two novel phosphines, PPh₂(2-C₆H₄C₆F₁₃) II and P(4-C₆H₄C₆F₁₃)₂(2-C₆H₄C₆F₁₃) V, have been synthesised and their coordination chemistry investigated and compared with that of the ortho-trifluoromethyl-derivatised ligand, PPh₂(2-C₆H₄CF₃) VI. The single crystal X-ray structures of Ph₂P(O)(2-C₆H₄C₆F₁₃) and Ph₂P(O)(2-C₆H₄CF₃), along with that of PPh₂(2-C₆H₄CF₃), are reported and compared with each other. The large steric influence of the ortho-trifluoromethyl and -perfluorohexyl substituents results in the formation of the, normally, less-thermodynamically favoured trans-[PtCl₂L₂] complexes. Analysis of the single crystal X-ray structures of trans-[PtCl₂{PPh₂(2-C₆H₄CF₃)}₂] 1, trans-[PtCl₂{PPh₂(2-C₆H₄C₆F₁₃)}₂] 2 and trans-[RhCl(CO){PPh₂(2-C₆H₄CF₃)}₂] 4 reveals a larger cone angle for PPh₂(2-C₆H₄CF₃) (169°) than for PPh₂(2-C₆H₄C₆F₁₃). An average cone angle of 166° was calculated for the latter phosphine with values ranging from 164 to 168°.