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°.