A phase based approach to insulated molecular wires: Diplatinum octatetraynediyl complexes bearing fluorous trialkylphosphine ligands

Abstract

Reactions of [(tetrahydrothiophene)Pt(C6F5)μ-Cl]2 and fluorous phosphines P((CH2)mRfn)3 (Rfn = (CF2)n−1CF3; m/n = a, 2/8; b, 3/8; c, 3/10) afford the chloride complexes trans-(C6F5)((Rfn(CH2)m)3P)2PtCl (8a-c, 40–74%), which upon treatment with butadiyne and CuI (cat.) in HNEt2/CF3C6H5 give trans-(C6F5)((Rfn(CH2)m)3P)2Pt(CC)2H (9a-c, 44–64%). Subsequent reactions with oxygen and CuCl/TMEDA in acetone yield the title complexes trans,trans-(C6F5)((Rfn(CH2)m)3P)2Pt(CC)4Pt(P((CH2)mRfn)3)2(C6F5) (10a-c, 35–52%). All platinum complexes exhibit CF3C6F11/toluene partition coefficients of >99:<1. The crystal structure of 8b shows that the perfluoroalkyl groups segregate into fluorous domains. It was therefore thought that the perfluoroalkyl groups in 10a-c would aggregate about the polyynediyl chain. However, these adducts could not be crystallized. Electrochemical oxidations of 10a-c give radical cations that are much less stable than trialkyl and triarylphosphine analogs.