Ferrocenylmethylation reactions with a phosphinoferrocene betaine

Abstract

A phosphinoferrocene betaine, N-{[1'-(diphenylphosphino)ferrocenyl]methyl}-N,N-dimethyl-3-sulfo-1-propanaminium, inner salt, Ph2PfcCH2NMe2(CH2)3SO3 (; fc = ferrocene-1,1'-diyl), was prepared by alkylation of Ph2PfcCH2NMe2 () with 1,3-propanesultone, and was studied as a ferrocenylmethylation agent. The treatment of with NaOH in hot water-dimethyl sulfoxide produced phosphinoalcohol Ph2PfcCH2OH () in a 64% yield, whereas a similar reaction with MeONa in dimethylsulfoxide-methanol furnished the corresponding ether, Ph2PfcCH2OMe (), in a 47% yield. In subsequent experiments, betaine was employed in the synthesis of phosphinoferrocene sulfones, Ph2PfcCH2SO2R, where R = Me (), Ph (), and 4-tolyl (). Compounds and some by-products of the ferrocenylmethylation reactions, namely alcohol , 1'-(diphenylphosphino)-1-methylferrocene (), and 1-{[diphenyl(2,4-cyclopentadien-1-ylidene)phosphoranyl]methyl}-1'-(diphenylphosphino)ferrocene () structurally characterised. Reactions of as the representative with ZnX2/NaX (X = Br and I) afforded unique coordination polymers [ZnNaX3()(CH3OH)]n featuring tetrahedral Zn(ii) and octahedral Na(i) centres bridged by halide ions, solvating methanol and the sulfone ligands. The reaction of with ZnBr2/KBr produced an analogous product, [ZnKBr3()(CH3OH)]n, while that with ZnBr2/LiBr furnished a different, pseudodimeric complex [Zn2Li2Br6()2(CH3OH)4(H2O)]·CH3OH, featuring tetrahedrally coordinated Zn(ii) and Li(i) centres bridged by . Reactions of with ZnBr2/MBr (M = Rb, Cs) and NaCl/ZnCl2 did not yield similar products because of an easy precipitation (low solubility) of the respective alkali metal halides.