Wasserlösliche Phosphane V. Komplexe amphiphiler tertiärer alkylphosphane mit Ammoniumgruppierungen in den seitenketten

Monocationic amphiphilic tertiary phosphines [RMe2N-(CH2)n-PR′2]+ X− (1–3) obtained by P-alkylation of the corresponding primary phosphines (R′  H) form stable tungstencarbonyl-, Rh(I)-olefin- and square planar Pd(II)-complexes (4–8a). Stepwise protonation of [Me2N-(CH2)2]3P (9) by Ph3P · HBr or aqueous HCl affords tricationic tertiary phosphine ligands, e.g. {[HMe2N-(CH2)2]3P}3+ 3X− (13, 13b) and the phosphonium salt {[HME2N-(CH2)2]3P-H}4+ 4Cl− (13a). The pKa-values 9.67, 8.86, 7.92 and 1.9 have been obtained by titration of 13a with NaOH in aqueous solution. Highly charged Pd(II)-complexes (16a, 16b) with extreme water solubilities were obtained from 13 and PdBr2 or by N-protonation of cis-PdCl2(9)2 with HCI. The crystal structures of 13 · 0.5H2O and {trans-{[HMe2N-(CH2)2]3P})2PdCl2}6+ 6Cl−· 2MeOH (16b) (space group C2/c) have been determined. While the P( … N)3 skeleton of the trication in 13 is almost flat, it is folded back on coordination to palladium(II) in 16b.