Synthesis and Characterization of New Amphiphilic Phosphines and Palladium Metallosurfactants Esteve Valls, Antoni Solsona, and Joan Suades* Departament de Quı ´mica, Edifici C, Universitat Auto ` noma de Barcelona, 08193 Bellaterra, Spain Rene ´ Mathieu Laboratoire de Chimie de Coordination du CNRS, 205 route de Narbonne, 31077 Toulouse Cedex 4, France Francesc Comelles Institut d’Investigacions Quı ´miques i Ambientals de Barcelona, CSIC, Jordi Girona, 18-26, 08034 Barcelona, Spain Carmen Lo ´pez-Iglesias Serveis Cientı ´fico-Te ` cnics, Universitat de Barcelona, Unitat de Reconeixement Molecular, c/Baldiri Reixac 10-12, 08028 Barcelona, Spain Received January 29, 2002 The new water-soluble amphiphilic phosphines R-(C 6 H 4 )-(OCH 2 CH 2 ) n P(Ph)CH 2 CH 2 SO 3 - Na (R ) tert-octyl, n j) 1.4, 5.1, 11.2; R ) n-nonyl, n j) 1.6, 5.6, 11.4) and RP(Ph)CH 2 CH 2 SO 3 Na (R ) n-octyl, CH 3 (OCH 2 CH 2 ) 3 ) have been synthesized and characterized by NMR ( 1 H, 13 C, 31 P) and ES mass spectroscopy. The respective Pd(II) complexes were prepared by reaction with PdCl 2 (COD). Water solutions of ligands and Pd(II) complexes exhibit surfactant properties that have been studied by surface tension measurements. The critical micelle concentration (cmc) and the area occupied per molecule absorbed in the air/water interface were determined. These data show that the cmc’s of ligands are significantly higher than those of their respective metal complexes. This finding can be understood by considering the metal complex as a pseudo gemini surfactant. The values of area occupied per molecule in the interface show that ligands with a middle polyether chain yielded the metal complexes with the highest metal concentration in the interface. Introduction Phosphine ligands have been studied extensively, since they can form stable metal complexes and, at the same time, a wide range of functional groups can be anchored to the phosphorus atom. 1 Consequently, they are an excellent tool to obtain metal complexes with previously designed properties and they have been widely used in several fields such as water-soluble metal complexes 2 and asymmetric ligands. 3 In this context, the preparation of metallic complexes with surfactant prop- erties has been pursued. The amphiphilic ligands de- signed for this purpose usually display, in the same molecule, a long alkyl chain, a hydrophilic group, and one or more donor atoms. Hence, they can form a metallic complex with the properties of a surface-active agent. Previous studies with such metallic complexes have been performed with a heterogeneous group of metals and ligands, because the idea of a metallic surfactant can be useful in different areas. Thus, the formation of vesicles with a copper complex of an imidazole ligand surfactant has been studied 4 and copper metallomicelles, prepared from amine ligands, have been applied in micellar catalysis. 5 Metallomicellar copper complexes with polyamines also provide systems for evaluating metal complexes in an environment mimicing that of biological membranes. 6 In addition, metallomicelles prepared with pyridine derivatives have been studied as biomimetic models of metalloenzymes. 7 On the other hand, amphiphilic ruthenium complexes have been developed and studied at the air-water interface in order to form supramolecular assemblies. 8 * To whom correspondence should be addressed. Fax: + 34 935813101. E-mail: Joan.Suades@uab.es. (1) Comprehensive Coordination Chemistry; Wilkinson, G., Ed.; Pergamon: Oxford, U.K., 1987; Vol. 2, Chapter 14. (2) Aqueous-Phase Organometallic Catalysis; Cornils, B., Herrmann, W. A., Eds.; Wiley-VCH: Weinheim, Germany, 1998; Chapter 3.2. (3) (a) Kagan, H. B. In Asymmetric Synthesis; Morrison, J. D., Ed.; Academic Press: Orlando, FL, 1985; Vol. 5, Chapter 1. (b) Brunner, H.; Zettlmeier, W. Handbook of Enantioselective Catalysis with Transi- tion Metal Compounds; VCH: Weinheim, Germany, 1993; Vol. II. (4) Van Esch, J. H.; Stols, A. L. H.; Nolte, R. J. M. J. Chem. Soc., Chem. Commun. 1990, 1658. (5) (a) Menger, F. M.; Gan, L. H.; Johnson, E.; Durst, D. H. J. Am. Chem. Soc. 1987, 109, 2800. (b) Bhattacharya, S.; Snehalatha, K.; George, S. K. J. Org. Chem. 1998, 63, 27. (6) Ghirlanda, G.; Scrimin, P.; Tecilla, P.; Toffoletti, A. Langmuir 1998, 14, 1646. (7) Hampl, F.; Liska, F.; Mancin, F.; Tecilla, P.; Tonellatto, U. Langmuir 1999, 15, 405. 2473 Organometallics 2002, 21, 2473-2480 10.1021/om020067q CCC: $22.00 © 2002 American Chemical Society Publication on Web 05/16/2002