First Diphosphinoamine Ligand Bearing a Polymerizable Side Chain: Complexation with Copper(I) RITU AHUJA, ASHOKA G. SAMUELSON Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 560012, India ABSTRACT: A diphosphinoamine ligand with a polymerizable side chain, (PPh 2 ) 2 N CH 2 C 6 H 4 CH¼¼CH 2 (vbzpnp or 1), was synthesized. The ligand could be polymer- ized by anionic polymerization with n-butyllithium as the initiator. Polyvbzpnp was soluble in tetrahydrofuran and chloroform but was insoluble in methanol and was characterized with NMR, IR, and gel permeation chromatography. The number- average and weight-average molecular weights were 40,050 and 55,690, respectively, and the polydispersity index was 1.39. [Cu(CH 3 CN) 4 ]ClO 4 formed a bischelated com- plex with the monomer and produced [Cu(1) 2 ]ClO 4 (2), and CuCl formed a tetramer, Cu 4 (1) 2 Cl 4 (3). All the compounds (1, 2, and 3) were characterized with single-crystal- structure determination, NMR, and IR spectroscopy. The addition of [Cu(CH 3 CN) 4 ]- ClO 4 to polyvbzpnp resulted in an insoluble crosslinked polymer, which was charac- terized with solid-state 31 P{ 1 H} magic-angle-spinning NMR. The copolymerization of styrene and 1 produced a styrene–vbzpnp copolymer that was found to be soluble in common organic solvents. Keywords: anionic polymerization; copper(I); crosslinking; diphosphinoamine; gel permeation chromatography (GPC) INTRODUCTION The immobilization of homogeneous catalysts on a support is one of the possible ways of prepar- ing analogous, well-defined heterogeneous cata- lytic systems. The development of insoluble-pol- ymer-bound metal catalysts and reagents that maintain high activity and selectivity has attracted immense interest. 1–3 In an ideal case, these insoluble supported complexes can be recovered by simple filtration and recycled. There are, however, a number of disadvantages, including metal leaching during the course of the reaction, that lead to nonrecyclability. Another strategy that has been gaining atten- tion is the use of soluble polymeric supports instead of their insoluble counterparts. In prac- tice, the separations are achieved with several methods. The easiest process is dilution with an appropriate solvent that induces precipitation and crystallization. 4,5 Other techniques, such as dialysis through semipermeable membranes, 6 centrifugation methods, gel permeation chroma- tography (GPC), 7 and adsorption chromatogra- phy, 8,9 have also been demonstrated. The number and diversity of transition-metal phosphine complexes are very large, and a wide range of catalysts is available for synthetic organic transformations. Therefore, it comes as little surprise that the preparation of polymer- This article includes Supplementary Material available from the authors upon request or via the Internet at http:// www.interscience.wiley.com/jpages/0887-624X/suppmat. Correspondence to: A. G. Samuelson (E-mail: ashoka@ ipc.iisc.ernet.in)