Ring opening metathesis polymerization-derived block copolymers bearing chelating ligands: synthesis, metal immobilization and use in hydroformylation under micellar conditions

Norborn-5-ene-(N,N-dipyrid-2-yl)carbamide (M1) was copolymerized with exo, exo-[2-(3-ethoxycarbonyl-7-oxabicyclo[2.2.1]hept-5- en-2-carbonyloxy)ethyl]trimethylammonium iodide (M2) using the Schrock catalyst Mo(N-2,6-Me-2-C6H3)(CHCMe2Ph)(OCMe(CF3)(2))(2) [Mo] to yield poly(M1-b-M2). In water, poly(M1-b-M2) forms micelles with a critical micelle-forming concentration (cmc) of 2.8 x 10(-6) mol L-1; Reaction of poly(M1-b-M2) with [Rh(COD)Cl](2) (COD = cycloocta-1,5- diene) yields the Rh(I)-loaded block copolymer poly(M1-b-M2)-Rh containing 18 mg of Rh(I)/g of block copolymer with a cmc of 2.2 x 10(-6) mol L-1. The Rh-loaded polymer was used for the hydroformylation of 1-octene under micellar conditions. The data obtained were compared to those obtained with a monomeric analogue, i. e. CH3CON(Py)(2)RhCl(COD) (C1, Py = 2-pyridyl). Using the polymer-supported catalyst under micellar conditions, a significant increase in selectivity, i. e. an increase in the n: iso ratio was accomplished, which could be further enhanced by the addition of excess ligand, e. g., triphenylphosphite. Special features of the micellar catalytic set up are discussed.