Novel chiral 1,5-diaza-3,7-diphosphacyclooctane ligands and their transition metal complexes

Reaction of bis(hydroxymethyl)phenylphosphine with (R)- or (S)-(alpha)-methylbenzylamine leads to the novel cyclic chiral bisphosphine ligands 1,5-(R,R)- and 1,5-(S,S)-bis((alpha)-methylbenzyl)-3,7-diphenyl-1,5-diaza-3,7-diphosphacyclooctane (1r or 1s). Novel chiral chelate complexes of PtII(2r, 3r and 3s), PdII(4s, 5s) and ReI(6r) have been obtained by reaction of 1r or 1s with [MCl2(cod)](M = Pt, Pd; cod = 1,5-cyclooctadiene) and [{ReBr(CO)3(thf)}2]. Compounds 1-6 were characterised by multinuclear NMR (1H, 13C, 31P) and IR spectroscopy. The former technique revealed the presence of two inequivalent phosphorus atoms in 6r. The molecular structure of 1r confirmed the absolute configuration of the chiral centers and a chair-chair conformation of the heterocycle with equatorial orientation of the substituents on phosphorus and axial on nitrogen atoms. Compound 1s was used to form a palladium catalyst for the copolymerisation of carbon monoxide and norbornadiene. The structures of the co-polymers obtained were characterised by GPC, 1H and 13C NMR spectroscopy and elemental analysis.