Coordination chemistry of new selective ethylene trimerisation ligand Ph2PN(iPr)P(Ph)NH(R) (R = iPr, Et) and tests in catalysis

Abstract

The synthesis of [Ph2PN(iPr)P(Ph)NH(R)] (R = iPr, Et) (1, 2) is described and the structure of 2 has been determined by single-crystal X-ray analysis. Compound 1 readily reacts with chromium(0), nickel(0), nickel(ii), palladium(ii), platinum(ii) and iron(ii) complexes to give four-membered rings (3-10) via P,P′ coordination. The molecular structures of [Cr(CO)4{Ph2PN( iPr)P(Ph)NH(R)-P,P′}] (R = iPr, Et) (3, 4), [Cr(CO)3(NCCH3){Ph2PN(iPr)P(Ph) NH(iPr)-P,P′}] (5), [Ni{Ph2PN(iPr)P(Ph) NH(iPr)-P,P′}2] (6), cis-[MX2{Ph 2PN(iPr)P(Ph)NH(iPr)-P,P′}] (M = Ni, Pd, Pt; X = Cl or Br) (7, 8, 9) and trans-[Fe(NCCH3)2{Ph 2PN(iPr)P(Ph)NH(iPr)-P,P′} 2](BF4)2 (10) have been determined by X-ray diffraction. In the solid state, these complexes show tight phosphine bite angles in the range 67.89(2)°to 74.97(4)°and the central nitrogen atom adopts an almost planar (sp2) geometry. Complexes 3, 5, 6, 7 and 10 are tested for their catalytic activity in ethylene oligomerisation. Additionally, complex 10 is tested in hydrogenation of olefins. © 2010 The Royal Society of Chemistry.