Reactivity of an Unsaturated Iridium(III) Phosphoramidate Complex, [Cp*Ir{κ2-N,O}][BArF4

Abstract

The three-legged piano stool complex [Cp*Ir(κ2-N,O-Xyl(N)P(O)(OEt)2)(Cl)], [1] (Cp* = η5-C5Me5, Xyl = 2,6-dimethylphenyl), was prepared from reaction of 0.5 equiv of [Cp*IrCl2]2 with the sodiated phosphoramidate ligand Na[Xyl(N)P(O)(OEt)2]. Treatment of [1] with Na[BArF4], [BArF4] = [B(C6H3(CF3)2)4], led to the formation of the 16-electron two-legged piano stool species [Cp*Ir(κ2-N,O-Xyl(N)P(O)(OEt)2)][BArF4], [2][BArF4], which was characterized in both solution and solid state. Reactivity screening revealed that complex [2][BArF4] undergoes addition of a variety of Lewis bases to afford the corresponding 18-electron adducts with concomitant movement of the phosphoramidate ligand from κ2-N,O to κ1-N, [Cp*Ir(κ1-N-Xyl(N)P(O)(OEt)2)(L)2][BArF4]; L = CNtBu, [3][BArF4], CNXyl, [4][BArF4], MeCN, [7][BArF4], bipy, [8][BArF4]; bipy = 2,2′-bipyridine. For complex [7][BArF4], variable-temperature 31P{1H} NMR spectroscopy revealed that MeCN coordination was reversible between 238 and 190 K. To probe E–H (E = Si, B) ...