Aliphatic pincer-type POCOP ligands and their complexation behaviour with iridium: Crystal structure of an iridium(III) phosphinite complex

Reaction of 2 equivalents of 1,3-bis-(di-tert-butylphosphinito)-2-methyl-propane (1a) with [Ir(COD)Cl](2) affords the first aliphatic diphosphinite PCP pincer complex with iridium, Ir(H){(t-Bu2POCH2)(2)C(Me)}Cl (2). The poor yield of 2 is partly explained by the formation of a di-nuclear byproduct [IrCl(COD)](2)(mu(2)-{(t-Bu2POCH2)(2)CH(Me)}) (3). Reaction of 1,3-bis-(di-iso-propylphosphinito)-2-methyl-propane (1b) under the same condition does not give any cyclometallation, and reaction with IrCl3 center dot H2O in DMF leads to complete decomposition of the pincer ligand under the formation of Ir(H)(i-Pr2P(OH))(3)(CO) (4), underpinning the comparatively low thermal stability of aliphatic phosphinite pincer systems. (C) 2011 Elsevier B.V. All rights reserved. (Less)