MODIFICATION OF THE ACID-BASE PROPERTIES OF HYDROXYCARBONYL COMPLEXES OF IRIDIUM(III) BY SUBSTITUTION OF CARBON MONOXIDE BY A TERTIARY PHOSPHINE LIGAND

Article abstract of DOI:10.1016/0022-328X(86)80043-2

A dichloromethane solution of the cationic carbonyl complex (IrCl2(CO)(PMe2Ph)3)(ClO4) reacts with aqueous KOH to give (IrCl2(CO2H)(PMe2Ph)3) which has been characterised spectroscopically.This CO2H compound is very much more basic and very much less acidic than (IrCl2(CO2H)(CO)(PMe2Ph)2).Tertiary amines will not deprotonate (IrCl2(CO2H)(PMe2Ph)3) while Li(N(SiMe3)2) leads to decarboxylation products trans, mer- and cis, mer-(IrHCl2(PMe2Ph)3).The mechanisms of these reactions are considered and the hydroxycarbonyl complex is compared with its formato isomer which decarboxylates much less readily.