Synthesis, reactions and catalytic activities of iridium complexes intercalated into montmorillonite

Abstract

Reactions of cationic iridium(I) complexes, [Ir(cod)(PPh₃)₂]ClO₄1 and [Ir(cod)(PPh₃)(PhCN)]ClO₄2(cod = cycloocta-1,5-diene) with water-swelled sodium montmorillonite have been shown to produce iridium complex-intercalated clays, [Ir(cod)(PPh₃)₂]⁺–montmorillonite 1c and [Ir(cod)(PPh₃)-(PhCN)]⁺–montmorillonite 2c. Compounds 1c and 2c react with CO to produce [Ir(CO)_x(PPh₃)₂]⁺(from 1c) and [Ir(CO)_y(PPh₃)]⁺(from 2c) intercalated clays. Reactions of 1c and 2c with H₂ produce cyclooctane and unknown iridium complexes remaining in the layers of the clay. While both the catalytic hydrogenation and isomerization (double-bond migration and cis–trans conversion) of olefins with 1 and 2 are in general retarded by intercalation of the catalysts, isomerization is relatively more suppressed than hydrogenation. Selective hydrogenation of the vinyl group of 4-vinylcyclohexene was found to be somewhat higher with 1c than with 1.