REACTIONS OF THE ETA-2-ISOMERS AND ETA-4-ISOMERS OF CP-STAR-IR(2,5-DIMETHYLTHIOPHENE) WITH PHOSPHINES, CO AND H2

The iridathiabenzene complex, Cp*Ir(η2-2,5-Me2T) (2), which may be formulated with a 16e- iridium centre, reacts with 2e- donor ligands (L = PMe3, PMe2Ph, PMePh2, PPh3, P(OPh)3, and CO) to give adducts 3-8; the structures of two of these {A figure is presented} derivatives were determined by X-ray crystallography, and the bonding in their six-membered ring is contrasted with that in 2. The η4-thiophene complex Cp*Ir(η4-2,5-Me2T) (1) also reacts with L to give the same adducts, 3-8; this reaction presumably involves 2 as an intermediate. Both 2 and 1 also undergo oxidative-addition with H2 to give Cp*Ir(η2-2,5-Me2T)(H)2 (9) which exists as the dihydride as determined by T1 measurements. © 1990.