RING-METHYL ACTIVATION IN PENTAMETHYLCYCLOPENTADIENYLIRIDIUM COMPLEXES .2. SYNTHESIS OF C5ME4(FUNCTIONALIZED ALKYL) COMPLEXES AND CRYSTAL-STRUCTURES OF [(C5ME4CH2CPH2OH)-IRME(CO)PH] AND [(C5ME4CH2CO2H)IRME(CO)CL]

Reaction of [(C5Me5)lrMe(CO)Ph] 1 with sec-butylithium gives a lithio complex, presumably Li[(C5Me4CH2)IrMe(CO)Ph] 2, which reacts with PhCOR to give the appropriately substituted [{C5Me4CH2CPh(OH)R}IrMe(CO)Ph] 3a (R = Me) and 3b (R = Ph). Hydrogen chloride cleaved the Ir-Ph bonds in complexes 3a and 3b to give first [{C5Me4CH2CPh(OH)R}IrMe(CO)Cl] 4, which reacted further with HCl to give [{C5Me4CH2CPh(Me)Cl}Ir(CO)Cl2] 5, from 4a, and [(C5Me4CH = CPh2)Ir(CO)Cl2] 6, from 4b. Complex 2 also reacted with PhCN and with CO2 to give, after work-up, the substituted acetophenone and the substituted acetic acid complexes [(C5Me4CH2COPh)IrMe(CO)Ph] 7 and [(C5Me4CH2CO2H)IrMe(CO)Cl] 8, respectively. Complex 8 was converted by further HCl into [(C5Me4CH2CO2H)Ir(CO)Cl2] 9, or esterified (ROH), base and dicyclohexylcarbodiimide) to give [(C5Me4CH2CO2R)IrMe(CO)Cl] 10a (R = Me) or 10b (R = 1R,2S,5R-menthyl). Complex 9 was also esterified (EtOH, HCl) to give [(C5Me4CH2CO2Et)Ir(CO)Cl2] 11. Reaction of the complex [{C5Me4(CH2SiMe3)}IrMe(CO)Ph] 12 with sec-butyllithium followed by CO2 gave [{C5Me3(CH2-CO2H)(CH2SiMe3)}IrMe(CO)Cl] 13. X-Ray structure determinations of complexes 3b and 8 were carried out: 3b shows no hydrogen bonding, but molecules of 8 are linked across a crystallographic inversion centre by pairs of strong hydrogen bonds between the carboxylic acid residues.