LEWIS ACID ADDUCTS (BH3, ME+, AND ET+) OF THE ETA-4 AND ETA-2 ISOMERS OF CP-STAR-IR(THIOPHENE)

The i;4-thiophene complex Cp*Ir(η4-2,5-Me2T) (2), where 2,5-Me2T is 2,5-dimethylthiophene, reacts with Me2S-BH3 to give the BH3 adduct Cp*Ir(η4-2,5-Me2T-BH3) (6), demonstrating the unusually high basicity of the sulfur in 2 as compared with that in Me2S. Basic amines remove the BH3 in 6 to give 2. Surprisingly,[inline formula omitted] the isomer Cp*Ir(η4-2,5-Me2T) also reacts with Me2S-BH3 to give 6. The 2-methylthiophene analogues of 2 and 4 react similarly to give Cp*Ir(η4-2,5-Me2T-BH3) (5), whose structure was determined by X-ray diffraction. Complex 2 also reacts with R3O+ (R = Me, Et) to give the S-alkylated thiophene complexes Cp*Ir(η4-2,5-Me2T-R)+. © 1990, American Chemical Society. All rights reserved.