Conformation of a MnCp(CO)2-thienothiophene carbene complex: A spectroscopic and computational study

The carbene complex [MnCp(CO)2C(OEt)(TT)], (TT = 3,6-dimethylthieno[3,2-b]thiophene) 1, was synthesized according to the classical Fischer method. The novel complex was fully characterized using various spectroscopic techniques. The infrared spectrum of the complex, recorded as a solution in dichloromethane, revealed a four-band spectrum in the carbonyl region instead of the expected two-band spectrum. A density functional theory (DFT) study was undertaken to explain the presence of more than one conformer in solution. The crystal structure of 1 is reported.