Unusual thiophene complexes from reactions of Cp*Ir(2,5-dimethylthiophene) with sources of W(CO)5, Cr(CO)4, Mo(CO)4, and Fe(CO)3

The isomers, Cp*Ir(η4-2,5-Me2T) (1) and Cp*Ir(C,S-2,5-Me2T) (2), where 2,5-Me2T is 2,5-dimethylthiophene, are observed to coordinate to metal carbonyl fragments in various ways when reacted with metal complexes W(CO)5(THF), Cr(CO)4(COD), Mo(CO)4(NBD) and Fe(CO)3(BDA), that contain readily displaceable ligands (COD=1,5-cyclooctadiene, NBD=norbornadiene, BDA=benzylidene acetone). In Cp*Ir(η4-2,5-Me2T·M(CO)5), the M(CO)5 unit (M=Cr, Mo, or W) is coordinated to the sulfur atom of 1. The iridathiabenzene ring of 2 coordinates to a M(CO)3 moiety through all six atoms in [η6-Cp*Ir(C,S-2,5-Me2T)]M(CO)3, where M=Cr or Mo. The iridathiabenzene ring in the CO adduct of 2, Cp*Ir(C,S-2,5-Me2T)(CO), coordinates through the sulfur to W(CO)5 in 6, Cp*Ir[C,S-2,5-Me2T·W(CO)5](CO), and through five atoms (not the Ir) to Cr(CO)3 in 14, Cp*Ir(C,S-2,5-Me2T·Cr(CO)5)(CO). Structures of 6 and 14 are reported.