Preparation and characterization of carbene complexes of iron from azolyl and thienyl precursors

Azolyl and thienyl iron(II) complexes have been synthesized by the addition of 1-phenylpyrazol-5-yllithium, 5-(4,5-dihydro-4,4-dimethyloxazolin-2-yl)-2-thienyllithium, 2-(4,5-dihydro-4,4-dimethyloxazolin-2-yl)-3-thienyllithium or 5-(2-pyridyl)-2-thienyllithium to [Fe(cp)(CO)2Cl](cp =η-C5H5). Protonation or alkylation of these precursor complexes yielded the corresponding amino(organo)-, organo(thio)- or heterometallacyclic alkoxy(amino)- and hydroxy(amino)-carbene complexes as well as compounds in which the ligand shows more pyridinium character. The molecular structures of the pyrazolyl complex [Fe(cp)(CO)2([graphic omitted]Ph)] and the pyrazolinylidene complex [Fe(cp)(CO)2([graphic omitted]Ph)][CF3SO3] have iron–carbon bond lengths of 1.981(2) and 1.969(5)A respectively.