O-Alkylthio- and O-alkylselenooxalate iron complexes: Structures of CpFe(CO)2ECOCO2Me and [CpFe(CO)2ECO]2

When the iron sulfide complexes (μ-Sx)[CpFe(CO)2]2 (x = 2, 3) are treated with O-alkyl oxalyl chlorides ROCOCOCl the complexes CpFe(CO)2SCOCO2R (1) [R = Me (a), Et (b)] are obtained. Similarly, the complexes CpFe(CO)2SeCOCO2R (2) are obtained from the analogous iron selenide (μ-Se)[CpFe(CO)2]2 reaction with the same reagents. Treatment of the iron selenide with half equivalent of oxalyl chloride produces the dimeric complex [CpFe(CO)2SeCO]2 (3). The new complexes, 1, 2 and 3, have been characterized by elemental analyses, IR and 1H NMR spectroscopy. The solid state structures of 1a, 2a, 3 and [CpFe(CO)2SCO]2 (4) were determined by an X-ray crystal structure analysis.