Piano stool iron complexes with isocyanide ligands

Complexes [FeCpI(CO)(CNR)] [2a-f; R = 2,6-C6H3Me2 = Xyl, 4-C6H4OMe, CH2Ph, CH2P(O)(OEt)2, CH2SO2(4-C6H4Me), Me; Cp = η5-C5H5] and [FeCpI(CNR)2] [3a-f; R = Xyl, 4-C6H4OMe, CH2Ph, CH2P(O)(OEt)2, Me] were obtained in 58-73% yields from the thermal reactions of [FeCpI(CO)2] (1) in toluene with one/two equivalents of CNR, respectively, in the presence of [Fe2Cp2(CO)4] as catalyst. The 1:2 molar reaction of 1 with CNMe resulted in the prevalent formation of [FeCp(CO)(CNMe)2]I, 4f (86% yield). The reactions of 1 and 3a-c with an excess of CF3SO3CH3 afforded the triflate adducts [FeCp(OSO2CF3)L2] (L = CO, 1TF; Xyl, 3aTF; 4-C6H4OMe, 3bTF; CH2Ph, 3cTF), in 62-78% yields, via CH3I elimination. All products were characterized by elemental analysis, IR and multinuclear NMR spectroscopy, moreover the molecular structures of 2a, 2e and 3a were ascertained by single crystal X-ray diffraction. The potential of 1, 2a-f and 3a-f as catalysts in the bulk polymerization of rac-lactide was examined.