Piano stool iron complexes with isocyanide ligands.

• Cyclopentadienyl iron complexes with a range of isocyanide ligands have been synthesized and characterized. • The reactions with methyl triflate proceed with abstraction of the iodide ligand rather than isocyanide alkylation. • The complexes are catalytically active in the ring opening polymerization of rac -lactide. Complexes [FeCpI(CO)(CNR)] [ 2a-f ; R = 2,6-C 6 H 3 Me 2 = Xyl, 4-C 6 H 4 OMe, CH 2 Ph, CH 2 P(O)(OEt) 2 , CH 2 SO 2 (4-C 6 H 4 Me), Me; Cp = η5-C 5 H 5 ] and [FeCpI(CNR) 2 ] [ 3a-f ; R = Xyl, 4-C 6 H 4 OMe, CH 2 Ph, CH 2 P(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 [Fe 2 Cp 2 (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 CF 3 SO 3 CH 3 afforded the triflate adducts [FeCp(OSO 2 CF 3)L 2 ] (L = CO, 1TF ; Xyl, 3aTF ; 4-C 6 H 4 OMe, 3bTF ; CH 2 Ph, 3cTF), in 62-78% yields, via CH 3 I 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. [Display omitted] [ABSTRACT FROM AUTHOR]