Diiron Aminocarbyne Complexes with NCE(−) Ligands (E = O, S, Se)

Diiron μ-aminocarbyne complexes [Fe(2)Cp(2)(NCMe)(CO)(μ-CO){μ-CN(Me)(R)}]CF(3)SO(3) (R = Xyl, [1a(NCMe)]CF(3)SO(3); R = Me, [1b(NCMe)]CF(3)SO(3); R = Cy, [1c(NCMe)]CF(3)SO(3); R = CH(2)Ph, [1d(NCMe)]CF(3)SO(3)), freshly prepared from tricarbonyl precursors [1a–d]CF(3)SO(3), reacted with NaOCN (in acetone) and NBu(4)SCN (in dichloromethane) to give [Fe(2)Cp(2)(kN-NCO)(CO)(μ-CO){μ-CN(Me)(R)}] (R = Xyl, 2a; Me, 2b; Cy, 2c) and [Fe(2)Cp(2)(kN-NCS)(CO)(μ-CO){μ-CN(Me)(CH(2)Ph)}], 3 in 67–81% yields via substitution of the acetonitrile ligand. The reaction of [1a(NCMe)–1c(NCMe)]CF(3)SO(3) with KSeCN in THF at reflux temperature led to the cyanide complexes [Fe(2)Cp(2)(CN)(CO)(μ-CO){μ-CNMe(R)}], 6a–c (45–67%). When the reaction of [1a(NCMe)]CF(3)SO(3) with KSeCN was performed in acetone at room temperature, subsequent careful chromatography allowed the separation of moderate amounts of [Fe(2)Cp(2)(kSe-SeCN)(CO)(μ-CO){μ-CN(Me)(Xyl)}], 4a, and [Fe(2)Cp(2)(kN-NCSe)(CO)(μ-CO){μ-CN(Me)(Xyl)}], 5a. All products were fully characterized by elemental analysis, IR, and multinuclear NMR spectroscopy; moreover, the molecular structure of trans-6b was ascertained by single crystal X-ray diffraction. DFT calculations were carried out to shed light on the coordination mode and stability of the {NCSe-} fragment.