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 (k N -NCO)(CO)(μ-CO){μ-CN(Me)(R)}] (R = Xyl, 2a ; Me, 2b ; Cy, 2c ) and [Fe 2 Cp 2 (k N -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 (k Se -SeCN)(CO)(μ-CO){μ-CN(Me)(Xyl)}], 4a , and [Fe 2 Cp 2 (k N -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 {NC Se -} fragment.