Synthesis, structure, and reactivity of novel iron(II) complexes with a five-membered chelate ligand κ2(Si,N)-SiMe2O(2-C5H4N)

Photolysis of Cp′(CO)2FeSiMe2O(2-C5H4N) (1a: Cp′=η5-C5H5 (Cp), 1b: Cp′=η5-C5Me5 (Cp*)) afforded Cp′(CO)Fe[κ2(Si,N)-SiMe2O(2-C5H4N)] (2a: Cp′=Cp, 2b: Cp′=Cp*) in good yield each. These cyclic compounds also formed in moderate yields through photoreaction of Cp′(CO)2FeSiMe3 with HSiMe2O(2-C5H4N) (3). Single-crystal X-ray diffraction study confirmed the structure of 2b containing a five-membered chelate ring comprised of Fe, Si, O, C, and N. Complexes 2a and 2b were thermally stable and did not react with slight excess of PR3 (R=Me, Ph) in benzene-d6 solution below 80 °C. Above 80 °C, 2a reacted slowly with PR3 to give Cp(CO)(PR3)FeSiMe2O(2-C5H4N) (6: R=Me, 7: R=Ph) accompanied by the cleavage of the FeN bond. These results indicate that both FeSi bond and FeN bond in 2 are notably sturdy.