Syntheses and structures of iron carbonyl complexes derived from N-(5-methyl-2-thienylmethylidene)-2-thiolethylamine and N-(6-methyl-2-pyridylmethylidene)-2-thiolethylamine

The reaction of N-(5-methyl-2-thienylmethylidene)-2-thiolethylamine (1) with Fe2(CO)9 in refluxing acetonitrile yielded di-(μ3-thia)nonacarbonyltriiron (2), μ-[N-(5-methyl-2-thienylmethyl)-η1:η1(N);η1:η1(S)-2-thiolatoethylamido]hexacarbonyldiiron (3), and N-(5-methyl-2-thienylmethylidene)amine (4). If the reaction was carried out at 45 °C, di-μ-[N-(5-methyl-2-thienylmethylidene)-η1(N);η1(S)-2-thiolethylamino]-μ-carbonyl-tetracarbonyldiiron (5) and trace amount of 4 were obtained. Stirring 5 in refluxing acetonitrile led to the thermal decomposition of 5, and ligand 1 was recovered quantitatively. However, in the presence of excess amount of Fe2(CO)9 in refluxing acetonitrile, complex 5 was converted into 2–4. On the other hand, the reaction of N-(6-methyl-2-pyridylmethylidene)-2-thiolethylamine (6) with Fe2(CO)9 in refluxing acetonitrile produced 2, μ-[N-(6-methyl-2-pyridylmethyl)-η1 (Npy);η1:η1(N); η1:η1(S)-2-thiolatoethylamido]pentacarbonyldiiron (7), and μ-[N-(6-methyl-2-pyridylmethylidene)-η2(C,N);η1:η1(S)-2- thiolethylamino]hexacarbonyldiiron (8). Reactions of both complex 7 and 8 with NOBF4 gave μ-[(6-methyl-2-pyridylmethyl)-η1(Npy);η1:η1(N);η1:η1(S)-2-thiolatoethylamido](acetonitrile)tricarbonylnitrosyldiiron (9). These reaction products were well characterized spectrally. The molecular structures of complexes 3, 7–9 have been determined by means of X-ray diffraction. Intramolecular 1,5-hydrogen shift from the thiol to the methine carbon was observed in complexes 3, 7, and 9.