Iron carbonyl complexes from 2-[2,3-diaza-4-(2-thienyl)buta-1,3-dienyl]thiophene: N-N bond cleavage and cyclometalation

When thienyl Schiff base 1, derived from 2-formylthiophene and hydrazine, reacted with Fe-2(CO)(9) in n-hexane, three major complexes were obtained: (1) a diironhexacarbonyl complex with two 2-thienyhnethylideneamido bridging ligands 2, which resulted from the =N-N= bond cleavage of ligand 1; (2) a doubly cyclometalated di-mu -di-(eta (1):eta (2)-thienyl; eta (1):eta (1)(N))bis(hexacarbonyldiiron) complex (3); and (3) a cyclometalated (mu-eta (1):eta (2)-thienyl; eta (1):eta (1)(N))hexacarbonyldiiron complex (4). Molecular structures of compounds 1a, 1c, and 2a have been determined by single-crystal X-ray diffraction. (C) 2001 Elsevier Science B.V. All rights reserved.