Notes. Reaction of elemental sulphur with (5H,14H-6,8,15,17-tetramenthyldibenzo [b,i][1,4,8,11]tetra-azacyclotetradecinato)iron(II):synthesis and X-ray structure of a µ-sulphido iron (III) complex

Abstract

The reaction of (5H,14H-6,8,15,17-tetramethyldibenzo [b,i][1,4,8,11] tetra-azacycloteradecinato)iron(II), [Fe(tmdbted)](1), with elemental sulpur under very mildconditions in tetrahydrofuran (thf) leads to quantitaitve formation of the correponding µ-sulphido complex, [{Fe (tmdbted)}₂(µ-S)]·thf (2). Complex (2) has µ_eff= 2.43 B.M. at 292 K, indicating an antiferromagnetic coupling between the two iron (III) high-spin centres. The X-ray analysis on complex (2) showed the typical ‘saddle’ shape for the macrocyclic ligand. The square-pyramidal co-ordination geometry and bond parameters indicate high-spin iron (III): the average displacement of the Fe^III from the N₄ donor plane is –0.698 (2)Å, while the average Fe–N distance is 2.055 Å. The Fe–S–Fe angle is significantly narrower[126.3(1)°] than the corresponding value of Fe–O–Fe (142.75°) in [{Fe(tmdbted)}₂(µ-O)]·MeCN.