New phosphathiamacrocycles containing polypypiridine units

A new 2,2′-bipyridine-based phosphadithiamacrocycle: 3,3′-5-phenyl-2,8-dithia-5-phospha[9]-2,2′-bipyridinophane (L) has been synthesized by reacting 6,6′-bis(bromomethyl)-2,2′-bipyridine and dilithium 3-phenyl-3-phosphapenta-1,5-dithiolate. The phosphoryl derivative: 3,3′-5-oxo-5-phenyl-2,8-dithia-5-phospha[9]-2,2′-bipyridinophane (Lox) synthesized by direct oxidation of L at open atmosphere. Both compounds have been isolated as white solids containing different amounts of LiBr. The reaction of acetonitrile solutions of these solids with Fe(II) perchlorate gave the complexes [FeBr(L)](ClO4) • 2H2O and [FeBr(Lox)](ClO4) • 3H2O, which were crystallized as [FeBr(L)]Br • H2O and [FeBr(Lox)](ClO4)·116MeOH salts from nitromethane or methanol, respectively. Both compounds were characterized by X-ray diffraction analysis. In both cases, a distorted octahedral environment is achieved at the Fe(II), with five sites occupied by the macrocycles L and Lox and the sixth by a monodentate bromine ligand. The bond distances found in the complex cation [FeBr(Lox)]+ are compatible with a high-spin configuration. However, the same parameters for [FeBr(L)]+ and their magnetic character are only compatible with a low-spin configuration. © 2005 Elsevier Ltd. All rights reserved.