New phosphathiamacrocycles containing polypypiridine units

• Published in: Polyhedron 2006-02, Vol.25 (3), p.801-808
• Main Authors: Escriche, Lluis, Casabó, Jaume, Muns, Vicens, Kivekäs, Raikko, Sillanpää, Reijo
• Format: Article
• Language: English
• Subjects: Iron(II) complexes; Phosphathiamacrocycles; Polypyridine
• ISSN: 0277-5387
• DOI: 10.1016/j.poly.2005.08.006

The first example of phosphathiamacrocycles containing polypyridine units L and Lox are reported. Their reaction in front of Fe(II) gives in both cases octahedral complexes with a low-spin configuration for L and high-spin for Lox. 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)](ClO 4) · 2H 2O and [FeBr(Lox)](ClO 4) · 3H 2O, which were crystallized as [FeBr(L)]Br · H 2O and [ FeBr ( Lox ) ] ( ClO 4 ) · 1 1 6 MeOH 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.