The coordination chemistry of mixed pyridine-phenol and phenanthroline-phenol ligands; The crystal structure of 2-(2-hydroxyphenyl)-1,10-phenanthroline (HL) and the crystal structure and properties of [FeL 2][PF 6

Abstract

The crystal structures of the N,N,O-terdentate ligand 2-(2-hydroxyphenyl)-1,10-phenanthroline (HL) and its Fe(III) complex [FeL 2][PF 6] ( 1) have been determined. In HL, an intramolecular OH … N hydrogen bond between the phenolic OH and the adjacent nitrogen atom of the phenanthroline fragment constrains these two donor atoms to be cisoid, with the proton ‘chelated’. The molecules of HL are associated into pairs in the crystal via a face-to-face aromatic π-stacking interaction. Complex 1 has a conventional distorted octahedral structure; sections of the aromatic ligands overlap between adjacent molecules to form an interleaved stack. It is high-spin down to 83 K, and its EPR spectrum (frozen glass at 77 K) is entirely typical of a rhombically distorted high-spin Fe III site.