Structural studies in the iron(III)/chloride/α,α'-diimine system. III. Crystal structures of Tris(2,2'-bipyridine)iron(II) μ-Oxo-bis[trichloroferrate(III)] and of 'Compound A', μ-Oxo-bis[cis-chlorobis(1 ,10-phenanthroline)iron(III)] chloride solvate

Abstract

The crystal structure of [Fe(bpy)₃] [CI₃FeOFeCI₃] (1) has been determined by single-crystal X-ray diffraction at 295 K, and refined by least squares to a residual of 0.058 for 2002 'observed' reflections. Crystals are monoclinic, P2₁/c, a 9.616(3), b 26.264(6), c 13.821(7) Ǻ, β 99.68(2)°, Z4. In the cation, Fe-N distances range from 1.956(9) to 1 .989(10) Ǻ; in the anion, Fe-Cl distances range from 2.196(5) to 2.225(5) Ǻ. Fe-O distances are 1.763(11) and 1.740(11) Ǻ, and the Fe-O-Fe angle is 148.9(7)°. Recrystallization of 'compound A' from methanolic aqueous solution yields crystals with stoichiometry [{cis-Fe(phen)₂Cl}₂O]Cl₂.nH₂O( n ≈ 4.5) as established by structure determination (hampered by serious disorder); R is 0.09 for 749 'observed' reflections. Crystals are orthorhombic, Pcn2, a 18.05(1), b 13.83(1), c 10.481(6) Ǻ, Z 2. The Fe-N distances trans to each other are 2.12(3) and 2.13(3) Ǻ; Fe-N distances trans to Cl and O are 2.20(2) and 2.28(2) Ǻ, respectively. Fe-CI is 2.34(1) and Fe-O 1.787(6) A; Fe-O-Fe is 161(1)°. For crystals from aqueous solution, an isomorphous but larger unit cell is obtained [2754(7), cf. 2616(3) Ǻ³]; it is believed that this is a consequence of variable occupancy of the disordered solvent layers which lie parallel to bc between the ionic species.