(μ-Oxo)diiron Complexes of Gated Glyoximes. Structural Changes Accompanying Ligation Trans to the Oxo Bridge

• Published in: Inorganic chemistry 1996-03, Vol.35 (7), p.2006-2010
• Main Authors: Vernik, Isak, Stynes, Dennis V
• Format: Article
• Language: English
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/ic950801g

Structures of new low-spin oxo-bridged complexes of bis[(diphenylboryl)dimethylglyoximato]iron, Fe((DMG)BPh2)2, are reported. The pentacoordinate complex, 1 = [Fe((DMG)BPh2)2]2O, contains a bent Fe−O−Fe bridge (166.0°) with the irons each displaced 0.3 Å out of the N4 planes toward the oxo ligand. The Fe−μ-O bond length (1.7097(10) Å) is the shortest yet reported. Both axial phenyl groups are directed to the trans face, creating a superstructure which is collapsed around the vacant binding site. In the butylamine derivative, 2 = [(BuNH2)Fe((DMG)BPh2)2)]2O, the Fe−O−Fe bridge is linear (178.6°) with iron in the N4 plane and Fe−O bond lengths of 1.766(6) Å. The BuNH2 ligand is sandwiched between the axial phenyl groups in intimate contact with them. Structural changes accompanying ligation and their consequences are compared with those in heme systems. Crystal data for 1:  orthorhombic, Pnna, a = 17.440(3) Å, b = 21.381(4) Å, c = 16.896(3) Å, V = 6300(2) Å3, Z = 4, R = 0.068. Crystal data for 2 (CHCl3 disolvate):  triclinic, P1̄, a = 13.445(3) Å, b = 14.525(4) Å, c = 23.877(6) Å, α = 96.01°, β = 92.61°, γ = 117.40(1)°, V = 4094(2) Å3, Z = 2, R = 0.086.