Alkoxo-verbindungen des dreiwertigen eisen: Synthese und charakterisierung von [Fe2(OtBu)6], [Fe2Cl2(OtBu)4], [Fe2Cl4(OtBu)2] und [N(nBu)4]2[Fe6OCl6(OMe) 12]

Abstract

The reaction of iron(III)chloride in diethylether with sodium tert-butylat yielded the homoleptic dimeric tert-butoxide Fe2(OtBu)6 (1). The chloro-derivatives [Fe2Cl2(OtBu)4] (2), and [Fe2Cl4(OtBu)2] (3) could be synthesized by ligand exchange between 1 and iron(III)chloride. Each of the molecules 1, 2, and 3 consists of two edge-sharing tetrahedrons, with two tert-butoxo-groups as μ2-bridging ligands. For the synthesis of the alkoxides 1, 2, and 3 diethylether plays an important role. In the first step the dietherate of iron(III)chloride FeCl3(OEt2)2 (4) is formed. The reaction of iron(III)chloride with tetrabutylammonium methoxide in methanol results in the formation of a tetrabutylammonium methoxo-chloro-oxo-hexairon cluster [N(nBu)4]2[Fe6OCl6(OMe) 12] (5). Crystal structure data: 1, triclinic, P1̄, a = 9.882(2) Å, b = 10.523(2) Å, c = 15.972(3) Å, a = 73.986(4)°, β = 88.713(4)°, γ = 87.145(4)°, V = 1594.4(5) Å3, Z = 2, dc = 1.146 gcm-1, R1 = 0.044; 2, monoclinic, P21/n, a = 11.134(2) Å, b = 10.141(2) Å, c = 12.152(2) Å und β = 114.157(3)°, V = 1251.8(4) Å3, Z = 2, dc = 1.377 gcm-1, R1 = 0.0581; 3, monoclinic, P21/n, a = 6.527(2) Å, b = 11.744(2) Å, c = 10.623(2), β = 96.644(3)°, V = 808.8(2) Å3, Z = 2, dc = 1.641 gcm-1, R1 = 0.0174; 4, orthorhombic, Iba2, a = 23.266(5) Å, b = 9.541(2) Å, c = 12.867(3) Å, V = 2856(2) Å3, Z = 8, dc= 1.444 gcm-1, R1 = 0.0208; 5, trigonal, P31, a = 13.945(2) Å, c = 30.011(6) Å, V = 5054(2) Å3, Z = 6, dc = 1.401 gcm-1; R1 = 0.0494.