Bhaduri, Sumit ; Tasiopoulos, Anastasios J. ; Bolcar, Milissa A. ; Abboud, Khalil A. ; Streib, William E. ; Christou, George (2003) Symmetric and asymmetric dinuclear manganese(IV) complexes possessing a [MnIV2(μ-O)2(μ-O2CMe)]3+ core and terminal Cl- ligands Inorganic Chemistry, 42 (5). pp. 1483-1492. ISSN 0020-1669
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Official URL: http://pubs.acs.org/doi/abs/10.1021/ic020570v
Related URL: http://dx.doi.org/10.1021/ic020570v
Abstract
The synthesis of new dinuclear manganese(IV) complexes possessing the [MnIV2(μ-O)2(μ-O2CMe)]3+ core and containing halide ions as terminal ligands is reported. [Mn2O2(O2CMe)Cl2(bpy)2]2[MnCl4] (1; bpy = 2,2'-bipyridine) was prepared by sequential addition of [MnCl3(bpy)(H2O)] and (NBzEt3)2[MnCl4] to a CH2Cl2 solution of [Mn3O4(O2CMe)4(bpy)2]. The complex [MnIV2O2(O2CMe)Cl(bpy)2(H2O)](NO3)2 (2) was obtained from a water/acetic acid solution of MnCl2·4H2O, bpy, and (NH4)2[Ce(NO3)6], whereas the [MnIV2O2(O2CR)X(bpy)2(H2O)](ClO4)2 [X = Cl- and R = Me (3), Et (5), or C2H4Cl (6); and X = F-, R = Me (4)] were prepared by a slightly modified procedure that includes the addition of HClO4. For the preparation of 4, MnF2 was employed instead of MnCl2·4H2O. [Mn2O2(O2CMe)Cl2(bpy)2]2[MnCl4]·2CH2Cl2 (1·2CH2Cl2) crystallizes in the monoclinic space group C2/c with a = 21.756(2) Å, b = 12.0587(7) Å, c = 26.192(2) Å, α = 90°, β= 111.443(2)°,γ = 90°, V = 6395.8(6) Å3, and Z = 4. [Mn2O2(O2CMe)Cl(H2O)(bpy)2](NO3)2·H2O (2·H2O) crystallizes in the triclinic space group P↑ with a = 11.907(2) Å, b = 12.376(2) Å, c = 10.986(2) Å, α= 108.24(1)°, β= 105.85(2)°, γ= 106.57(1)°, V = 1351.98(2) Å3, and Z = 2. [Mn2O2(O2CMe)Cl(H2O)(bpy)2](ClO4)2·MeCN (3·MeCN) crystallizes in the triclinic space group P with a = 11.7817(7) Å, b = 12.2400(7) Å, c = 13.1672(7) Å, α= 65.537(2)°, β= 67.407(2)°, γ= 88.638(2)°, V = 1574.9(2) Å3, and Z = 2. The cyclic voltammogram (CV) of 1 exhibits two processes, an irreversible oxidation of the [MnCl4]2- at E½ ~0.69 V vs ferrocene and a reversible reduction at E½= 0.30 V assigned to the [Mn2O2(O2CMe)Cl2(bpy)2]+/0 couple (2MnIV to MnIVMnIII). In contrast, the CVs of 2 and 3 show only irreversible reduction features. Solid-state magnetic susceptibility (XM) data were collected for complexes 1·1.5H2O, 2·H2O, and 3·H2O in the temperature range 2.00-300 K. The resulting data were fit to the theoretical XM T vs T expression for a MnIV2 complex derived by use of the isotropic Heisenberg spin Hamiltonian (η= -2JS1S2) and the Van Vleck equation. The obtained fit parameters were (in the format J/g) -45.0(4) cm-1/2.00(2), -36.6(4) cm-1/1.97(1), and -39.3(4) cm-1/1.92(1), respectively, where J is the exchange interaction parameter between the two MnIV ions. Thus, all three complexes are antiferromagnetically coupled.
| Item Type: | Article |
|---|---|
| Source: | Copyright of this article belongs to American Chemical Society. |
| ID Code: | 1942 |
| Deposited On: | 08 Oct 2010 11:17 |
| Last Modified: | 11 May 2012 11:18 |
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