3 research outputs found
Symmetric and asymmetric dinuclear manganese(IV) complexes possessing a [Mn<SUP>IV</SUP><SUB>2</SUB>(μ-O)<SUB>2</SUB>(μ-O<SUB>2</SUB>CMe)]<SUP>3+</SUP> core and terminal Cl<SUP>-</SUP> ligands
No full textThe synthesis of new dinuclear manganese(IV) complexes possessing the [Mn<SUP>IV</SUP><SUB>2</SUB>(μ-O)<SUB>2</SUB>(μ-O<SUB>2</SUB>CMe)]<SUP>3+</SUP> core and containing halide ions as terminal ligands is reported. [Mn<SUB>2</SUB>O<SUB>2</SUB>(O<SUB>2</SUB>CMe)Cl<SUB>2</SUB>(bpy)<SUB>2</SUB>]<SUB>2</SUB>[MnCl<SUB>4</SUB>] (1; bpy = 2,2'-bipyridine) was prepared by sequential addition of [MnCl<SUB>3</SUB>(bpy)(H<SUB>2</SUB>O)] and (NBzEt<SUB>3</SUB>)<SUB>2</SUB>[MnCl<SUB>4</SUB>] to a CH<SUB>2</SUB>Cl<SUB>2</SUB> solution of [Mn<SUB>3</SUB>O<SUB>4</SUB>(O<SUB>2</SUB>CMe)<SUB>4</SUB>(bpy)<SUB>2</SUB>]. The complex [Mn<SUP>IV</SUP><SUB>2</SUB>O<SUB>2</SUB>(O<SUB>2</SUB>CMe)Cl(bpy)<SUB>2</SUB>(H<SUB>2</SUB>O)](NO<SUB>3</SUB>)<SUB>2</SUB> (2) was obtained from a water/acetic acid solution of MnCl<SUB>2</SUB>·4H<SUB>2</SUB>O, bpy, and (NH<SUB>4</SUB>)<SUB>2</SUB>[Ce(NO<SUB>3</SUB>)<SUB>6</SUB>], whereas the [Mn<SUP>IV</SUP><SUB>2</SUB>O<SUB>2</SUB>(O<SUB>2</SUB>CR)X(bpy)<SUB>2</SUB>(H<SUB>2</SUB>O)](ClO<SUB>4</SUB>)<SUB>2</SUB> [X = Cl<SUP>-</SUP> and R = Me (3), Et (5), or C<SUB>2</SUB>H<SUB>4</SUB>Cl (6); and X = F<SUP>-</SUP>, R = Me (4)] were prepared by a slightly modified procedure that includes the addition of HClO<SUB>4</SUB>. For the preparation of 4, MnF<SUB>2</SUB> was employed instead of MnCl<SUB>2</SUB>·4H<SUB>2</SUB>O. [Mn<SUB>2</SUB>O<SUB>2</SUB>(O<SUB>2</SUB>CMe)Cl<SUB>2</SUB>(bpy)<SUB>2</SUB>]<SUB>2</SUB>[MnCl<SUB>4</SUB>]·2CH<SUB>2</SUB>Cl<SUB>2</SUB> (1·2CH<SUB>2</SUB>Cl<SUB>2</SUB>) 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) Å<SUP>3</SUP>, and Z = 4. [Mn<SUB>2</SUB>O<SUB>2</SUB>(O<SUB>2</SUB>CMe)Cl(H<SUB>2</SUB>O)(bpy)<SUB>2</SUB>](NO<SUB>3</SUB>)<SUB>2</SUB>·H<SUB>2</SUB>O (2·H<SUB>2</SUB>O) 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) Å<SUP>3</SUP>, and Z = 2. [Mn<SUB>2</SUB>O<SUB>2</SUB>(O<SUB>2</SUB>CMe)Cl(H<SUB>2</SUB>O)(bpy)<SUB>2</SUB>](ClO<SUB>4</SUB>)<SUB>2</SUB>·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) Å<SUP>3</SUP>, and Z = 2. The cyclic voltammogram (CV) of 1 exhibits two processes, an irreversible oxidation of the [MnCl<SUB>4</SUB>]<SUP>2-</SUP> at E<SUB>½</SUB> ~0.69 V vs ferrocene and a reversible reduction at E<SUB>½</SUB>= 0.30 V assigned to the [Mn<SUB>2</SUB>O<SUB>2</SUB>(O<SUB>2</SUB>CMe)Cl<SUB>2</SUB>(bpy)<SUB>2</SUB>]<SUP>+/0</SUP> couple (2Mn<SUP>IV</SUP> to Mn<SUP>IV</SUP>Mn<SUP>III</SUP>). In contrast, the CVs of 2 and 3 show only irreversible reduction features. Solid-state magnetic susceptibility (X<SUB>M</SUB>) data were collected for complexes 1·1.5H<SUB>2</SUB>O, 2·H<SUB>2</SUB>O, and 3·H<SUB>2</SUB>O in the temperature range 2.00-300 K. The resulting data were fit to the theoretical X<SUB>M</SUB> T vs T expression for a Mn<SUP>IV</SUP><SUB>2</SUB> complex derived by use of the isotropic Heisenberg spin Hamiltonian (η= -2JS<SUB>1</SUB>S<SUB>2</SUB>) and the Van Vleck equation. The obtained fit parameters were (in the format J/g) -45.0(4) cm<SUP>-1</SUP>/2.00(2), -36.6(4) cm<SUP>-1</SUP>/1.97(1), and -39.3(4) cm<SUP>-1</SUP>/1.92(1), respectively, where J is the exchange interaction parameter between the two Mn<SUP>IV</SUP> ions. Thus, all three complexes are antiferromagnetically coupled
