The Electron Transfer Series [MoIII(bpy)3]n (n=3+, 2+, 1+, 0, 1−), and the Dinuclear Species [{MoIIICl(Mebpy)2}2(μ2-O)]Cl2 and [{MoIV(tpy.)2}2(μ2-MoO4)](PF6)2⋅4 MeCN
Abstract
The electronic structures of the five members of the electron transfer series [Mo(bpy)3]n (n=3+, 2+, 1+, 0, 1−) are determined through a combination of techniques: electro- and magnetochemistry, UV/Vis and EPR spectroscopies, and X-ray crystallography. The mono- and dication are prepared and isolated as PF6 salts for the first time. It is shown that all species contain a central MoIII ion (4d3). The successive one-electron reductions/oxidations within the series are all ligand-based, involving neutral (bpy0), the π-radical anion (bpy.)1−, and the diamagnetic dianion (bpy2−)2−: [MoIII(bpy0)3]3+ (S=3/2), [MoIII(bpy.)(bpy0)2]2+ (S=1), [MoIII(bpy.)2(bpy0)]1+ (S=1/2), [MoIII(bpy.)3] (S=0), and [MoIII(bpy.)2(bpy2−)]1− (S=1/2). The previously described diamagnetic dication “[MoII(bpy0)3](BF4)2” is proposed to be a diamagnetic dinuclear species [{Mo(bpy)3}2(μ2-O)](BF4)4. Two new polynuclear complexes are prepared and structurally characterized: [{MoIIICl(Mebpy0)2}2(μ2-O)]Cl2 and [{MoIV(tpy.)2}2(μ2-MoVIO4)](PF6)2⋅4 MeCN.
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