Baffert Carole, Collomb Marie-Noëlle, Deronzier Alain, Pécaut Jacques, Limburg Julian, Crabtree Robert H, Brudvig Gary W
Laboratoire d'Electrochimie Organique et de Photochimie Rédox, CNRS UMR 5630, Université Joseph Fourier, BP 53, 38041 Grenoble Cedex 9, France.
Inorg Chem. 2002 Mar 25;41(6):1404-11. doi: 10.1021/ic0107375.
Two new terpyridine dimanganese oxo complexes Mn(2)(III,IV)(mu-O)(2)(terpy)(2)(CF(3)CO(2))(2) (3) and [Mn(2)(III,III)(mu-O)(terpy)(2)(CF(3)CO(2))(4)] (4) (terpy = 2,2':6,2' '-terpyridine) have been synthesized and their X-ray structures determined. In contrast to the corresponding mixed-valent aqua complex Mn(2)(III,IV)(mu-O)(2)(terpy)(2)(H(2)O)(2) (1), the two Mn atoms in 3 are not crystallographically equivalent. The neutral binuclear monooxo manganese(III,III) complex 4 exhibits two crystallographic forms having cis and trans configurations. In the cis complex, the two CF(3)CO(2)(-) ligands on each manganese adopt a cis geometry to each other; one CF(3)CO(2)(-) is trans to the oxygen of the oxo bridge while the second is cis. In the trans complex, the two coordinated CF(3)CO(2)(-) have a trans geometry to each other and are cis to the oxo bridge. The electrochemical behavior of 3 in organic medium (CH(3)CN) shows that this complex could be oxidized into its corresponding stable manganese(IV,IV) species while its reduced form manganese(III,III) is very unstable and leads by a disproportionation process to Mn(II) and Mn(IV) complexes. Complex 4 is only stable in the solid state, and it disproportionates spontaneously in CH(3)CN solution into the mixed-valent complex 3 and the mononuclear complex Mn(II)(terpy)(2) (2), thereby preventing the observation of its electrochemical behavior.
已合成两种新型三联吡啶二锰氧配合物Mn₂(III,IV)(μ - O)₂(terpy)₂(CF₃CO₂)₂ (3)和[Mn₂(III,III)(μ - O)(terpy)₂(CF₃CO₂)₄] (4)（terpy = 2,2':6,2'' - 三联吡啶），并确定了它们的X射线结构。与相应的混合价水合配合物Mn₂(III,IV)(μ - O)₂(terpy)₂(H₂O)₂ (1)不同，3中的两个锰原子在晶体学上并不等效。中性双核单氧锰(III,III)配合物4呈现出两种具有顺式和反式构型的晶体形式。在顺式配合物中，每个锰上的两个CF₃CO₂⁻配体彼此呈顺式几何构型；一个CF₃CO₂⁻与氧桥的氧呈反式，而另一个是顺式。在反式配合物中，两个配位的CF₃CO₂⁻彼此呈反式几何构型，且与氧桥呈顺式。3在有机介质（CH₃CN）中的电化学行为表明，该配合物可被氧化为其相应的稳定锰(IV,IV)物种，而其还原形式锰(III,III)非常不稳定，通过歧化过程生成Mn(II)和Mn(IV)配合物。配合物4仅在固态时稳定，它在CH₃CN溶液中自发歧化为混合价配合物3和单核配合物Mn(II)(terpy)₂ (2)，从而无法观察到其电化学行为。
