DESIGN, SYNTHESIS, AND CHARACTERIZATION OF BIS(MU-OXO)DIMANGANESE(III,III) COMPLEXES - STERIC AND ELECTRONIC CONTROL OF REDOX POTENTIALS
DESIGN, SYNTHESIS, AND CHARACTERIZATION OF BIS(MU-OXO)DIMANGANESE(III,III) COMPLEXES - STERIC AND ELECTRONIC CONTROL OF REDOX POTENTIALS
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DOI：
10.1021/ja00173a011
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发表时间：
1990-08-15
影响因子：
15
通讯作者：
HODGSON, DJ
中科院分区：
文献类型：
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作者：
GOODSON, PA;OKI, AR;HODGSON, DJ
本文报道了三个双(U-氧)二锰(III，III)配合物和一个双(U-氧)二锰(III，IV)配合物的合成。锰(III/III)配合物均为[(L)MnO]22+，其中配体L与N，N‘-二(2-吡啶甲基)-1，2-乙二胺(双)和三(2-吡啶甲基)胺(Tmpa，2a)有关。配合物双(MU-氧代)双[N，N‘’-bis((6-methylpyrid-2-yl)methyl)ethane-1，2-diamine]dimanganese(III)高氯酸盐，[(1b)-MnO]2(ClO4)2.cntdot.H2O，Mn2C32H46Cl2N8O11(4)，结晶在三斜空间群P.hivin1中，在一个晶胞中有两个双核配合物，a=8.487(3).ANG，b=10.868(2).ANG，c=20.816(5).=77.34(2)度、β=88.28(2)度及伽马=84.02(2)度根据2,787次独立观测，该结构已被改进为传统的R因子值0.0759。双(MU-氧代)双[N，N-bis((6-methylpyrid-2-yl)methyl)-N-2-pyridylmethylamine]dimanganese(III)硝酸盐六水合物，[(2c)MnO]2(NO3)2.cntdot.6H2O，Mn2C40H56N10O14(5)，属单斜晶系C2/c空间群，晶胞尺寸为a=22.122(7)，b=16.419(6)，c=14.461(4)。=117.15(2)度根据1,396次独立观测，该结构的R系数已细化至0.0683。双(MU-氧代)双[N，N‘’-bis(2-methylpyrazyl)-ethane-1，2-diamine]dimanganese(III)高氯酸盐七水合物，[(1D)MnO]2(ClO4)2.cntdot.7H2O，Mn2C24H46Cl2N12O17(7)，结晶在单斜晶系C2空间群中，在a=21.371(5)的晶胞中有四个双核配合物，b=9.301(3)，c=21.180(7)。=108.54(2)度根据3,766次独立观测，该结构的R值已细化至0.0515。所有的配合物都含有异构体，其中取代的吡啶(或吡嗪)基团相对于桥式氧基横轴排列在金属周围。配合物4和5显示出很长的轴向Mn.sbd.N键，这可以归因于吡啶环上6-甲基的存在，这种空间约束被证明是这些配合物中Mn(III，III)形式稳定的原因。在络合物7中，III/III形式的稳定是从吡啶(pKa=5.20)转变为吡嗪(pKa=0.65)的电子结果。循环伏安图4和5表明，两个氧化还原波在每种情况下都相对于母体双比肯和tmpa络合物在正方向上移动了约0.4V。化合物5的完全氧化形式已被证明是一种双电子电催化氧化剂，选择性地将苯甲醇氧化为苯甲醛。
The synthesis of three bis(.mu.-oxo)dimanganese(III,III) complexes and one bis(.mu.-oxo)dimanganese(III,IV) complex are described. The Mn(III/III) complexes are all of the general formulation [(L)MnO]22+, where the ligands L are related to N,N''-bis(2-pyridylmethyl)-1,2-ethanediamine (bispicen, 1a) and tris(2-pyridylmethyl)amine (tmpa, 2a). The complex bis(.mu.-oxo)bis[N,N''-bis((6-methylpyrid-2-yl)methyl)ethane-1,2-diamine]dimanganese(III) perchlorate monohydrate, [(1b)-MnO]2(ClO4)2.cntdot.H2O, Mn2C32H46Cl2N8O11 (4), crystallizes in the triclinic space group P.hivin.1 with two binuclear complexes in a cell of dimensions a = 8.487 (3) .ANG., b = 10.868 (2) .ANG., c = 20.816 (5) .ANG., .alpha. = 77.34 (2).degree., .beta. = 88.28 (2).degree., and .gamma. = 84.02 (2).degree.. The structure has been refined to a value of the conventional R factor of 0.0759 based on 2787 independent observations. The complex bis(.mu.-oxo)bis[N,N-bis((6-methylpyrid-2-yl)methyl)-N-2-pyridylmethylamine]dimanganese(III) nitrate hexahydrate, [(2c)MnO]2(NO3)2.cntdot.6H2O, Mn2C40H56N10O14 (5), crystallizes in the monoclinic space group C2/c with four binuclear complexes in a cell dimensions a = 22.122 (7) .ANG., b = 16.419 (6) .ANG., c = 14.461 (4) .ANG., .beta. = 117.15 (2).degree.. The structure has been refined to an R factor of 0.0683 based on 1396 independent observations. The complex bis(.mu.-oxo)bis[N,N''-bis(2-methylpyrazyl)-ethane-1,2-diamine]dimanganese(III) perchlorate heptahydrate, [(1d)MnO]2(ClO4)2.cntdot.7H2O, Mn2C24H46Cl2N12O17 (7), crystallizes in the monoclinic space group C2 with four binuclear complexes in a cell of dimensions a = 21.371 (5) .ANG., b = 9.301 (3) .ANG., c = 21.180 (7) .ANG., .beta. = 108.54 (2).degree.. The structure has been refined to an R value of 0.0515 based on 3766 independent observations. The complexes are all found to contain the isomer in which the substituted pyridine (or the pyrazine) groups are trans axially disposed around the metal relative to the bridging oxo groups. Complexes 4 and 5 display very long axial Mn.sbd.N bonds which can be attributed to the presence of the 6-methyl groups on the pyridine rings, and this steric constraint has been demonstrated to be the cause of the stabilization of the Mn(III,III) form in these complexes. In complex 7, the stabilization of the III/III form is an electronic consequence of the change from pyridine (pKa = 5.20) to pyrazine (pKa = 0.65). Cyclic voltammograms of 4 and 5 show that the two redox waves are shifted by approximately 0.4 V in the positive direction in each case relative to the "parent" bispicen and tmpa complexes. The fully oxidized form of complex 5 has been shown to act as a two-electron electrocatalytic oxidant, selectively oxidizing benzyl alcohol to benzaldehyde.