Family of Cofacial Bimetallic Complexes of a Hexaanionic Carboxamide Cryptand
Family of Cofacial Bimetallic Complexes of a Hexaanionic Carboxamide Cryptand
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DOI：
10.1021/ic200143b
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发表时间：
2011-05-02
影响因子：
4.6
通讯作者：
Nocera, Daniel G.
中科院分区：
文献类型：
--
作者：
Alliger, Glen E.;Mueller, Peter;Nocera, Daniel G.
已经制备了一系列配位化合物，包括锰、铁、镍和锌，由六阴离子隐式结合，其中羧胺是阴离子n给体。金属配合物的x射线晶体学研究表明，金属中心呈三角形单锥体形状，金属间距离d(Mn,avg) = 6.080埃至d(Ni,avg) = 6.495埃。所有具有三角单锥体金属(U)离子的配合物都在Cc中结晶，并且具有由桥接钾反阳离子连接的隐阴离子组成的扩展的三维网络。我们还报道了自由隐体配体的第一个固态结构，其腔中没有客体，具有扩展的氢键网络。金属配合物的磁强计数据显示金属中心的弱反铁磁耦合。只有二铁（II）配合物表现出可逆的电化学反应，相应地，它的化学氧化产生了一种粉末，称为二铁（III）同系物。将氰化物插入到二铁（II）配合物的金属间间隙中，并将其固态结构与最近报道的二钴（II）类似物进行了比较。二铁(H)和二钴（II）中心之间的反铁磁耦合在氰化物桥接后与未桥接的同系物相比没有显著增加。单位点模型可以很好地拟合未桥接的二铁（II）和二铁（II）配合物的穆斯堡尔光谱，而对氰化物桥接的二铁（II）中心则需要两个位点的拟合。
A series of coordination compounds has been prepared comprising manganese, iron, nickel, and zinc bound by a hexaanionic cryptand where carboxamides are anionic N-donors. The metal complexes have been investigated by X-ray crystallography, and possess metal centers in trigonal monopyramidal geometries with inter:metallic distances spanning d(Mn,avg) = 6.080 angstrom to d(Ni,avg) = 6.495 angstrom. All complexes featuring trigonal monopyramidal metal(U) ions crystallize in Cc, and feature extended three-dimensional networks composed of cryptate anions linked by bridging potassium countercations. We also report the first solid state structure of the free cryptand ligand, which features no guest in its cavity and which possesses an extended hydrogen-bonding network SQuID magnetometry data of the metal complexes reveal weak antiferromagnetic coupling of the metal centers. Only the diiron(II) complex exhibits reversible electrochemistry, and correspondingly, its chemical oxidation yields a powder formulated as the diiron(III) congener. The insertion of cyanide into the intermetallic cleft of the diiron(II) complex has been achieved, and comparisons of its solid state structure to the recently reported dicobalt(II) analogue are made. The antiferromagnetic coupling between the diiron(H) and the dicobalt(II) centers when bridged by cyanide does not increase significantly relative to the unbridged congeners. A one-site model satisfactorily fits Mossbauer spectra of unbridged diiron(II) and diiron(II) complexes whereas a two site fit was needed to model the iron(II) centers that are bridged by cyanide.