Uncommon cis configuration of a metal-metal bridging noninnocent Nindigo ligand.
Uncommon cis configuration of a metal-metal bridging noninnocent Nindigo ligand.
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DOI：
10.1021/ic501460d
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发表时间：
2014-08
影响因子：
4.6
通讯作者：
P. Mondal;Sebastian Plebst;Ritwika Ray;S. Mobin;W. Kaim;G. K. Lahiri
中科院分区：
文献类型：
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作者：
P. Mondal;Sebastian Plebst;Ritwika Ray;S. Mobin;W. Kaim;G. K. Lahiri
与已报道的几种反式NIndigo配体的配位化合物[NIndigo=Indigo-双(N-芳亚胺)=LH2]不同，新的二Ru配合物[(Acac)2Ru(μ，η(2)：η(2)-L)Ru(Bpy)2](2+)=2(2+)在第一个文献报道的NIndigo配体不对称桥联的顺式构型[L(2-)=Indigo-双(N-苯基亚胺)阴离子]中显示出共享边的五元和七元螯合环。化合物[2](ClO_4)_2具有一个Ru(α-diimine)3位和一个Ru中心，并带有三个带负电荷的螯合配体。化合物[2](ClO4)2是由含[Ru(Bpy)2](2+)的顺式前驱体[(Lh)Ru(Bpy)2]ClO4=[1]ClO4合成的，阳离子中存在分子内氢键。根据X射线结构、电子顺磁共振和紫外可见近红外光谱电化学，结合密度泛函理论计算结果，分别表征了1(N)和2(N)氧化还原系列中金属或配体为中心的电子转移的四个可及氧化态。Ru(III)/Ru(II)体系2(2+)的结构不对称性反映在电子不对称性(I类混价状态)上，使得非无害的NIndigo桥成为主要的氧化还原活性中心。
In contrast to several reported coordination compounds of trans-Nindigo ligands [Nindigo = indigo-bis(N-arylimine) = LH2] with one or two six-membered chelate rings involving one indole N and one extracyclic N for metal binding, the new diruthenium complex ion [(acac)2Ru(μ,η(2):η(2)-L)Ru(bpy)2](2+) = 2(2+) exhibits edge-sharing five- and seven-membered chelate rings in the first documented case of asymmetric bridging by a Nindigo ligand in the cis configuration [L(2-) = indigo-bis(N-phenylimine)dianion]. The dication in compound [2](ClO4)2 displays one Ru(α-diimine)3 site and one ruthenium center with three negatively charged chelate ligands. Compound [2](ClO4)2 is obtained from the [Ru(bpy)2](2+)-containing cis precursor [(LH)Ru(bpy)2]ClO4 = [1]ClO4, which exhibits intramolecular H-bonding in the cation. Four accessible oxidation states each were characterized for the 1(n) and 2(n) redox series with respect to metal- or ligand-centered electron transfer, based on X-ray structures, electron paramagnetic resonance, and ultraviolet-visible-near-infrared spectroelectrochemistry in conjunction with density functional theory calculation results. The structural asymmetry in the Ru(III)/Ru(II) system 2(2+) is reflected by the electronic asymmetry (class I mixed-valence situation), leaving the noninnocent Nindigo bridge as the main redox-active site.