Doublet Ground State in a Vanadium(II) Complex: Redox and Coordinative Noninnocence of Tripodal Ligand Architecture
Doublet Ground State in a Vanadium(II) Complex: Redox and Coordinative Noninnocence of Tripodal Ligand Architecture
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DOI：
10.1021/acs.inorgchem.1c03418
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发表时间：
2022-05-02
影响因子：
4.6
通讯作者：
Shores, Matthew P.
中科院分区：
文献类型：
--
作者：
Joyce, Justin P.;Portillo, Romeo, I;Shores, Matthew P.
我们报道了一系列V ~（2+）/~（3+）Tren桥连的亚氨基吡啶配合物[Tren =三（2-氨乙基）胺]的几何和电子结构，这些配合物使我们能够观察到一个名义上为3d ~ 3的物质的一个意想不到的双重基态。Tren与吡啶甲醛或甲基-6-甲酰烟酸酯发生缩合反应，形成相应的三脚架配体组（py）3 tren和（5-CO2 Me）3 tren。（py）3 tren配体分别与V2+和V3+金属中心配位形成络合盐[1-H]（OTf）2和[1-H]（OTf）3（OTf-= CF 3SO 3-），[1-H]2+与V2+（3d 3）和亚氨基吡啶配体的π共价性减弱了其电子排斥作用。对于[1-H]3+，tren支架的桥头氮与V3+（3d 2）金属中心形成第七配位共价键。（5-CO2 Me）3 tren与V2+金属中心配位，得到了具有双重基态（S=1/2）的七配位化合物[1-CO2 Me]（OTf）2。配合物的单晶X-射线衍射，电子吸收，和电化学实验的特点是一致的，并通过计算技术证实了电子结构。我们提出了一种新的计算程序，我们称之为自旋优化近似对（SOAP）方法，使电子-电子相互作用的可视化和量化。
We report on the geometric and electronic structures of a series of V2+/3+tren-bridged iminopyridine complexes [tren =tris(2-aminoethyl)amine] that enable the observation of anunexpected doublet ground state for a nominally 3d3species. Trenundergoes condensation reactions with picolinaldehyde or methyl-6-formylnictonate to form the respective tripodal ligand sets of(py)3tren and (5-CO2Mepy)3tren. The (py)3tren ligand iscoordinated to V2+and V3+metal centers to form complex salts[1-H](OTf)2and[1-H](OTf)3, respectively (OTf-=CF3SO3-).For[1-H]2+, strong metal-ligand pi-covalency with respect to theV2+(3d3) and iminopyridine ligands weakens its interelectronicrepulsion. For[1-H]3+, the bridgehead nitrogen of the tren scaffoldforms a seventh coordinate covalent bond with a V3+(3d2) metalcenter. The coordination of (5-CO2Mepy)3tren to a V2+metal center results in the redox noninnocent and heptacoordinatecompound[1-CO2Me](OTf)2with a doublet (S=1/2) ground state that we support with magnetic susceptibility and spectroscopymeasurements. The complexes are uniformly characterized experimentally with single-crystal X-ray diffraction, electronic absorbance,and electrochemistry, and electronic structures are corroborated by computational techniques. We present a new computationalprocedure that we term the spin-optimized approximate pair (SOAP) method that enables the visualization and quantification of electron-electron interactions.