Electronic Structures of Cr(III) and V(II) Polypyridyl Systems: Undertones in an Isoelectronic Analogy
Electronic Structures of Cr(III) and V(II) Polypyridyl Systems: Undertones in an Isoelectronic Analogy
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DOI：
10.1021/acs.inorgchem.1c01129
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发表时间：
2021-08-12
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.
最近报道的关于V2+多吡啶体系的光物理性质的描述强调了2，2‘-联吡啶(BPY)和1，10-邻菲咯啉(Phen)的等电子、d(3)、Cr3+和V2+三同型多吡啶配合物之间的一些区别。在这里，我们结合理论和实验数据来解释电子结构上的差异。我们首次报道了V~(2+)配合物[V(Bpy)(3)](BPh_4)(2)(V-1B)和[V(Phen)(3)](OTf)(2)(V~(2))的晶体结构，并观察到相对于类似的Cr3+络合物有明显的三角扭曲。我们使用电子吸收光谱结合TD-DFT计算来指定V-1B和V-2的金属-配体电荷转移(MLCT)性质，这些性质是仅在Cr3+类似物中观察到的配位内和跃迁(4)((IL)-I-3)所独有的。我们新开发的自然跃迁自旋密度(NT Rho(α，β))图表征了Cr3+和V2+的吸收特性。密度泛函的多重决定方法指定了通过电子离域稳定的V-1B的E-2态的能量。我们发现，Cr3+和V2+多吡啶在激发态寿命上的巨大差异源于它们最低双重态的性质和系间交叉途径的不同，这两者都源于三角结构的扭曲和金属-配体的pi共价。
A recently reported description of the photophysical properties of V2+ polypyridyl systems has highlighted several distinctions between isoelectronic, d(3), Cr3+, and V2+ tris-homoleptic polypyridyl complexes of 2,2'-bipyridine (bpy) and 1,10-phenanthroline (phen). Here, we combine theory and experimental data to elucidate the differences in electronic structures. We provide the first crystallographic structures of the V2+ complexes [V(bpy)(3)](BPh4)(2) (V-1B) and [V(phen)(3)](OTf)(2) (V-2) and observe pronounced trigonal distortion relative to analogous Cr3+ complexes. We use electronic absorption spectroscopy in tandem with TD-DFT computations to assign metal-ligand charge transfer (MLCT) properties of V-1B and V-2 that are unique from the intraligand transitions, (4)((IL)-I-3), solely observed in Cr3+ analogues. Our newly developed natural transition spin density (NT rho(alpha,beta)) plots characterize both the Cr3+ and V2+ absorbance properties. A multideterminant approach to DFT assigns the energy of the E-2 state of V-1B as stabilized through electron delocalization. We find that the profound differences in excited state lifetimes for Cr3+ and V2+ polypyridyls arise from differences in the characters of their lowest doublet states and pathways for intersystem crossing, both of which stem from trigonal structural distortion and metal-ligand pi-covalency.