Electronic Structures of Homoleptic [Tris(2,2′-bipyridine)M]n Complexes of the Early Transition Metals (M = Sc, Y, Ti, Zr, Hf, V, Nb, Ta; n=1+, 0, 1-, 2-, 3-): An Experimental and Density Functional Theoretical Study
Electronic Structures of Homoleptic [Tris(2,2′-bipyridine)M]n Complexes of the Early Transition Metals (M = Sc, Y, Ti, Zr, Hf, V, Nb, Ta; n=1+, 0, 1-, 2-, 3-): An Experimental and Density Functional Theoretical Study
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DOI：
10.1021/ic302799s
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发表时间：
2013-02-18
影响因子：
4.6
通讯作者：
Wieghardt, Karl
中科院分区：
文献类型：
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作者：
Bowman, Amanda C.;England, Jason;Wieghardt, Karl
配合物[M（（t）bpy）（3）]（0，1）的电子结构.（M = Nb，To;（t）bpy = 4，4 '-二叔丁基-2，2'-联吡啶）的合成。并测定了[Na（THF）（5）][Ta（（t）bpy）（3）]的晶体结构。这些研究由密度泛函理论（DFT）补充，并且计算扩展到包括系列[Y（bpy）（3）]（m）（m = 0，1-，2-，3-）、[Ti（bpy）（3）]（n）（n = 1+，0，1-，2-，3-）、[Zr（bpy）（3）]（p）和[Hf（bpy）（3）]（P）（p = 0，1-，2-）。这使我们能够确定这些早期过渡金属三（2，2 '-联吡啶）配合物的正确电子结构。结果表明，在[Y（bpy）（3）]（m）系列中，中心离子具有一个不变的+III氧化态，组成该系列的三个连续的单电子氧化还原过程完全是基于配体的，产生三个（bpy（.））（一）。中性络合物中的自由基阴离子到三阴离子中的三个抗磁性二价阴离子（bpy（2-））（2-）。对于[Ti（bpy）（3）]（n）系列也是如此，其中中性配合物含有3（bpy（.））(1-)和三价阴离子3（bpy（2-））（2-）阴离子。因此，中心离子总是具有中心Ti-III（d（1））离子，其分子内反铁磁耦合到任何（bpy（.））(1-)配体存在。相比之下，[Zr（bpy）（3）]（P）和[Hf（bpy）（3）]（P）系列中的中心金属离子总是具有+IV氧化态;因此，二价阴离子含有三个（bpy（2.））(2-)配体并产生S = 0基态。具有S = 1/2基态的中性Nb和Ta类似物的电子结构最好描述为[Nb-IV（bpy（2-））（2）（bpy）（0））]（0）和[Ta-V（bpr）（bpy（2-））（2）]（0），它们的S = 0单阴离子为[Nb-IV（bpy（.））（bpy（2-））（2）]（1-）和[Ta-V（bpy（2-））（3）]（1-）。Nb系列中的中心金属离子保持+IV氧化态，而Ta系列中的中心金属离子始终显示+V氧化态。
The electronic structures of the complexes [M((t)bpy)(3)](0,1). (M = Nb, To; (t)bpy = 4,4'-di-tert-butyl-2,2'-bipyridine) have been investigated using a combination of UV-vis spectroscopy, EPR spectroscopy, and XAS. Furthermore, the crystal structure of [Na(THF)(5)][Ta((t)bpy)(3)] has been determined. These studies were supplemented by density functional theory (DFT) and the calculations extended to include the series [Y(bpy)(3)](m) (m = 0, 1-, 2-, 3-), [Ti(bpy)(3)](n) (n = 1+, 0, 1-, 2-, 3-), [Zr(bpy)(3)](p), and [Hf(bpy)(3)](P) (p = 0, 1-, 2-). This has allowed us to define the correct electronic structures of these early transition metal tris(2,2'-bipyridine) complexes. It is shown that in the [Y(bpy)(3)](m) series the central ion possesses an invariant +III oxidation state and that the three successive one-electron redox processes that comprise the series are solely ligand-based, yielding three (bpy(.))(I). radical anions in the neutral complex through to three diamagnetic dianions (bpy(2-))(2-) in the trianion. The same is true for the [Ti(bpy)(3)](n) series where the neutral complex contains 3(bpy(.))(1-) and the trianion 3(bpy(2-))(2-) anions. Hence, the central ion always possesses a central Ti-III (d(1)) ion that intramolecularly antiferromagnetically couples to any (bpy(.))(1-) ligands present. In contrast, the central metal ions in the series [Zr(bpy)(3)](P) and [Hf(bpy)(3)](p) always possess a +IV oxidation state; hence, the dianions contain three (bpy(2.))(2-) ligands and yield an S = 0 ground state. The electronic structures of the neutral Nb and Ta analogues possessing S = 1/2 ground states are best described as [Nb-IV(bpy(2-))(2)(bpy)(0))](0) and [Ta-V(bpr)(bpy(2-))(2)](0), and their S = 0 monoanions as [Nb-IV(bpy(.))(bpy(2-))(2)](1-) and [Ta-V(bpy(2-))(3)](1-). The central metal ion in the Nb series maintains a +IV oxidation state, while in the Ta series the central metal ion displays a +V oxidation state throughout.