Molecular and Electronic Structures of Six-Coordinate 鈥淟ow-Valent鈥?[M(Mebpy)3]0 (M = Ti, V, Cr, Mo) and [M(tpy)2]0 (M = Ti, V, Cr), and Seven-Coo
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- 作者：Mei Wang ; Thomas Weyherm眉ller ; Jason England ; Karl Wieghardt
- 刊名：Inorganic Chemistry
- 出版年：2013
- 出版时间：November 4, 2013
- 年：2013
- 卷：52
- 期：21
- 页码：12763-12776
- 全文大小：708K
- 年卷期：v.52,no.21(November 4, 2013)
- ISSN：1520-510X
文摘
The electronic structures of a series of so-called 鈥渓ow-valent鈥?transition metal complexes [M(Mebpy)3]0 and [M(tpy)2]0 (Mebpy = 4,4鈥?dimethyl-2,2鈥?bipyridine and tpy = 2,2鈥?6鈥?2鈥?terpyridine) have been determined using a combination of X-ray crystallography, magnetochemistry, and UV鈥搗is鈥揘IR spectroscopy. More specifically, the crystal structures of the long-known complexes [TiIV(tpy2鈥?/sup>)2]0 (S = 0, 6), [VIV(tpy2鈥?/sup>)2] (S = 1/2, 7), [TiIII(Mebpy鈥?/sup>)3]0 (S = 0, 1), [VII(Mebpy鈥?/sup>)2(Mebpy0)]0 (S = 1/2, 2), and [MoIII(Mebpy鈥?/sup>)3]0 (S = 0, 4) have been determined for the first time. In all cases, the experimental results confirm the electronic structure assignments that we ourselves have recently proposed. Additionally, the six-coordinate complex [MoIII(bpy0)2Cl2]Cl路2.5CH3OH (S = 3/2, 13), and seven-coordinate species [MoIVF(Mebpy鈥?/sup>)2(Mebpy0)](PF6) (S = 0, 5), [MoIVCl(tpy鈥?/sup>)2](PF6)路CH2Cl2 (S = 0, 11), and [WVF(tpy鈥?/sup>)(tpy2鈥?/sup>)](PF6)路CH2Cl2 (S = 0, 12) have been synthesized and, for the first time, crystallographically characterized. Using the resulting data, plus that from previously published high-resolution X-ray structures of analogous compounds, it is shown that there is a linear correlation between the average Cpy鈥揅鈥?sub>py bond distances in these complexes and the total charge (n) of the ligands, {(bpy)3}n and {(tpy)2}n. Hence, an assignment of the total charge of coordinated bpy or tpy ligands and, by extension, the oxidation state of the central metal ion can reliably be made on the basis of X-ray crystallography alone. In this study, the oxidation states of the metal ions range from +II to +V and in no case has an oxidation state of zero been validated. It is, therefore, highly misleading to use the term 鈥渓ow-valent鈥?to describe any of the aforementioned neutral complexes.