Brown I David
Brockhouse Institute for Materials Research, McMaster University, Hamilton, Ontario, Canada L8S 4M1.
Acta Crystallogr B. 2009 Dec;65(Pt 6):684-93. doi: 10.1107/S0108768109034417. Epub 2009 Oct 27.
The differences between Wang and Liebau's [Wang & Liebau (2007). Acta Cryst. B63, 216-228] stoichiometric valence (atomic valence) and structural valence (bond-valence sum) observed in Sn(2+) and other lone-pair cation oxycomplexes arises from their use of the Brese & O'Keeffe bond-valence parameters which are based on the assumption that the bond-valence parameter b = 0.37 A applies to all bond types. According to the theory of the bond-valence model, the bond-valence sum is necessarily equal to the ionic charge, implying that in the Wang and Liebau model the ionic charges are equal to the structural valence. If charges are chosen equal to the stoichiometric valence, the bond-valence parameters for Sn(2+)-O bonds are R(0) = 1.859 A, b = 0.55 A. While both models are theoretically valid, only the standard model relates bond valences to the concept of atomic valence. Wang and Liebau's suggestion that cation-lone-pair bonds make a significant contribution to the valence sums is confirmed, but such bonds cannot account for the full difference between the stoichiometric and structural valences because they are present in only a few compounds.
王和利鲍[Wang & Liebau (2007). Acta Cryst. B63, 216 - 228]在Sn(2+)及其他孤对阳离子氧配合物中观察到的化学计量价（原子价）和结构价（键价和）之间的差异，源于他们使用了布雷泽和奥基夫的键价参数，这些参数基于键价参数b = 0.37 Å适用于所有键型的假设。根据键价模型理论，键价和必然等于离子电荷，这意味着在王和利鲍模型中离子电荷等于结构价。如果电荷取值等于化学计量价，Sn(2+) - O键的键价参数为R(0) = 1.859 Å，b = 0.55 Å。虽然这两种模型在理论上都是有效的，但只有标准模型将键价与原子价的概念联系起来。王和利鲍提出的阳离子孤对键对价和有显著贡献的观点得到了证实，但这种键不能解释化学计量价和结构价之间的全部差异，因为它们仅存在于少数化合物中。
