The competition between halogen bonds (Br⋯O) and C–H⋯O hydrogen bonds: the structure of the acetone–bromine complex revisited
The competition between halogen bonds (Br⋯O) and C–H⋯O hydrogen bonds: the structure of the acetone–bromine complex revisited
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卤素键（Br⋯O）和C-H⋯O氢键之间的竞争：丙酮-溴配合物结构的再探讨
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发表时间：
2013
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通讯作者：
M. Pitak
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作者：
Richard H. Jones;K. Knight;W. G. Marshall;S. Coles;P. Horton;M. Pitak
用单晶X射线(在110和200K)和高分辨中子粉末衍射(仅在110K)相结合的方法重新确定了著名的丙酮-Br2络合物的晶体结构。结果表明，羰基氧与最近的溴原子之间发生了显著的相互作用，导致了分子中溴-溴键的显著延长。在早先被广泛引用的晶体结构中，没有这种伸长的报道。此外，新结构表明存在额外的较弱的C-H⋯O和C-H⋯BR相互作用。在这个简单的络合物中，卤素键比氢键(C-H⋯O)更强，前者的相互作用发生在靠近(~12°)羰基平面的地方，C-H⋯BR补充了更强的卤键。
A combination of single-crystal X-ray (at 110 and 200 K) and high-resolution neutron powder diffraction (110 K only) using perdeuterated samples has been used to re-determine the crystal structure of the well-known acetone–Br2 complex. The results indicate a significant interaction between the carbonyl oxygen and the nearest Br atom leading to a marked elongation of the molecular Br–Br bond. In the earlier widely cited crystal structure, no such elongation was reported. Furthermore, the new structure indicates the presence of additional weaker C–H⋯O and C–H⋯Br interactions. In this simple complex, in which the halogen bonding is strong compared to the hydrogen bonding (C–H⋯O), the former interaction is found to occur close (~12°) to the plane of the carbonyl group, with the C–H⋯Br complementing the stronger halogen bond.