Narrow Results

The original length d₀ of N—H and H⋯O bonds in various inorganic systems was comprehensively studied from a chemical bond viewpoint. Two linear relationships between d₀ and the average bond lengths of each system, d_{0, N-H}, versus and d_{0, H⋯O} versus were respectively established. It is indicated that d₀ is affected by the crystalline environment evidently, therefore, the valence electron distribution of hydrogen atom which depends on the lengthening degree of the original bond length is strongly affected by the chemical environment of hydrogen atoms. The obtained valence electron distributions of hydrogen are in a good agreement with the bond valence sum rule, and their overall applicability to ammonium ion interactions was discussed.

From the chemical bond viewpoint, the microscopic characterstatics of hydrogen bonds in M_i—OH₂⋯O (M is the metal cation coordinated to water molecule and i is the number of M) systems were comprehensively studied. It is shown that the original O—OH and H⋯O bond lengths of each hydrogen bonding system are evidently influenced by the crystalline environment and strongly dependent on the corresponding average bond lengths of each system, and . Furthermore, the hydrogen bonding capability of water molecules coordinated to various metal cations was properly estimated and found to be related to the ionic electronegativities of these metal cations. The current work provides a useful route to calculating hydrogen bond valences within reasonable accuracy and sheds light on the rational utilization of hydrogen bonds in crystal design.