Koleva Violeta G
Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Akad. G. Bonchev St, bl.11, 1113 Sofia, Bulgaria.
Spectrochim Acta A Mol Biomol Spectrosc. 2005 Dec;62(4-5):1196-202. doi: 10.1016/j.saa.2005.04.025. Epub 2005 Jun 20.
The vibrational behavior of the uncoupled nu(OD) modes and of the water librations in dittmarite-type compounds M'M''PO4.H2O (M'=K+, NH4+; M''=Mn2+, Co2+, Ni2+) is analyzed in terms of the influence of two types of metal-water interactions (M+-H2O and M2+-H2O), the hydrogen bonding and the repulsion potential of the lattices. The M+-H2O interaction is found to be the main factor, which influences nuOD. The strong K+-H2O interaction weakens in a higher degree the intramolecular O-H bonds than the corresponding M2+-H2O interactions (M2+=Mn, Co, Ni). As a result nuOD is shifted to lower wavenumbers in the potassium series than in ammonium one, irrespective of the synergetic effect of M2+, the hydrogen bond lengths and the repulsion potential of the lattices. The analysis of the spectroscopic data evidences for the dominating influence of the M2+-H2O interaction on the wagging mode. The blue shift of nuwag strictly follows the increasing synergetic effect of M2+, i.e. nuM'/Mn<nuM'/Co<nuM'/Ni, in all cases, irrespective of the strength of the M+-H2O interactions, the hydrogen bond lengths and the higher repulsion potential of the K-lattices. The rocking mode is insensitive to the replacement of the M2+ ions. Some relations between the spectroscopic and structural data are given.
根据两种类型的金属 - 水相互作用（M⁺ - H₂O和M²⁺ - H₂O）、氢键以及晶格的排斥势的影响，分析了迪特马利特型化合物M'M''PO₄·H₂O（M' = K⁺，NH₄⁺；M'' = Mn²⁺，Co²⁺，Ni²⁺）中未耦合的ν(OD)模式和水的平动的振动行为。发现M⁺ - H₂O相互作用是影响νOD的主要因素。与相应的M²⁺ - H₂O相互作用（M²⁺ = Mn、Co、Ni）相比，强K⁺ - H₂O相互作用在更大程度上削弱了分子内的O - H键。因此，无论M²⁺的协同效应、氢键长度和晶格的排斥势如何，钾系列中的νOD都比铵系列中的向更低波数移动。光谱数据分析表明M²⁺ - H₂O相互作用对摇摆模式有主导影响。在所有情况下，无论M⁺ - H₂O相互作用的强度、氢键长度以及K晶格的较高排斥势如何，νwag的蓝移都严格遵循M²⁺协同效应的增加，即νM'/Mn < νM'/Co < νM'/Ni。摇摆模式对M²⁺离子的取代不敏感。给出了光谱数据和结构数据之间的一些关系。
