Pejov Ljupco, Jovanovski Gligor, Grupce Orhideja, Soptrajanov Bojan
Institut za hemija, PMF, Univerzitet "Sv. Kiril i Metodij", PO Box 162, 1001 Skopje, Macedonia.
Spectrochim Acta A Mol Biomol Spectrosc. 2007 Feb;66(2):419-26. doi: 10.1016/j.saa.2006.03.016. Epub 2006 Mar 22.
On the basis of the experimentally obtained frequencies of isotopically isolated OH and OD species, the anharmonicity constants, as well as the harmonic eigenvalues of the OH and OD stretching vibrations for two members of the isomorphous series of metal(II) saccharinates hexahydrates (those of Mn and Cu) were calculated using several theoretical models [B. Berglund, J. Lindgren, J. Tegenfeldt, J. Mol. Struct. 43 (1978) 169, M.G. Sceats, S.A. Rice, J. Chem. Phys. 71 (1979) 973, H. Engstrom, J.B. Bates, L.A. Boatner, J. Chem. Phys. 73 (1980) 1073]. The anharmonicity constants and the nu(OH)/nu(OD) isotopic ratios correlate well with the stretching frequencies of the isotopically isolated OH and OD oscillators. Both anharmonicity constants and isotopic ratios as criteria for the anharmonicity of the OH (OD) vibrations show that, with a very few exceptions, it increases with the increase in the hydrogen bond strength. The exceptions from the trend are explained in terms of local electrostatic field differences and force constant changes due to the coordination to the metal ion. The obtained regression equations were used to predict the anharmonicity constants of the nu(OD) modes in other members of the series. Within the three-particle model of the hydrogen bonded complex, the parameters characterising the coupling of the nu(OH)/nu(OD)/modes with the low-frequency nu(Ocdots, three dots, centeredO) ones were estimated. The positions of the overtones of OH and OD stretching vibrations in the compounds of copper and manganese were estimated using the calculated anharmonicity parameters. The predicted values for the OD oscillators were compared with the experimentally obtained data. Model calculations of the described type are shown to be valuable in the assignment of the second-order transitions, especially in complex systems.
基于实验获得的同位素分离的OH和OD物种的频率，使用几种理论模型[B. Berglund, J. Lindgren, J. Tegenfeldt, J. Mol. Struct. 43 (1978) 169, M.G. Sceats, S.A. Rice, J. Chem. Phys. 71 (1979) 973, H. Engstrom, J.B. Bates, L.A. Boatner, J. Chem. Phys. 73 (1980) 1073]计算了六水合金属（II）糖精同构系列的两个成员（锰和铜的六水合物）中OH和OD伸缩振动的非谐性常数以及谐振动本征值。OH和OD伸缩振动的非谐性常数以及ν(OH)/ν(OD)同位素比与同位素分离的OH和OD振子的伸缩频率具有良好的相关性。作为OH（OD）振动非谐性判据的非谐性常数和同位素比均表明，除极少数例外情况外，其随氢键强度的增加而增大。该趋势的例外情况可根据局部静电场差异以及与金属离子配位导致的力常数变化来解释。所得到的回归方程用于预测该系列其他成员中ν(OD)模式的非谐性常数。在氢键复合物的三粒子模型中，估算了表征ν(OH)/ν(OD)模式与低频ν(O···O)模式耦合的参数。利用计算得到的非谐性参数估算了铜和锰化合物中OH和OD伸缩振动倍频的位置。将OD振子的预测值与实验获得的数据进行了比较。结果表明，所述类型的模型计算在二阶跃迁的归属中具有重要价值，尤其是在复杂体系中。
