Xue Junhui, Jiang Ye, Li Weihong, Yang Limin, Xu Yizhuang, Zhao Guozhong, Zhang Gaohui, Bu Xiaoxia, Liu Kexin, Chen Jia'er, Wu Jinguang
Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China; Department of Chemistry, Renmin University of China, Beijing 100872, China.
Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.
Spectrochim Acta A Mol Biomol Spectrosc. 2015 Feb 25;137:864-70. doi: 10.1016/j.saa.2014.09.030. Epub 2014 Sep 22.
The coordination structures formed by calcium complexes with nicotinamide (na), isonicotinamide (ina) and picolinamide (pa) and praseodymium bromide-na are reported. The structures of CaCl2·(C6H6N2O)2·2H2O (Ca-na), CaCl2·(C6H6N2O)2·4H2O (Ca-ina), CaCl2·(C6H6N2O)2·5H2O (Ca-pa) and PrBr3·(C6H6N2O)2·6H2O (PrBr-na) in the solid state have been characterized by X-ray single crystal diffraction, FTIR, FIR, THz and Raman spectroscopies. Carbonyl oxygen of nicotinamide is coordinated to Ca(2+), but it is O-monodentate (carbonyl oxygen) and N,O-bidentate ligand (pyridyl nitrogen and carbonyl oxygen) for Pr(3+) to form a chain structure in PrBr-na. For isonicotinamide, only carbonyl oxygen atom is coordinated to Ca(2+). Pyridyl nitrogen and carbonyl oxygen of picolinamide are coordinated to Ca(2+) to form a five-membered ring structure. The crystal structure and spectroscopic results indicate the differences of the coordination of Ca and Pr ions, the changes of hydrogen bonds and conformation of the ligands induced by complexation. Unlike transition metal ions, Sr(2+) or lanthanide ions, Ca(2+) is inclined to coordinate to carbonyl oxygen atoms of the ligands.
报道了钙与烟酰胺（na）、异烟酰胺（ina）和吡啶甲酰胺（pa）形成的配合物以及溴化镨 - na形成的配位结构。通过X射线单晶衍射、傅里叶变换红外光谱（FTIR）、远红外光谱（FIR）、太赫兹光谱和拉曼光谱对固态的CaCl₂·(C₆H₆N₂O)₂·2H₂O（Ca - na）、CaCl₂·(C₆H₆N₂O)₂·4H₂O（Ca - ina）、CaCl₂·(C₆H₆N₂O)₂·5H₂O（Ca - pa）和PrBr₃·(C₆H₆N₂O)₂·6H₂O（PrBr - na）进行了表征。烟酰胺的羰基氧与Ca(2+)配位，但对于Pr(3+)而言，它是O - 单齿（羰基氧）和N,O - 双齿配体（吡啶氮和羰基氧），在PrBr - na中形成链状结构。对于异烟酰胺，只有羰基氧原子与Ca(2+)配位。吡啶甲酰胺的吡啶氮和羰基氧与Ca(2+)配位形成五元环结构。晶体结构和光谱结果表明了Ca和Pr离子配位情况的差异、氢键的变化以及络合作用引起的配体构象变化。与过渡金属离子、Sr(2+)或镧系离子不同，Ca(2+)倾向于与配体的羰基氧原子配位。
