A new supramolecular compound of chrome(III): Synthesis, spectroscopic characterization, X-ray crystal structure, DFT, and solution studies

• Published in: Journal of molecular structure 2010-06, Vol.973 (1), p.1-8
• Main Authors: Eshtiagh-Hosseini, Hossein, Yousefi, Zakieh, Mirzaei, Masoud, Chen, Ya-Guang, Ali Beyramabadi, S., Shokrollahi, Ardeshir, Aghaei, Roghayyeh
• Format: Article
• Language: English
• Subjects: 2-Aminopyrimidine; Chrome; Crystal structure; Crystallography; DFT; Ligands; Pyridine-2,6-dicarboxylic acid; Solid state; Solution studies; Spectroscopy; Stoichiometry; Supramolecular compounds; X-rays
• ISSN: 0022-2860; 1872-8014
• DOI: 10.1016/j.molstruc.2010.02.054

A new supramolecular compound of Cr(III) atom was synthesized and characterized by using elemental analysis, FTIR spectroscopy, UV–vis, and single crystal X-ray diffraction method. The chemical formula and space group of the resulting compound is (2-apymH)[Cr(pydc) 2]·2H 2O ( 1) (pydc = 2,6-pyridinedicarboxylate, 2-apym = 2-aminopyrimidine) and P2 1/ c where the final R value is 0.0157 for 3896 reflections collected. The [Cr(pydc) 2] − anions and the (2-apymH) + moiety form a three-dimensional solid state structure by a variety of noncovalent interactions such as ion pairing and hydrogen bonds interactions. On the basis of crystallographic data, it can be seen that Cr(III) atom is six-coordinated by two (pydc) 2− groups. With respect to bond lengths and angles, it is observed that coordination sphere around Cr(III) atom is a distorted octahedral. Furthermore, DFT calculation and solution study have been completely performed on 1 where corresponding data showed that obtained results from DFT and solution studies have good agreement with X-ray crystallography results. The optimized geometry confirms that the C–O (bonded) bond length of (pydc) 2− ligand in its complex form has been increased compared with the free ligand. The evidence shows that C–O (bonded) is weakened upon formation of complex, while C O (free) converted to double bond. Anionic complex possesses 90 occupied molecular orbitals and 3 half-occupied ones (91–93). A comparison between the stoichiometry of the crystalline complex in pydcH 2–2-apym–Cr system and the results obtained from solution studies clearly revealed that the CrL 2QH is the most abundant species existing in aqueous solution possesses a stoichiometry similar to that of the complex which was obtained in the solid state.