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Abstract: The title compound, N,N′-di(2-methoxyphenyl)formamidine (DMPF) was synthesized and characterized byFT-IR, FT-Raman, 1H NMR, 13C NMR spectroscopy and X-ray single crystal diffraction. The results show that the compound crystallizes in anorthorhombic system, with space group of Pbca and eight molecules in the unit cell. The unit cell parameters are: a =11.1118 (7)Å, b =14.9878 (9)Å and c =16.2851 (10)Å. The molecular geometry, the normal mode frequencies and corresponding vibrational assignments of DMPF at the ground state were performed by HF and B3LYP methods with 6-311+G(d,p) basis set. It was observed that the bond lengths and angles in the molecule, obtained by X-ray at the level of theory, were in good agreement with those of the experiment. A detailed interpretation of the infrared and Raman spectra of DMPF was reported. The 13C NMR and 1H NMR of DMPF have been calculated usingHF and B3LYP methods with 6-311+G(d,p) basis set. Comparison between experimental and theoretical results showed that B3LYP/6-311+G(d,p) method is able to provide more satisfactory results for predicting IR, Raman, 1H NMR and 13C NMR properties. [Copyright &y& Elsevier]

Two nickel(II) supramolecular compounds [Ni(H 2 O) 6 ](4-apyH) 2 [Ni(2,6-pydc) 2 ] 2 ·4H 2 O·2EtOH ( 1 ) and [Ni(2,3-pydcH) 2 ·2H 2 O] ( 2 ) (where 4-apy = 4-aminopyridine, 2,3-pydcH 2 = 2,3-pyridinedicarboxylic acid and 2,6-pydcH 2 = 2,6-pyridinedicarboxylic acid) were structurally compared in their solid state and solution forms. While the 2,6-pydc ligand in compound 1 uses both its carboxylate groups for coordination to nickel(II), the 2,3-pydc ligand in compound 2 binds through only one of the carboxylate groups, and the second carboxylate group which is expected to bind to another Ni(II) atom, does not coordinate to the metal. Using molecular dynamics simulations, it was shown that differences in ligands’ binding affinities could be correlated to different behaviors and interactions during proton-transfer assembly of these ligands. [ABSTRACT FROM AUTHOR]

The three complexes [Zn(pyc)(HO)]·HO ( 1), (pipH)[Cd(pyc)]·3HO ( 2) and [Mg(pyc)(HO)]·HO ( 3) (pycH: pyridine-2-carboxylic acid, pip: piperazine) were prepared using a proton transfer compound (pipH)(pyc) and corresponding metallic salts. The characterization was carried out using IR and NMR spectroscopies and single crystal X-ray diffraction. These complexes crystallize in the space group P2/ n of the monoclinic system. Cell parameters of the complexes are a = 9.769(2)Å, b = 5.157( 1)Å, c = 14.539(3)Å and β = 90.205(3)° for ( 1); a = 8.436(2)Å, b = 14.616(4)Å, c = 19.050(6)Å and β = 96.830(5)° for ( 2); a = 11.639(6)Å, b = 8.796(5)Å, c = 14.936(8)Å and β = 107.221(1)° for ( 3). The crystal structures of ( 1) and ( 3) complexes illustrate that the metal ions are coordinated by two pyridine-2-carboxylate but in crystal structure ( 2) the metal ion is coordinated by three pyridine-2-carboxylate. The protonation constants of the building blocks of the pyridine-2-carboxylic acid-piperazine adduct and the equilibrium constants for the reaction of pyridine-2-carboxylate with piperazine and the stoichiometry and stability of the Zn, Cd and Mg complexes with pycH in aqueous solution were accomplished by potentiometric pH titration. The corresponding stability constants, stoichiometry and distribution of the species were determined with program BEST. The solution studies strongly support the self-association and stoichiometry similar to that observed for the isolated crystalline complexes. [ABSTRACT FROM AUTHOR]

Abstract: In this work, we will report a combined experimental and theoretical study on molecular and vibrational structure of N,N′-di(p-thiazole)formamidine (DpTF). DpTF has been synthesized and characterized by elemental analysis, FT-IR, FT-Raman, 1H NMR, 13C NMR spectroscopy and X-ray single crystal diffraction. The FT-IR and FT-Raman spectra of DpTF were recorded in the solid phase. The optimized geometry was calculated by HF and B3LYP methods using 6-31G(d) basis set. The FT-IR and FT-Raman spectra of DpTF was calculated at the HF/B3LYP/6-31G(d) level and were interpreted in terms of potential energy distribution (PED) analysis. The scaled theoretical wavenumber showed very good agreement with the experimental values. A detailed interpretation of the infrared and Raman spectra of DpTF was reported. On the basis of vibrational analyses, the thermodynamic properties of the title compound at different temperatures have been calculated, revealing the correlations between C p,m °, S m °, H m ° and temperatures. Furthermore, molecular electrostatic potential maps (MESP) and total dipole moment properties of the compound have been calculated. [Copyright &y& Elsevier]

Two compounds containing a proton transfer ion pair (pipzH2)(btcH2), 1, and its Co(II) complex, were synthesized and characterized using IR spectroscopy and single crystal X-ray diffraction method. The chemical formula is {(pipzH2)[Co(btc)(H2O)4].4H2O}n for Co(II) complex, 2, (pipz:piperazine, btcH4:benzene-1,2,4,5-tetracarboxylic acid). The space group and crystal system of both compounds are P1 and triclinic. The proton transfer ion pair 1 was prepared by the reaction between piperazine and benzene-1,2,4,5-tetracarboxylic acid, and its Co(II) complex, 2, was synthesized by the reaction of 1 with cobalt(II) sulphate. The complex 2 is a polymeric substance with Co(II) atoms linked by two O atoms from one benzene-1,2,4,5- tetracarboxylate. In both crystal structures, a wide range of noncovalent interactions consisting of hydrogen bonding (types of OH ⋯O, N-H⋯O and C-H⋯O) and ion pairing interactions connecting the various components into a supramolecular structure. There are also C-H⋯O and C-H⋯χ intermolecular interactions in compound 2 which take part in the stabilization of molecular packing. The protonation constants of pipz and btcH4, the equilibrium constants for the btcH4-pipz proton transfer system and the stoichiometry and stability of this system with Co2+ ion in aqueous solution were investigated by potentiometric pH titrations. The stoicheiometry of one of the most abundant complexed species in solution was found to be the same as that of the crystalline cobalt(II) complex. [ABSTRACT FROM AUTHOR]