Sevi Öz

Experimental and computational investigations of a Cadmium(II) mononuclear complex with 2,6-Bis(3,5-dimethyl-N-pyrazolyl)pyridine (bdmpp) and selenocyanate as ligands

A new cadmium (II) complex, [Cd(bdmpp)(SeCN)2(H2O)] (1) (where bdmpp = 2,6-bis(3,5-dimethyl-N-pyrazolyl)pyridine), has been synthesized and characterized by elemental and spectral (IR, 1H-NMR and 13C-NMR, UV-Vis) analyses, differential scanning calorimetry, and single crystal X-ray diffraction studies. X-ray analysis showed that the structure was crystallized in the monoclinic space group Cc with a = 9.031(2), b = 13.884(3), c = 16.910(3) Å, and Z = 4. The geometry around the cadmium atom is distorted octahedral with a CdN3Se2O setup. The N atoms of the SeCN are engaged in two strong intermolecular H-bonding interactions forming a 3D supramolecular polymeric network. The geometry and vibrational frequencies of complex 1 computed with the DFT methods (BLYP, B3LYP, B3PW91, MPW1PW91) are in better agreement with experiment than those obtained with the ab-initio method except for the bond angles. The molecular orbital diagram has been also calculated and visualized at the B3LYP/LanL2DZ level of theory.

Heterodinuclear Ni(II)—Sn(II) complexes from reduced ONNO type Schiff base compounds

N,N´-bis(salicylidene)-1,3-propanediamine (LH2), N,N´-bis(salicylidene)-2,2´- dimethyl-1,3-propane-diamine (LDMH2), N,N´-bis(2-hydroxyacetophenylidene)-1,3-propanediamine (LACH2), N,N´-bis(2-hydroxyacetophenone)-2,2´-dimethyl-1,3-propanediamine (LACDMH2) and N,N´-bis(salicylidene)-1,2-ethylenediamine (SalenH2) were reduced in methanolic media with the help of NaBH4. Ni(II)—Sn(II) heteronuclear complexes were synthesized according to the template method in DMF media. The complex structures were analyzed using elemental analysis, FTIR spectroscopy, thermogravimetry and X-ray diffraction. Appropriate crystals for one of the complexes 2 were obtained for X-ray diffraction. The Ni(II) ion has an octahedral coordination between the organic donors. The Sn(II) ion forms three membered coordination structure with phenolic oxygen atoms via μ-bridges. The Ni … Sn bridging distance is 3.1543(9) Å.

Thermal Decomposition of Dinitro-chloro-azido Benzenes: A Comparison of Theoretical and Experimental Results

1,2-Dichloro benzene (I) and 1,2,3-trichloro benzene (II) were nitrated under appropriate strong conditions. Nitrated mixtures were reacted with NaN3 in polar solvents. As a result of the nucleophilic substitution, mixtures of nitro-chloro-azido benzene were prepared. After fractional crystallization, two crystalline substances were obtained from the mixtures. These crystalline substances were characterized by infrared (IR), 1H-NMR spectroscopy, mass spectroscopy, and elemental analysis. It was understood that the substance obtained from compound I was 2-chloro-4,6-dinitro azido benzene (III). The crystals of compound III were suitable for single-crystal X-ray diffraction (XRD). The molecular structure of this substance was determined by the mentioned method, XRD. It was revealed that the crystalline substance obtained from compound II was most probably 1,5-dinitro-2,4-diazido-3-chloro benzene (IV). In addition, compounds III and IV were investigated by thermogravimetry (TG) and differential scanning calorimetry (DSC). Compound III turned into 4-nitro-6-chloro phenoxazine (V) at about 120°C with an exothermic reaction. Compound IV completely decomposed at about 150°C with an exothermic reaction similar to that of explosive materials. In addition, theoretical formation enthalpies of compounds III and IV were calculated with Gaussian 09, CBS-4 M algorithm. The enthalpies of thermal reactions observed in the TG curves were calculated using the theoretical formation enthalpies. Finally, the theoretical results were compared with the experimental findings obtained from DSC.

Synthesis, crystal structure, chromatographic seperation, and thermogravimetric investigation of a ONNO type asymmetric Schiff base and its trinuclear complexes

Abstract1,3-Propanediamine was put to react with 2-hydroxybenzaldehyde and 2-hydroxyacetophenone sequentially in aprotic medium. The crystalline product was examined by high performance liquid chromatography. The composition was 66% asymmetric Schiff base N(2-hydroxybenzylidene)-N′(2-hydroxyacetophenone)-1,3-propanediamine (SALLACH2) and 33% bis-N,N′(2-hydroxyacetophenylidene)-1,3-propanediamine (LACH2). As the crystals were uniform and of appropriate size, the molecular model of the material was revealed by X-ray diffraction. It was seen that two molecules of SALLACH2 and one molecule of LACH2 formed the mixed crystals. The substance was separated to its components and the asymmetric Schiff base was purified with a silica column. The substance was characterized with elemental analysis, FT-IR, MS, 1HNMR, and 13C NMR. In addition, six tri-nuclear complex with the nuclear structure of NiII-NiII-NiII, NiII-CuII-NiII, NiII-MnII-NiII were prepared from this Schiff base and stoichiometry was determined by elemental analysis, FT-IR and thermogravimetry. Finally, the molecular structures of two complexes were brought to light by XRD which highlights the asymmetry of the ligand more clearly.

Thermal kinetic analysis, theoretical thermodynamic calculations and antimicrobial activity of three new energetic materials

Three new energetic agents were synthesized using 3,5-dinitro-4-chlorobenzonitrile, sodium azide and hydrazine, which were 2,6-dinitro-4-cyano-azidobenzene (I), N-2,6-dinitro-cyanophenyl-hydrazine (II) and bis-N,N′(2,6-dinitro-4-cyanophenyl)hydrazine (III). These energetic substances were first characterized by elemental analysis, IR, mass, 1H NMR and 13C NMR spectroscopic methods. The energetic substances were studied by thermogravimetry, and it was understood that the mechanism of the thermal decomposition reactions consists of two successive exothermic thermal reactions. In the first thermal reaction, the energetic material was converted to furoxane compounds, and then, these furoxane compounds were decomposed by the second thermal reaction. Activation energies and Arrhenius pre-exponential factors of thermal responses were determined by using isothermal (Coats–Redfern) and nonisothermal/isoconvertional (Kissinger–Akahira–Sunose, Ozawa–Flynn–Wall) methods with thermogravimetry and differential scanning calorimetry (DSC) data. With these calculated values, other thermodynamic parameters reaction enthalpy, entropy changes and free energy were calculated. Formation enthalpies of the elements of the energetic substances were theoretically calculated using the CBS-4M algorithm in the Gaussian 09 program for the synthesized energetic substances. In the thermal decomposition reactions, the products were estimated with the aid of literature data and the enthalpies of explosion reactions were theoretically calculated according to the Hess Law. Besides, the exothermic energies in the first and second thermal reactions of the energetic substances were measured by DSC. The results measured by DSC were compared with the calculated theoretical results and were found to be very close to each other. In the study, antimicrobial activity was estimated to be high because energetic molecules are strained molecules, and it is possible this tension can affect the medium. According to this thought, antimicrobial activity was determined by using five different bacteria and a fungus. Antimicrobial activity values were determined by “agar dilution” method, and results were found as minimum inhibition concentration. Among the three energetic substances, 2,6-dinitro-4-cyano-azidobenzene was found to have the most active compound.

Synthesis, crystal structure, and thermal decomposition of two Co(II) complexes with NNN pyrazolyl type ligand and pseudo-halogen

The Co(II) complexes I and II were prepared in nonaqueous solvents containing cyanate with pyrazolylpyridine ligands, namely, bis-2,6-(pyrazol-1-yl) pyridine (Pp) and bis-2,6-(3,5-dimethyl-pyrazol-1-yl) pyridine (Dmpp), respectively. These complexes were characterized with elemental analysis, IR spectroscopy, and X-ray diffraction techniques. X-ray diffraction study revealed that complex I was mononuclear and complex II was dinuclear and ionic. The ionic complex II has an octahedral cationic coordination sphere and a tetrahedral anionic coordination sphere. Thermogravimetry results showed that the thermal decomposition is starting with the carbon content of the pyrazolyl rings.

Synthesis, crystal structure, thermal decomposition, and XPS studies of homo and heterotrinuclear Cu(II)–Cu(II)–Cu(II) and Cu(II)–Ni(II)–Cu(II) complexes obtained from salpn type ligands

In this study, a mononuclear CuL complex was prepared by the use of bis-N,N′-(salicylidene)-1, 3-propanediamine (LH2) and Cu2+ ion. NiCl2 and NiBr2 salt were treated with this complex in dioxanewater medium and two new complexes [(CuL)2NiCl2(H2O)2] and [(CuL)2NiBr2(H2O)2)] with Cu(II)–Ni(II)–Cu(II) nucleus structure were obtained. In addition to this bis-N,N′-(2-hydroxybenzyl)-1,3-diaminopropane (LHH2) was prepared by the reduction of LH2 with NaBH4 in MeOH medium. The treatment of this reduced complex with Cu2+ ion resulted a complex [(CuLH)2CuCl2] with a structure of Cu(II)–Cu(II)–Cu(II). The complexes prepared were characterized by the use of elemental analysis, IR spectroscopy, thermogravimetric and X-ray diffraction methods. The crystal structures of [(CuL)2NiBr2(H2O)2] (СIF file CCDC 1448402) and [(CuLH)2CuCl2] (СIF file CCDC 1448401) complexes were elucidated. It was found that halogen ions are coordinated to terminal Cu2+ ions which are in a distorted square pyramid coordination sphere. It was determined that the central Cu(II), which joins terminal square pyramidal Cu(II), was coordinated only by the phenolic oxygens of the ligand while the central Ni(II) was coordinated by two phenolic oxygens of the organic ligand and two water molecules. These complexes were investigated by XPS and it was found that the terminal and central Cu2+ ions were different in Cu(II)–Cu(II)–Cu(II) complex. Also, the thermal degradation of the CuLH complex unit was observed to exothermic in contrast to the expectations.