bis(nicotinamide) and bis(N,N-diethyl nicotinamide) p-hydroxybenzoate complexes of Ni(II), Cu(II) AND Zn(II)

The mixed-ligand p-hydroxybenzoate complexes of Ni(II), Cu(II) and Zn(II) with nicotinamide and N,N-diethylnicotinamide were synthesized and characterized by elemental analysis, magnetic susceptibility measurements and mass spectrometry. The thermal behavior of the complexes was studied by simultaneous TG, DTG and DTA methods in static air atmosphere. The infrared spectral characteristics of the complexes are also discussed. The complexes contain two water molecules, two p-hydroxybenzoato (p-hba) and two nicotinamide (na) (or diethylnicotinamide (dena)) ligands per formula unit. In these complexes, all ligands are coordinated to the metal ion as monodendate ligands. In Zn(II)-na and Cu(II)-dena complexes, thep-hydroxybenzoate behaves as bidentate chelating ligand through carboxylic oxygen atoms. The decomposition pathways and the stability of the complexes are interpreted in the terms of the structural data. The final decomposition products were found to be the respective metal oxides. This revised version was published online in July 2006 with corrections to the Cover Date.     

Diaquabis(5-methoxyindole-2-carboxylato)bis(3-picoline)nickel(II) Complex: Synthesis,Characterization, XRD,TGA, DFT and HSA

A new complex of diaquabis(5-methoxyindole-2-carboxylato)bis(3-picoline)nickel(II) (Ni(5-MeOI2CA)₂(3-pic)₂(H₂O)₂), was synthesized for the first time and characterized by elemental analysis, FT-IR and electronic spectroscopy (UV-Vis) and single-crystal X-ray diffraction (XRD) techniques. The thermal degradation of the Ni(II) complex was investigated using thermogravimetric and differential thermal analyses techniques in oxygen atmosphere. The molecular structure of the complex was determined by single crystal X-ray diffraction technique. Hirshfeld surface analysis (HSA) investigated the packing modes and intermolecular interactions in molecular crystals, as they provide a visual picture of intermolecular interactions. In addition, all computational studies at B3LYP/6-311++G(d,p) were carried out for theoretical characterization of Ni(II) complex. The optimized geometry results, which were well represented the X-ray data, were shown that the chosen of DFT/B3LYP/6-311++G(d,p) was a successful choice for title compound. After a successful optimization, FMOs, chemical activity, non-linear optical properties (NLO), molecular electrostatic potential (MEP), Mulliken population (MPA), natural population analyses (NPA), Fukui function analysis (FFA) and natural bond orbital analysis (NBO), which could not obtained by experimental ways, were calculated and investigated. The computed of net charges and chemical activity studies which helped to identifying the electrophilic/nucleophilic nature.     

One‐pot New Barbituric Acid Derivatives Derived from the Reaction of Barbituric Acids with BrCN and Ketones

Reaction of cyclic β‐dicarbonyl compounds such as pyrimidine‐(1H,3H,5H)‐2,4,6‐trione (BA), 1,3‐dimethyl pyrimidine‐(1H,3H,5H)‐2,4,6‐trione (DMBA) and 2‐thioxo‐pyrimidine‐(1H,3H,5H)‐4,6‐dione (TBA) with cyanogen bromide in acetone and 2‐butanone in the presence of triethylamine afforded a new class of stable heterocyclic spiro[furo[2,3‐d]pyrimidine‐6,5′‐pyrimidine]2,2′,4,4′,6′(3H,3′H,5H)‐pentaones (dimeric forms of barbiturate) at 0 °C and ambient temperature. Structure elucidation was carried out by X‐ray crystallographic, ¹H NMR, ¹³C NMR, two dimensional NMR, FT‐IR spectra, mass spectrometry and elemental analysis. The mechanism of product formation is discussed. The reaction of DMBA with cyanogen bromide in the presence of triethylamine also afforded trimeric form of barbiturate of uracil derivatives in good yield. The reaction of selected acyclic β‐dicarbonyl compounds with cyanogen bromide in the presence of triethylamine in acetone and/or diethyl ether has also been investigated under the same condition. Diethyl malonate and ethyl cyanoacetate brominated and also ethyl acetocetate both brominated and cyanated on active methylene via cyanogen bromide.     

Decomposition pathway of diaquabis(N,N'-dimethyl-1,2-ethanediamine)Ni(II) acesulfamate

Summary Prediction of the thermal decomposition pathway of the metal complexes is very important from the theoretical and experimental point of view to determine the properties and structural differences of complexes. In the prediction of the decomposition pathways of complexes, besides the thermal analysis techniques, some ancillary techniques e.g. mass spectroscopy is also used in recent years. In the light of the molecular structures and fragmentation components, it is believed that the thermal decomposition pathway of most molecules is similar to the ionisation mechanism occurring in the mass spectrometer ionisation process. In this study, the thermal decomposition pathway of [Ni(dmen)₂(H₂O)₂](acs)₂ complex have been predicted by the help of thermal analysis data (TG, DTG and DTA) and mass spectroscopic fragmentation pattern. The complex was decomposed in four stages: a) dehydration between 84-132°C, b) loss of N,N'-dimethylethylenediamine (dmen) ligand, c) decomposition of remained dmen and acesulfamato (acs) by releasing SO₂, d) burning of the organic residue to resulting in NiO. The volatile products observed in the thermal decomposition process were also observed in the mass spectrometer ionisation process except molecular peak and it was concluded that the ionisation and thermal decomposition pathway of the complex resembles each other.     

Synthesis,Spectrothermal and Structural Characterization of Saccharinatobis(tris‐hydroxymethylaminomethane)zinc(II)saccharinate Complex, [Zn(sac)(tham)2](sac)

A novel Zn^II complex of the saccharinate ligand (sac) with tris‐hydroxymethylaminomethane (tham) was synthesized and characterized by elemental analysis, FT‐IR spectroscopy, simultaneous TG and DTA techniques, and X‐ray diffraction. The complex, [Zn(sac)(tham)₂](sac), crystallizes in monoclinic system with space group P2₁/c [a = 7.55954(3) Å, b = 13.0532(6) Å, c = 27.7777(10) Å, β = 100.539(3)°, Z = 4]. The Zn^II ion has a distorted octahedral coordination. The tham ligand has chemically different functions in the structure, acting as both bidentate and tridentate ligands. There are also sac moieties to act as N‐bonded ligand and as a counter anion. The molecular packing of the complex is provided by moderate hydrogen bonds as well as π···π interactions between the sac moieties. The IR spectra and the thermal decomposition of the complex are also discussed.