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Vol 43, No 5 (2017)
- Year: 2017
- Articles: 9
- URL: https://journals.rcsi.science/1070-3284/issue/view/13317
Article
Syntheses and structural studies of the nickel(II) octahedral complexes Ni(N∩N)xL2 with nitrogen-containing and carboxylate ligands
Abstract
A series of new mononuclear octahedral nickel(II) complexes with the Ni(N∩N)xL2 framework (x = 2 or 3, N∩N = Рhen (1,10-phenanthroline), AMPy (2-(aminomethyl)pyridine), L is H2O, anions of carboxylic acids (CF3CO2−, CCl3CO2−, HCO2−), chloride ion, and water) is synthesized and described by IR spectroscopy, mass spectrometry, elemental analysis, and X-ray diffraction analysis: [Ni(Рhen)2(OH2)Cl]Cl · 2H2O (I), [Ni(Рhen)2(OH2)(O2CCF3)](O2CCF3) (II, IIa), [Ni(Рhen)2(HCOO)1.618(H2O)0.382](HCOO)0.382 · 4.618H2O (III), ([Ni(Рhen)2(OH2)2](O2CCCl3)2 · 6.2H2O (IV), [Ni(AMPy)2(OH2)2](HCO2)2 · 6H2O (V), and [Ni(Рhen)3](CCl3COO)2 · 7H2O (VI). The subunit containing two formate ligands in the inner sphere of the [Ni(Рhen)2(HCO2)2] complex prevails in the crystal structure of complex III, which is not characteristic of the nickel carboxylate complexes of this type. In aqueous solutions complex IV undergoes decarboxylation to form [Ni(Рhen)2(CO3)] · 7H2O. A change in the nature of the N-donor ligands in Ni(N∩N)2L2 leads to the change (cis or trans) in the configuration of the whole complex (СIF files CCDC no. 880414 (I), 842336 (II), 1430414 (IIa), 1478111 (III), 1430430 (IV), 1443133 (V), and 1430415 (VI)).
269-277
Synthesis and structure of mononuclear zinc complexes with pyridine-2-aldoxime
Abstract
Three mononuclear different-ligand Zn(II) complexes, [Zn(CH3COO)2(PaoH)2] (I), [Zn(PaoH)2(DMSO)2][BF4]2 (II), and [Zn(NCS)2(PaoH)2] (III) (DMSO = dimethylsulfoxide) were prepared by the reaction of zinc acetate and tetrafluoroborate with pyridine-2-aldoxime (PaoH). The composition and structure of the complexes were confirmed by IR spectroscopy and X-ray diffraction. All compounds crystallize in the monoclinic system, compounds I and II have space group P21/n, while compound III has space group C2/c. In all compounds, the Zn coordination polyhedron is a distorted octahedron, which is formed by the N4O2 sets of donor atoms in I and II and by N6 in III. Complex I in the optimal concentration of 5–10 mg/L was found to stimulate the biosynthesis of standard (pH 4.7) amylases by the micromycete Aspergillus niger CNMN FD 06.
278-285
Principles of supramolecular polymeric chain formation in heteronuclear gold(III)–iron(III) complexes ([Au(S2CNR2)2][FeCl4])n (R = C3H7, iso-C3H7): Chemisorption synthesis, structural organization, and thermal behavior
Abstract
Polymeric gold(III)–iron(III) dithiocarbamate–chloride complexes of the ionic type are synthesized by the chemisorption binding of gold(III) with freshly precipitated iron(III) dipropyl and di-iso-propyl dithiocarbamates from solutions of H[AuCl4] in 2 M HCl. Heteropolynuclear complexes of the compositions ([Au{S2CN(C3H7)2}2][FeCl4])n (I) and ([Au{S2CN(iso-C3H7)2}2][FeCl4])n (II) are preparatively isolated as individual forms of gold(III) binding. The structural organization of the complexes is established by X-ray diffraction analysis (CIF files CCDC no. 1480802 (I) and no. 1480806 (II)). The structures of compounds I and II are characterized at the supramolecular level by the presence of two types of polymeric chains, the methods of formation of which differ substantially. Compound I contains the following structural units: four structurally nonequivalent centrosymmetric complex cations [Au{S2CN(C3H7)2}2]+ (A, B, С, and D) and two complex anions [FeCl4]– related to each other as conformers. Two independent cation-cationic linear polymeric chains (···А···В···)n and (···С···D···)n are formed in the structure of complex I due to pair relatively weak secondary interactions Au···S (nonvalent type) between the adjacent complex cations. The structure of compound II is characterized by zigzag cation-anionic chains (···[Au{S2CN(iso-C3H7)2}2]+···[FeCl4]–···)n in the formation of which the secondary interactions Au···Cl play the determining role. The thermal behavior of complexes I and II is studied by simultaneous thermal analysis. The thermal destruction process includes the thermolysis of the dithiocarbamate moiety of the complexes and [FeCl4]− with the reduction of gold(III) to the metal, the liberation of FeCl3, and the partial transformation of the latter into Fe2O3. In both cases, the final products of the thermal transformations of the studied compounds are elemental gold and Fe2O3.
286-296
Structures and optical and electrochemical properties of the Pt(II) and Pd(II) complexes with cyclometallated 2-phenylbenzothiazole and 1,4,7-trithiocyclononane
Abstract
The distorted square pyramidal structures of the Pt(II) and Pd(II) complexes with cyclometallated 2-phenylbenzothiazole and flexible 1,4,7-trithiocyclononane are shown by X-ray diffraction analysis, IR spectroscopy, and 1Н, 13С{1H{, and 195Pt NMR spectroscopy. The axial interaction of the dZ2 orbital of Pt(II) and Pd(II) with the S atom of 1,4,7-trithiocyclononane results in the temperature quenching of the intraligand phosphorescence of the cyclometallated complexes in a solution and the one-electron ligand- and metal-centered reduction and oxidation of the complexes with the formation of the relatively stable Pd(III) complex (CIF file CCDC no. 1483011).
297-303
Synthesis and structural determination of 2D ladder-like mononuclear nine-coordinate (EnH2)[NdIII(Egta)H2O]2 · 6H2O and ten-coordinate (EnH2)1.5[NdIII(Ttha)] · 5H2O
Abstract
Two novel lanthanide complexes, (EnH2)[NdIII(Egta)H2O]2 · 6H2O (I) and (EnH2)1.5[NdIII(Ttha)] · 5H2O (II), where En = ethylenediamine, H4Egta = ethyleneglycol-bis-(2-aminoethylether)-N,N,N′,N'-tetraacetic acid and H6Ttha = triethylenetetramine-N,N,N',N'',N''',N'''-hexaacetic acid, have been successfully synthesized through direct heating reflux and their molecular and crystal structures were determined by FT-IR spectroscopy, thermal analysis and single crystal X-ray diffraction (CIF files CCDC nos. 1436598 (I) and 1433221 (II)). X-ray diffraction reveals that I has a nine-coordinate mononuclear structure with pseudo-monocapped square antiprismatic conformation. Complex I crystallizes in a monoclinic system with P21/c space group; a = 13.0919(12), b = 12.6840(11), c = 16.9751(14) Å, β = 122.069(3)° and V = 2388.7(4) Å3. Complex II takes ten-coordinated structure with a distorted bicapped square antiprismaticprism belong to triclinic crystal system with P1 space group; a = 9.9376(10), b = 12.2178(12), c = 15.2671(16), β = 100.2480(10)° and V = 1609.5(3) Å3. Each EnH22+ cation in I connects four adjacent [NdIII(Egta)H2O]– anions through hydrogen bonds. In II crystal cell, there are two types of cations, which form hydrogen bonds with the neighboring [NdIII(Ttha)]3– anions, leading to the formation of a 2D ladder-like layer structure. The results showed that the change of ligands can lead to change of the structure of the complexes, coordination numbers and coordination geometries. Thus, it can be concluded that the shape of ligands play a crucial role on the coordinate structure of complexes, coordination numbers and coordination geometries.
304-313
Synthesis, X-ray crystal structures, and antibacterial activities of Schiff base nickel(II) complexes with similar tetradentate Schiff bases
Abstract
Two new mononuclear complexes, [NiL1] · CH3OH (I) and [NiL2] (II), have been prepared from the tetradentate Schiff bases N,N'-bis(5-methylsalicylidene)ethylenediamine (H2L1) and N,N'-bis(5-methylsalicylidene)- o-phenylenediamine (H2L2), respectively. The complexes have been characterized by physico-chemical and spectroscopic methods, as well as single-crystal X-ray determination (CIF files nos. 1428969 (I), 1428968 (II)). Complex I crystallizes in the triclinic space group P1 with a = 6.7387(14), b = 10.7010(17), c = 12.681(2) Å, α = 87.059(2)°, β = 88.828(2)°, γ = 89.901(2)°, V = 913.0(3) Å3, Z = 2. Complex II crystallizes in the monoclinic space group P21/n with a = 12.1437(11), b = 8.0537(8), c = 18.4545(18) Å, β = 105.088(2)°, V = 1742.7(3) Å3, Z = 4. The nickel atoms in the complexes are coordinated by two phenolate O and two imine N atoms of the tetradentate Schiff base ligands, forming square planar coordination. The complexes and the Schiff base compounds were assayed for antibacterial activities against three Gram-positive bacterial strains (B. subtilis, S. aureus, and St. faecalis) and three Gram-negative bacterial strains (E. coli, P. aeruginosa, and E. cloacae) by MTT method. As a result, the complexes showed effective antimicrobial activity against the microorganisms tested.
314-319
Synthesis, characterization, and biological activity of Cd(II) and Mn(II) coordination polymers based on pyridine-2,6-dicarboxylic acid
Abstract
The coordination polymers (CPs) {[Cd(Pydc)(H2O)3] · PydcH2} (I) and [Mn(Pydc)(H2O)3] · PydcH2} (II) were obtained by the reaction of CdSO4 · 5H2O or MnCl2 · 4H2O with pyridine-2,6-dicarboxylic acid (PydcH2). The structures of the CPs I and II were characterized by IR, UV-Vis, TGA, and X-ray single crystal analysis (CIF files CCDC nos. 1417757 (I), 1417758 (II)). The network structures of I and II are constructed by an infinite number of discrete binuclear molecules and free PydcH2. The structures of the CPs I and II connected by the extensive H-bonds and π–π stacking, forming a 3D-network. The CPs I and II were screened to test their antimicrobial activities against different species of bacteria and fungi.
320-330
Synthesis and crystal structures of N,N'-bis(5-methylsalicylidene)ethane-1,2-diamine and its bromido-, phenolato-, and dicyanoamido-cobridged polymeric copper(II) complex
Abstract
A bis-Schiff base N,N'-bis(5-methylsalicylidene)ethane-1,2-diamine (H2L) was prepared and characterized by elemental analysis, 1H NMR and 13C NMR spectra, MS, and single crystal X-ray diffraction (CIF file CCDC no. 1022761 (H2L)). Reaction of the Schiff base with copper bromide and sodium dicyanoamide in methanol gave a novel bromido-, phenolato-, and dicyanoamido-cobridged polymeric copper(II) complex, ({Cu2LBr[N(CN)2]}2)n (I). Structure of complex I was characterized by elemental analysis and single crystal X-ray diffraction (CIF file CCDC no. 1022762 (I)). The smallest repeat unit of complex I is a dicyanoamide bridged tetranuclear copper(II) complex moiety, {Cu2LBr[N(CN)2]}2, in which there possesses a crystallographic inversion symmetry. The tetranuclear moieties are further linked through Br atoms, forming a zigzag chain. The chains are further linked by dicyanoamide ligands, forming a 2D network. One Cu atom in complex I is coordinated by two N and two O atoms of the Schiff base ligand and one Br atom, forming square pyramidal geometry. The other Cu atom is coordinated by two N atoms of the Schiff base ligand, two N atoms of dicyanoamide ligands, and one Br atom, forming square pyramidal geometry. The bromido-, phenolato-, and dicyanoamido-cobridged Cu···Cu distances are 4.823(2), 2.955(1), and 7.121(3) Å, respectively. The [Cu2L] units are linked by the bridging groups, to form 2D chains along the xy plane.
331-337
Two novel coordination polymers: Synthesis, structure, luminescent properties, and selective sensing of Cu2+ and Mn2+ ions
Abstract
Two novel coordination polymers, namely {[Co(Ttac)0.5(1,4-Bib)(H2O)] · H2O}n (I) and {[La(HTtac)2(2H2O)] · H2O}n (II) (H4Ttac = 4,5-di(3'-carboxylphenyl)-phthalic acid, 1,4-Bib = 1,4-bis(1-imidazoly) benzene), have been designed and successfully prepared via hydrothermal process, and characterized by elemental analyses, IR spectroscopy, and single crystal X-ray diffraction (CIF files CCDC nos. 1039298 (I), 1039300 (II)). Structural analysis reveals that the H4Ttac ligands adopt different coordination modes in the as-synthesized I and II, and thus give rise to the targeted coordination polymers with different configurations. It is worth mentioning that, coordination polymer I is assembled from low-dimensional structures into three-dimensional (3D) via π···π stacking interactions, while three-dimensional coordination polymer II is formed by covalent bonds. Luminescent properties of coordination polymer II have been studied at ambient temperature. Significantly, luminescent measurement indicates that coordination polymer II may be acted as potential luminescent recognition sensors towards Cu2+ and Mn2+ ions.
338-344