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Search Results: 1 - 10 of 2664 matches for " Justin Nenwa "
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Synthesis, Crystal Structure and Thermal Behavior of a 3-D Barium(II)/Iron(III)-Oxalate Polymer  [PDF]
Noé Makon Ma Houga, Brian S. Dolinar, Justin Nenwa, Gouet Bebga
Open Journal of Inorganic Chemistry (OJIC) , 2014, DOI: 10.4236/ojic.2014.42004
Abstract: Reaction of Ba(NO3)2 with Fe(NO3)9H2O and H2C2O2H2O in aqueous medium readily affords, in high yield, the bimetallic complex polymer of chemical composition {Ba6(H2O)17[Fe(C2O4)3]4}·7H2O (1), consistent with the expected ratio of 3BaII vs. 2FeIII. Compound 1 was fully characterized by elemental and thermal analyses, vibrational FTIR spectroscopy, and by single crystal X-ray structure determination. The bulk structure of 1 is a 3-D metal-organic framework held together by intermetallic linkages across oxalate and aqua oxygen bridgings.
A Chiral Three Dimensional Potassium(I)/Strontium(II)/Chromium(III) Oxalato-Bridged Coordination Polymer: Synthesis, Characterization and Thermal Analysis  [PDF]
Justin Nenwa, Issoufou Kaboré, Yves A. Mbiangué, Patrick L. Djonwouo, Peter T. Ndifon
Crystal Structure Theory and Applications (CSTA) , 2014, DOI: 10.4236/csta.2014.34008
Abstract: A new compound of general formula {[(H2O)2K(μ-H2O)Sr]@[Cr(C2O4)3]}n (1) has been synthesized in water and characterized by elemental and thermal analyses, EDX, IR and UV-Vis spectroscopies and by single crystal X-ray structure determination. Compound 1 crystallizes in the chiral space group Fdd2 of orthorhombic system with a = 14.110 (4) ?, b = 36.074 (11)?, c =11.034 (3)? and Z = 16. Compound 1 is a coordination polymer in which the three-dimensional lattice framework is realized by the interconnectivity between K+ cations, Sr2+ cations, aqua ligands and [Cr(C2O4)3]3 complex anions. The asymmetric unit of 1 consists of one cationic motif formally written [(H2O)2K(μ-H2O)Sr]3+ and one anionic entity, [Cr(C2O4)3]3. The K+ and Sr2+ ions in the cationic motif are both eight-coordinate while the Cr3+ ions in the anionic complex are six-coordinate in a distorted octahedral geometry. Coulombic interactions between the ionic motifs and the three-dimensional H-bonding involving aqua ligands help to consolidate the bulk structure. Thermogra-vimetric analysis (TGA) shows that compound 1 is stable to heat up to ca. 80.
Synthesis and Crystal Structure of the First Example of a Tris-Chelated Co(II) Complex Based on Oxamide Dioxime Ligand  [PDF]
Gouet Bebga, Emmanuel N. Nfor, Yves A. Mbiangué, Patrick L. Djonwouo, Justin Nenwa
Crystal Structure Theory and Applications (CSTA) , 2015, DOI: 10.4236/csta.2015.42002
Abstract: A new cobalt(II) complex, [Co(H2 oxado)3 ]C2 O4 H2 oxado·2H2 O (H2 oxado = oxamide dioxime), has been synthesized in aqueous solution and characterized by elemental analysis and single crystal X-ray structure determination. The complex crystallizes in the triclinic space group P-1, with the parameters a = 9.46(4), b = 11.84(5), c = 12. 81(5)?Å, α = 104.94(6), β = 99.29(5), γ = 106.73(5), V = 1284(9) Å3, Z = 2. The central cobalt(II) cation is pseudo-octahedrally coordinated by six imino N atoms of the neutral oxamide dioxime ligand. In the solid state, each of the following bricks, namely the cationic complexes, the oxalate dianions as well as the oxamide dioxime crystallization molecules, pile up parallel to the a axis. The bulk structure is consolidated by an extended three-dimensional network of hydrogen bridgings—that link the ionic partners, oxamide dioxime and water molecules to one another—and by coulombic interactions.
Synthesis, Characterization and X-Ray Structure of a Ba(II)/Ag(I)/Cr(III)-Oxalate Salt with Water-Filled Nanochannels  [PDF]
Clémence Eboga Tanke, Bridget N. Ndosiri, Yves A. Mbiangué, Gouet Bebga, Justin Nenwa
American Journal of Analytical Chemistry (AJAC) , 2016, DOI: 10.4236/ajac.2016.71010
Abstract: A novel mixed barium(II)/silver(I)/chromium(III) oxalate salt, Ba0.5Ag2[Cr(C2O4)3]·5H2O (1), with open architecture has been synthesized in water and characterized by elemental analysis, vibrational and electronic spectra, and single crystal X-ray structure determination. Compound 1 crystallizes in a monoclinic space group C2/c, with unit cell parameters a = 18.179(3), b = 14.743(2), c = 12.278(2)Å, β = 113.821(3), V = 3010.34(90) Å3, Z = 8. The structure is characterized by a network of anionic [Cr(C2O4)3]3- units connected through the O atoms of the oxalates to Ba2+ and Ag+ sites, forming a three-dimensional coordination polymer with one-dimensional isolated nanochannels parallel to the c axis, and encapsulating hydrogen-bonded guest water molecules. The bulk structure is consolidated by O–H···O bridgings within the nanochannels and by coulombic interactions.
Synthesis, Structural Characterization and DFT Studies of Silver(I) Complex Salt of Bis(4,5-dihydro-1H-benzo[g]indazole)  [PDF]
Tanyi Rogers Fomuta, Golngar Djimassingar, Jean Ngoune, Nana Odette Ngnabeuye, Jean Jacques Anguile, Justin Nenwa
Crystal Structure Theory and Applications (CSTA) , 2017, DOI: 10.4236/csta.2017.62002
Abstract: A new silver complex salt [Ag(N2C11H10)2]NO3 (where N2C11H10 = 4,5-dihydro-1H-benzo[g]indazole), has been synthesized and characterized by elemental and thermal analyses, IR and 1HNMR spectroscopies, single crystal X-ray structure determination and DFT studies. Its molecular structure comprises of a silver center coordinated to two nitrogen atoms from two 4,5-dihydro-1H-benzo[g]indazole molecule giving rise to a cationic complex entity, [Ag(N2C11H10)2]+ with \"\" as counter ion. The bulk structure is consolidated by N–HO, C–Hπ, Agπ and AgO intermolecular interactions, thus generating a pseudo-helical network. The optimized structure, frontier molecular orbitals (HOMO and LUMO) and global reactivity descriptors were investigated by performing DFT calculations.
Synthesis, Rietveld Refinement and DFT Studies of Bis(4,5-dihydro-1H-benzo[g]indazole)silver(I) Hexafluorophosphate Complex Salt  [PDF]
Tanyi Rogers Fomuta, Jean Ngoune, Golngar Djimassingar, Tayo Alain Djampouo, Junior Ma Ntep Tobie Matemb, Jean Jacques Anguile, Justin Nenwa
Open Journal of Inorganic Chemistry (OJIC) , 2017, DOI: 10.4236/ojic.2017.74007
Abstract: The new salt bis(4,5-dihydro-1H-benzo[g]indazole)silver(I) hexafluorophosphate, [Ag(N2H10C11)2]PF6, has been synthesized in methanol at ambient temperature and characterized by elemental and thermal analyses, FTIR and 1HNMR spectroscopies, Rietveld refinement from powder diffraction data and DFT studies. The salt crystallizes in the triclinic space group P-1 with the parameters: a = 7.776 , b = 8.676 ?, c = 9.226 ?, α = 69.27° β = 89.86°, γ = 74.50°, V = 558.02 ?3, Z = 1. In the structure, the silver center is coordinated to two nitrogen atoms from two 4,5-dihydro-1H-benzo[g]indazole ligands, forming a centrosymmetric complex cation, [Ag(N2H10C11)2]+, with a linear coordination geometry around the silver center. The hexafluorophosphate ion, \"\" , acts as counter anion. The crystal packing is governed by N-H···F and C-H···F hydrogen bonds that interconnect the ionic constituents and Ag···F and Ag···π interactions help for the stabilization of the packing. The optimized structure was obtained at B3LYP/LanL2DZ level in the gas phase. The stability and reactivity of the structure were studied using respectively HOMO-LUMO gap and electronic global quantities (ionization potential (I) and electron affinity (A)) as descriptors.
A Novel Mixed Ligand Dinuclear Complex of Cobalt (II): Synthesis, Characterization and Magnetic Studies  [PDF]
Emmanuel N. Nfor, Luke L. Keenan, Justin Nenwa, Peter T. Ndifon, Romanus N. Njong, Christelle N. T. Dzesse, Offiong E. Offiong
Crystal Structure Theory and Applications (CSTA) , 2014, DOI: 10.4236/csta.2014.31003
Abstract:

A novel dinuclear complex [Co2(atr)3(mal)2(H2O)2]·4H2O(1) (atr = 4-amino-1,2,4-triazole and mal = malonic acid) containing mixed N and O-donor atoms has been prepared and structurally characterized. The structure is made up of the symmetrically 1, 2, 4-triazole bridged [Co2(atr)3(mal)2(H2O)2] moiety and four lattice water molecules. The single crystal X-ray analysis reveals that the complex has a distorted octahedral structure. Magnetic susceptibility measurements reveals that antiferromagnetic interactions exists between the high spin Co(II) ions within the dinuclear unit.

Anionic Nanochanneled Silver-Deficient Oxalatochromate(III) Complex with Hydroxonium as Counter Ion: Synthesis, Characterization and Crystal Structure  [PDF]
Clémence T. Eboga, Gouet Bebga, Yves A. Mbiangué, Emmanuel N. Nfor, Patrick L. Djonwouo, Michel M. Bélombé, Justin Nenwa
Open Journal of Inorganic Chemistry (OJIC) , 2017, DOI: 10.4236/ojic.2017.73005
Abstract: Reaction of Ba0.50[Ag2Cr(C2O4)3]·5H2O with Ag2SO4 in an aqueous solution of sulfuric acid (pH ≈ 3) yielded the silver(I)/chromium(III) oxalate salt H0.50[Ag2.50Cr(C2O4)3]·5H2O (1). Compound 1 can be best described as an anionic silver-deficient oxalatochromate(III) complex [Ag2.50Cr(C2O4)3]0.5- with nanochannels containing hydrogen-bonded water molecules and protons. Thermal analyses show significant weight losses corresponding to the elimination of water molecules of crystallization followed by the decomposition of the network.
{[Na1(μ-H2O)Na2]2[(C2O4)2Cr(μ-OH)2Cr(C2O4)2]·H2O}n, a novel hydrated form
Michel M. Bélombé,Justin Nenwa,Jean Ngouné,Eleuterio Álvarez
Acta Crystallographica Section E , 2010, DOI: 10.1107/s1600536810023986
Abstract: The unit cell of the title compound, poly[[μ-aqua-μ-hydroxido-di-μ-oxalato-chromium(III)disodium] monohydrate], {[CrNa2(C2O4)2(OH)(H2O)]·H2O}n, contains four [Na1(μ-H2O)Na2][(C2O4)2Cr(μ-OH)·H2O] formula units, each of which consists of two crystallographically independent Na+ sites (bridged by one aqua ligand), one half of a centrosymmetric di-μ-hydroxido-bis[cis-bis(oxalato)chromate(III)] dimer, [(C2O4)2Cr(μ-OH)2Cr(C2O4)2]4 , and one uncoordinated water molecule. The structure is best described as a coordination polymer in which the three-dimensional lattice framework is realized by the interconnection of the metallic atoms via the O atoms of the aqua, hydroxide and oxalate ligands. One Na atom is heptacoordinated by one water, one hydroxide and five oxalate O atoms, whilst the other is pentacoordinated by one water and four oxalate O atoms. The coordination around the Cr3+ sites is pseudo-octahedral, involving four aqua and two hydroxide O atoms. Adjacent Na atoms are separated by 3.593 (2) , whereas the intradimer Cr...Cr spacing is 2.978 (1) . The crystal structure is consolidated by extended relatively weak O—H...O hydrogen bonding with O...O distances ranging from 2.808 (4) to 3.276 (5) .
4-(Dimethylamino)pyridinium trans-diaquabis[oxalato(2−)-κ2O1,O2]chromate(III)
Justin Nenwa,Michel M. Belombe,Jean Ngoune,Boniface P. T. Fokwa
Acta Crystallographica Section E , 2010, DOI: 10.1107/s1600536810040353
Abstract: In the title salt, (C7H11N2)[Cr(C2O4)2(H2O)2], the asymmetric unit contains one half-cation and one half-anion. The Cr atom, the C and N atoms involved in C— N(exocyclic) bonding and the N and H atoms of N—H groups lie on twofold rotation axis. The CrIII atom of the complex anion is six-coordinated in a distorted (4 + 2) octahedral geometry with four equatorial O atoms of two nearly coplanar oxalate and two quasi-axial aqua O atoms. In the crystal, the protonated N atoms of the pyridine rings are hydrogen bonded to the carbonyl O atoms of the anions, forming chains along [010]. These chains are connected by lateral O—H...O hydrogen bonds, stabilizing the structure.
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