Browsing by Author "Eke, Uche B."
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Item Hexakis(benzonitrile)ruthenium(II) bis[tetrafluoroborate(1-)]: a precursor to ruthenium organometallic compounds(Springer, 2015-11-14) Owalude, Samson O.; Odebunmi, Ezekiel O.; Eke, Uche B.; Tella, Adedibu C.; Rheingold, Arnold L.; Jackson, Randy; Suib, Steven L.The new compound, [Ru(NCC6H5)6][BF4]2, has been synthesized by reaction of the polymeric species [{RuCl2(COD)}x] (COD = 1,5-cyclooctadiene) with benzonitrile under reflux and characterized by elemental analysis, IR, NMR spectroscopic analyses, and single crystal X-ray diffraction. The Ru(II) atom is coordinated by six N atoms from six benzonitrile ligands in distorted octahedralc oordination geometry. The compound was crystallized in the monoclinic space group P21/c with unit-cell dimensions a = 10.7536(11) A ° , b = 18.6582(18) A °, c = 20.311(2) A ° , b = 91.864(2) , V = 4073.2(7) A ° 3 and final R of 0.0429.Item Solvent-free mechanochemical synthesis and X-ray studies of Cu(II) and Ni(II) complexes of 5-(3,4,5-Trimethoxybenzyl)pyrimidine-2,4-diamine (Trimethoprim) in a ball-mill(Elsevier B.V., 2016-02-10) Tella, Adedibu C.; Eke, Uche B.; Owalude, Samson O.Solvent-free synthesis of [Cu(CH3COO)2(TMP)2](1) and [Ni(CH3COO)2(TMP)2](2) by ball milling of Cu(CH3COO)2.H2O and Ni(CH3COO)2.4H2O with Trimethoprim in the absence of solvent is described. Conventional synthesis of 1. CH3OH and 2.CH3OH was carried out by the reaction of metal acetate salt and Trimethoprim using the solution-based method (reflux in CH3OH for 2 h) for comparison purposes. The mechanochemical products were characterized by comparison of melting points, conductivity values, spectral data, XRPD patterns with those of free ligand and solution based conventional synthesis products. X-ray diffraction patterns of the complex were similar to the simulated pattern of the complex obtained from single crystal structure suggesting the formation of identical compounds as obtained in solvent medium. The process presented here is operationally simple, environmentally benign and affords excellent yields without the need for solvents or external heating. Clearly, it can present a higher efficiency in terms of materials, energy and time compared to classical solution phase synthesis.Item Spectral studies of transition metal complexes ofdihydrobis(1-pyrazoyl)borate with some Lewis bases(Elsevier B.V., 2016-05-12) Mesubi, Adediran M.; Eke, Uche B.; Oyeku, Oyedele M.; Owalude, Samson O.Co(II), Ni(II) and Cu(II) complexes of dihydrobis(1-pyrazolyl)borate and their adducts with some Lewis bases have been prepared and characterized by elemental analyses, IR and UV–vis spectroscopic techniques. The adducts were either 1:1 or 1:2 complexes depending on whether the Lewis base was bidentate or monodentate. The results indicate that adducts with 1,10-phenanthroline were the most stable due to the chelating effect of the Lewis base. The order of reactivity of the complexes was determined to be Ni(H2BPz2)2 > Cu(H2BPz2)2 > CoH2(BPz2)2 > Co(H2BPz2)2. The effects of various solvents (i.e., benzene, chloroform and DMF) on the structure were studied. The solvents appear to minimally affect the visible spectra of Co(H2BPz2)2. The Ni(H2BPz2)2 and Cu(H2BPz2)2 adducts exhibit a four-coordinate structure in non-coordinating solvents. However, in coordinating solvents, such as DMF, the adducts exhibit six-coordinate structures.Item Syntheses and X-ray crystal structures of two ruthenium(II) complexes derived from acetonitrile and dimethylphenylphosphonite(Elsevier B.V., 2013-04-10) Owalude, Samson O.; Odebunmi, Ezekiel O.; Eke, Uche B.; Rheingold, Arnold L.; Opembe, Naftali; Suib, Steven L.The ruthenium acetonitrile complex [RuCl2(NCCH3)2{P(OCH3)2C6H5}2] (1) and the stable salt [Ru(CH3CN)4{P(OCH3)2C6H5}2][BF4]2 (2) have been prepared from [RuCl2(NCCH3)2(COD)] and the salt [Ru(COD)(CH3CN)4][BF4]2 respectively. The two compounds have been characterized by IR, microanalytical, NMR measurements and single-crystal X-ray diffraction studies. The ruthenium in both compounds has almost ideal octahedral coordination geometry. One of the complexes, [RuCl2{P(OCH3)2C6H5}2(NCCH3)2] (1) has shown significant catalytic activity for the transfer hydrogenation of simple ketones while the other, [Ru{P(OCH3)2C6H5}2(NCCH3)4][BF4]2 (2) did not show any catalytic activity for this reaction.Item The Synthesis and Structure of Hexakis(dimethylphenylphosphonite)ruthenium(II) bis[tetraphenylborate(–1)](WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim, 2014-02-12) Owalude, Samson O.; Odebunmi, Ezekiel O.; Eke, Uche B.; Tella, Adedibu C.; Rheingold, Arnold L.; Suib, Steven L.Treatment of the hydrazine salt [Ru(COD)(H2NNH2)4][BPh4]2 with excess of P(OMe)2Ph in acetone gave a homoleptic complex trans-[Ru{P(OMe)2Ph}6][BPh4]2, which was characterized by IR, 31P{1H}, 13C{1H}, and 1H NMR spectroscopy, elemental analysis, and X-ray crystallography. The ruthenium in the complex has distorted octahedral coordination arrangement and bonded to all the six P(OMe)2Ph molecules through the phosphorus atoms.Item Synthesis and X-ray studies of ruthenium(II) complexes containing hydrazine and benzyl isocyanide ligands(Chemical Society of Ethiopia, 2013-07-24) Owalude, Samson O.; Odebunmi, Ezekiel O.; Eke, Uche B.; Meijboom, Reinout; Nesterov, Vladimir N.; Singleton, Eric; Coville, Neil J.The reaction of the polymeric species [{RuCl2(COD)}x] (1 ; x > 2; COD = cyclo-octa-1,5-diene) and hydrazine hydrate in methanol under reflux gave a pale pink solution from which the salt [Ru(COD)(N2H4)4][BPh4]2.CH3OH (2) was isolated on addition of NaBPh4. Treatment of 2 in refluxing acetone in the presence of the ligand benzyl isocyanide give a complex of stoichiometry [Ru(NH2N=CMe2)2(PhCH2NC)4][BPh4]2 (3) on the substitution of the labile COD ligand. The two compounds have been characterized by elemental analyses, IR and NMR measurements and single-crystal X-ray diffraction studies. The ruthenium in both compounds has a distorted octahedral coordination geometry.Item Synthesis of new ruthenium(II) complexes derived from labile nitrile ligands: an alternative route to the preparation of transdichlorotetrakis(diphenylphosphine)ruthenium(II)(Taylor and Francis, UK., 2017-03-19) Owalude, Samson O.; Tella, Adedibu C.; Odebunmi, Ezekiel O.; Eke, Uche B.; Golen, James E.; Rheingold, Arnold L.; Mahlaka, Thabo Joel; Meijboom, ReinoutNew ruthenium(II) complexes containing labile nitrile ligands have been prepared by treatment of either the polymer [{RuCl2(COD)}x] (COD = cycloocta-1,5-diene) (1) or its derivative [RuCl2(COD)(NCCH3)2]·NCCH3 (2) with the appropriate nitrile ligands in refluxing acetonitrile under argon. A new route to synthesis of trans-dichlorotetrakis(diphenylphosphine)ruthenium(II) (7) was also reported. A redetermination of the structure of 7 was undertaken and X-ray crystallographic data revealed that the complex crystallizes in the triclinic space group P-1 with unit cell dimensions a = 12.7016(9) Å, b = 13.0847(10) Å, c = 14.1498(10) Å, α = 101.46(3)°, V = 2080.6(3) Å3, Z = 2 and R = 0.0309. Its polymorph 7′ was also obtained. The crystal structure of 4 was also determined. This complex crystallizes in the monoclinic space group C2/c with unit cell dimensions a = 27.0510(3) Å, b = 11.0984(13) Å, c = 13.0450(16) Å, α = 90°, V = 3886.5(8) Å3, Z = 8 and R = 0.0282.