Methyl Iodide Oxidative Addition to Rhodium(I) Complexes: a DFT and NMR Study of [Rh(FcCOCHCOCF3)(CO)(PPh3)] and the Rhodium(III) Reaction Products

A theoretical (DFT) study of the equilibrium geometry of the possible reaction products of the oxidative addition reaction [Rh(FcCOCHCOCF3)(CO)(PPh3)] + CH3I (Fc = ferrocenyl), consistent with experimental observations, revealed that the first alkyl product results from trans addition to RhI. Isomerization via an acyl intermediate leads to a second octahedral alkyl product with the PPh3 group and the iodide above and below the square plane. Theoretical computations also revealed that the thermodynamic acyl product adopts a square-pyramidal geometry with the COCH3 group in the apical position.Keywords: DFT, computational, rhodium, β-diketone, NMRPDF and Supplementry file attache

Jahn-Teller distortion in 2-pyridyl-(1,2,3)-triazole-containing copper(ii) compounds

© The Royal Society of Chemistry and the Centre National de la Recherche Scientifique. The syntheses, characterization and experimental solid state X-ray structures of five low-spin paramagnetic 2-pyridyl-(1,2,3)-triazole-copper compounds, [Cu(Ln)2Cl2], are presented in this study, for the following five Lnligands: L1= 2-(1-(p-tolyl)-1H-(1,2,3-triazol-4-yl)pyridine), L2= 2-(1-(4-chlorophenyl)-1H-(1,2,3-triazol-4-yl)pyridine), L3= 4-(4-(pyridin-2-yl)-1H-(1,2,3-triazol-4-yl)benzonitril), L4= 2-(1-phenyl-1H-(1,2,3-triazol-4-yl)pyridine) and L5= 2-(1-(4-(trifluoromethyl)phenyl)-1H-(1,2,3-triazol-4-yl)pyridine). These five [Cu(Ln)2Cl2] complexes each contain two bidentate 2-pyridyl-(1,2,3)-triazole (Ln) and two chloride ions as ligands, with the Cu-N(pyridine) bonds, Cu-N(triazole) and Cu-Cl bonds trans to each other. All five [Cu(Ln)2Cl2] compounds display elongation Jahn-Teller distortion, either along opposite Cu-N(triazole) bonds, or along opposite Cu-Cl bonds, as indicated by their obtained solid state crystal structures. Quantum chemistry calculations, using density functional theory, indicated however that elongation Jahn-Teller distortion is in fact possible along any two opposite bonds in these octahedral compounds with the elongation distortion along the opposite Cu-N(triazole) bonds being the most stable structure

Novel dichloro(bis{2-[1-(4-methylphenyl)-1H-1,2,3-triazol-4-yl-κN3]pyridine-κN})metal(II) coordination compounds of seven transition metals (Mn, Fe, Co, Ni, Cu, Zn and Cd)

© 2018 Elsevier Ltd. The synthesis, characterization, DFT and, in two cases, the structure of seven novel dichloro(bis{2-[1-(4-methylphenyl)-1H-1,2,3-triazol-4-yl-κN3]pyridine-κN})metal(II) coordination compounds ([M(L2)2Cl2]), containing transition metals of groups 7–12, are described. Both experimentally measured magnetic moment and DFT calculations showed that d5Mn(II) (with µeff= 5.62 B.M., S = 5/2), d6Fe(II) (with µeff= 5.26 B.M., S = 2), d7Co(II) (with µeff= 3.98 B.M., S = 3/2), d8Ni(II) (with µeff= 3.00 B.M., S = 1) and d9Cu(II) (with µeff= 1.70 B.M., S = ½) are all paramagnetic, while d10Zn(II) and Cd(II) are diamagnetic with S = 0. DFT calculations on the possible isomers of these coordination compounds, showed that the cis–cis–trans and the trans–trans–trans isomers, with the pyridyl groups trans to each other, are the lowest in energy. The trans–trans–trans isomers were experimentally characterized by X-ray crystallography for [Ni(L2)2Cl2] and [Zn(L2)2Cl2]·L2in this study. In the solid state the coordination compounds are connected by intermolecular hydrogen bonds, mainly involving the chloride atoms, to form 3D supramolecular structures. Computational chemistry calculations, using Natural Bonding Orbital calculations, identified these inter-molecular hydrogen bonds, C–H⋯Cl, by a donor–acceptor interaction from a filled lone pair NBO on Cl to an empty antibonding NBO on (C–H). The inter-molecular hydrogen bonds were also identified by QTAIM determined bonding paths between Cl and the respective hydrogen. The theoretically calculated computational chemistry results thus give an understanding on a molecular level why in the solid state where inter-molecular forces and packing play a role, the trans–trans–trans isomers are mostly obtained

Synthesis, characterization, experimental and theoretical structure of novel Dichloro(bis{2-[1-(4-methoxyphenyl)-1H-1,2,3-triazol-4-yl-κN3]pyridine-κN})metal(II) compounds, metal = Mn, Co and Ni

© 2018 Elsevier B.V. The syntheses, characterizations and structures of three novel dichloro(bis{2-[1-(4-methoxyphenyl)-1H-1,2,3-triazol-4-yl-κN 3 ]pyridine-κN})metal(II), [M(L) 2 Cl 2 ], complexes (metal = Mn, Co and Ni) are presented. In the solid state the molecules are arranged in infinite hydrogen-bonded 3D supramolecular structures, further stabilized by weak intermolecular π…π interactions. The DFT results for all the different spin states and isomers of dichloro(bis{2-[1-phenyl-1H-1,2,3-triazol-4-yl-κN 3 ]pyridine-κN})metal(II) complexes, [M(L 1 ) 2 Cl 2 ], support experimental measurements, namely that (i) d 5 [Mn(L 1 ) 2 Cl 2 ] is high spin with S = 5/2; (ii) d 7 [Co(L 1 ) 2 Cl 2 ] has a spin state of S = 3/2, (iii) d 8 [Ni(L 1 ) 2 Cl 2 ] has a spin state of S = 1; and (iv) for all [M(L 1 ) 2 Cl 2 ] and [M(L) 2 Cl 2 ] comple xes, with M = Mn, Co and Ni, the cis-cis-trans and the trans-trans-trans isomers, with the pyridyl groups trans to each other, have the lowest energy

Chemical and structural data of (1,2,3-triazol-4-yl)pyridine-containing coordination compounds

The data presented in this paper are related to the research article entitled “Novel dichloro(bis{2-[1-(4-methylphenyl)-1H-1,2,3-triazol-4-yl-κN3]pyridine-κN})metal(II) coordination compounds of seven transition metals (Mn, Fe, Co, Ni, Cu, Zn and Cd)” (Conradie et al., 2018) [1]. This paper presents characterization and structural data of the 2-(1-(4-methyl-phenyl)-1H-1,2,3-triazol-1-yl)pyridine ligand (L2) (Tawfiq et al., 2014) [2] as well as seven dichloro(bis{2-[1-(4-methylphenyl)-1H-1,2,3-triazol-4-yl-κN3]pyridine-κN})metal(II) coordination compounds, [M(L2)2Cl2], all containing the same ligand but coordinated to different metal ions. The data illustrate the shift in IR, UV/VIS, and NMR (for diamagnetic complexes) peaks when L is coordinated to the metals, as well as the influence of the different metals on the peak positions. Solid state structural data is presented for M = Ni and Zn, while density functional theory calculated energies, structures and optimized coordinates are provided for the lowest energy cis and trans conformations for L2 as well as [M(L2)2Cl2] with M = Mn, Fe, Co, Ni, Cu, Zn and Cd

Synthesis, characterisation and electrochemistry of eight Fe coordination compounds containing substituted 2-(1-(4-R-phenyl-1H-1,2,3-triazol-4-yl)pyridine ligands, R = CH3, OCH3, COOH, F, Cl, CN, H and CF3

© 2018 Elsevier B.V. Eight different Dichloro(bis{2-[1-(4-R-phenyl)-1H-1,2,3-triazol-4-yl-κN3]pyridine-κN})iron(II) compounds, 2–9, have been synthesised and characterised, where group R = CH3 (L2), OCH3 (L3), COOH (L4), F (L5), Cl (L6), CN (L7), H (L8) and CF3 (L9). The single crystal X-ray structure was determined for the L3 which was complemented with Density Functional Theory calculations for all complexes. The structure exhibits a distorted octahedral geometry, with the two triazole ligands coordinated to the iron centre positioned in the equatorial plane and the two chloro atoms in the axial positions. The values of the FeII/III redox couple, observed at ca. −0.3 V versus Fc/Fc+ for complexes 2–9, varied over a very small potential range of 0.05 V. The observation that the different R substituents have virtually no effect on the values of the FeII/III redox couple for all eight complexes 2–9, is explained by the character of the highest molecular orbitals of complexes 2–9, which do not show any communication of electron density between the various ligands and the metal Fe. However, the HOMOs of the free ligands L2 – L9, display extended π-character over the entire ligand, explaining the sensitivity of the 1H NMR C–H-triazole peak, which is dependent on the electron donating/withdrawing power of the R substituent attached to the 2-[1-(4-R-phenyl)-1H-1,2,3-triazol-4-yl]pyridine ligands

Bone geometry in Black and White South Arican females

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A comparative study of known determinants of bone strength in Black and White South African females

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A comparative study of the determinants of bone strength and the propensity to falls in Black and White South African women - a preliminary report on bone mineral density (BMD) and fracture prevalence

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BMD changes in osteoporotic patients treated for at least 3 years with intravenous Pamidronate Disodium

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