Syntheses, Characterization and X-ray Crystal Structure of Polymeric Heteronuclear Oxo-bridged Fe/Na Assembled with Salen-type Schiff Base and Dicyanamide
Popa Haba,
Mouhamadou Moustapha Sow,
Mamour Sarr,
Ibrahima Elhadji Thiam,
Mahy Diaw,
Mohamed Lamine Gaye
Issue:
Volume 8, Issue 2, April 2020
Pages:
20-27
Received:
6 March 2020
Accepted:
23 March 2020
Published:
17 April 2020
Abstract: Reaction of FeCl2.4H2O with 2-(-(2-(-2-hydroxy-3-methoxybenzylideneamino)phenylimino)methyl)-6-methoxyphenol (H2L) gives the metalloligand [Fe(L)].(H2O) (1). Reaction of metalloligand (1) with three fold of sodium dicyanamide Na[N(CN)2] gives the new tetranuclear compound [{FeIINaI(L)(EtOH)(HN(CN)2)}(μ-O){FeIIINaI(L)(NO3)]}]n (2) in which one of the two irons is oxidized to +3. Suitable crystals of (2) were grown by slow evaporation of ethanol solution during two weeks. The metalloligand (1) and the tetranuclear (2) complexes are characterized by IR and physical measurement. Spectroscopic evidence indicated that the Schiff base H2L behave an N2O2O’2 coordination tetradentate ligand. The structure of (2) was elucidated by X-ray diffraction analysis. The asymmetric unit of the compound contains two dideprotonated ligand molecules, two iron ions, one hexacoordinated sodium ion, one heptacoordinated sodium ion, one bidentate nitrate group, one monodentate dicyanamide unit, one coordinated ethanol molecule and an O2- ion which acts as a bridge between the FeII and the FeIII of two entities: [FeIINaI(L)(EtOH)(HN(CN)2)] and [FeIIINaI(L)(NO3)]. Bridge Fe—O(μ) bond lengths are 1.7813(14) and 1.7856(13) Å and bridging angle Fe—O—Fe is 144.78(8)°. The second terminal cyano group of the dicyanamide link another molecule complex through the heptacoordinated NaI leading a polymeric structure. Intermolecular hydrogen bond connect the polymeric chains to develop a three dimensional structure.
Abstract: Reaction of FeCl2.4H2O with 2-(-(2-(-2-hydroxy-3-methoxybenzylideneamino)phenylimino)methyl)-6-methoxyphenol (H2L) gives the metalloligand [Fe(L)].(H2O) (1). Reaction of metalloligand (1) with three fold of sodium dicyanamide Na[N(CN)2] gives the new tetranuclear compound [{FeIINaI(L)(EtOH)(HN(CN)2)}(μ-O){FeIIINaI(L)(NO3)]}]n (2) in which one of th...
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Review on In-depth Analysis of the Passive Films of W-xTi Alloys by Angle Resolved X-Ray Photoelectron Spectroscopy
Issue:
Volume 8, Issue 2, April 2020
Pages:
28-35
Received:
29 February 2020
Accepted:
16 March 2020
Published:
28 April 2020
Abstract: Spontaneously passivated sputter-deposited W-22Ti and W-58Ti alloys showed higher corrosion resistance than those of tungsten and titanium metals in 12 M HCl solution open to air at 30°C. Average corrosion rates of W-(22-58)Ti alloys (that is, about 9.5-18.5 × 10-3 mm/y) were found to be about three and half orders of magnitude lower than titanium and even lower than that of tungsten metal. Such synergistic effect of the simultaneous additions of tungsten and titanium in the extremely high corrosion resistance properties of the sputter-deposited amorphous/nanocrystalline W-xTi alloys was investigated using angle resolved X-ray photoelectron spectroscopic (ARXPS) analyses. In-depth surface analyses of the thin passive films of the W-xTi alloys using angle resolved XPS analyses revealed that the high corrosion resistance of the amorphous/nanocrystalline W-xTi alloys is mostly due to the formation of homogeneous passive double oxyhydroxide films consisting of Wox and Ti4+ cations without any concentration gradient in-depth in 12 M HCl solution at 30°C. Consequently, titanium metal acts synergistically with tungsten in enhancing the spontaneous passivity as well as the high corrosion resistance of the sputter-deposited binary W-xTi alloys.
Abstract: Spontaneously passivated sputter-deposited W-22Ti and W-58Ti alloys showed higher corrosion resistance than those of tungsten and titanium metals in 12 M HCl solution open to air at 30°C. Average corrosion rates of W-(22-58)Ti alloys (that is, about 9.5-18.5 × 10-3 mm/y) were found to be about three and half orders of magnitude lower than titanium ...
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Aerobic Oxidation of Cyclopentane by Using Fluorinated N-Hydroxyphthalimide Derivatives
Samar Kumar Guha,
Yasutaka Ishii
Issue:
Volume 8, Issue 2, April 2020
Pages:
36-41
Received:
3 March 2020
Accepted:
7 April 2020
Published:
28 April 2020
Abstract: N-Hydroxyphthalimide derivatives, F15- and F17-NHPI, bearing fluorinated carboxylate and alkyl chains, respectively, were prepared and their catalytic performances were compared with those of N-hydroxyphthalimide (NHPI). Thus, the oxidation of cyclopentane under 10 atm of air in the presence of catalytic amount of fluorinated NHPI or NHPI, Co(OAc)2, and Mn(OAc)2 in TFT as solvent at 100°C afforded cyclopentanol, cyclopentanone, succinic acid and glutaric acid. It was assumed that F-NHPI derivatives bearing electron withdrawing fluorocarbon groups showed higher catalytic activity than the NHPI by enhancement of the electrophilicity of N-oxy radicals generated from the F-NHPI derivatives. In the oxidation of cyclopentane, F-NHPI showed better catalytic activity than NHPI. Cyclopentanol and glutaric acid were obtained as the major products in case of NHPI, whereas, cyclopentanone and glutaric acid were obtained as the major products in case of fluorinated NHPIs. However, only glutaric acid was obtained as the major product when a increased amount of Co(OAc)2 was used in the present ocidation by using NHPI or F-NHPIs. The effect of temperature and air was also investigated in the oxidation of cyclopentane. When the oxidation was performed at 90°C, cyclopentanol was obtained as the major product, whereas, no significant changes were observed when the reaction was performed at 20 atm instead of 10 atm. The great advantage of the fluorinated NHPI derivatives is that it could be recovered after the oxidation.
Abstract: N-Hydroxyphthalimide derivatives, F15- and F17-NHPI, bearing fluorinated carboxylate and alkyl chains, respectively, were prepared and their catalytic performances were compared with those of N-hydroxyphthalimide (NHPI). Thus, the oxidation of cyclopentane under 10 atm of air in the presence of catalytic amount of fluorinated NHPI or NHPI, Co(OAc)2...
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