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Papers by dr.devajani boruah
ChemInform, Aug 13, 2015
ABSTRACT Three rhodium(I) complexes of the types [Rh(COE)Cl(η2-L)] (1a,1b) and [RhCl(η2-L) (η1-L)... more ABSTRACT Three rhodium(I) complexes of the types [Rh(COE)Cl(η2-L)] (1a,1b) and [RhCl(η2-L) (η1-L)] (1c), where L = P∼N donor ligands 2-[2-(diphenylphosphino) ethyl]pyridine, (PPh2Etpy) (a), 2-(diphenylphosphino)pyridine (PPh2py) (b), and 3-(diphenylphosphino)-1-propylamine (PPh2(CH2)3NH2) (c), have been synthesized by reacting [Rh(coe)2Cl]2 with the respective ligands in 1:2 molar ratio for 1a, 1b and 1:4 molar ratio for 1c in DCM under refluxing condition. The complexes were characterized using different analytical techniques such as FT-IR, ESI(+) mass spectrometry, 1H and 31P{1H} NMR spectrometry, conductivity measurements, and melting point determination. The synthesized complexes were found to exhibit good catalytic activity for the transfer hydrogenation of carbonyl compounds to corresponding alcohols with high conversion rate. © 2015 Korean Chemical Society, Seoul & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
Abstract- The interactions of transition metals cobalt(II) and nickel(II) ions with the amino aci... more Abstract- The interactions of transition metals cobalt(II) and nickel(II) ions with the amino acids L-threonine(L-thr), L-proline(L-pro) and L-lysine(L-lys) in aqueous solution have been studied by using visible spectroscopic method. On addition of amino acids to the aqueous solution of the metal ions, a change in the visible spectra is observed due to the replacement of the water molecules from the coordination sphere of the aquocomplex [M(H2O)6] 2+ by the amino acid molecules. [M(H2O)6] 2+ + L = [M(H2O)5L] 2+ + H2O
![Research paper thumbnail of Ruthenium(II), rhodium(I) and iridium(I) complexes with [ p -(N,N-dimethylamino) phenyl]diphenylphosphine ligand: Synthesis, characterization and rhodium-catalysed carbonylation of methanol](https://attachments.academia-assets.com/80239640/thumbnails/1.jpg)
](refluxing/stirring under N2 affords neutral, mononuclear complexes, viz., trans-[RuCl2{η 1 -(P)-P... more refluxing/stirring under N2 affords neutral, mononuclear complexes, viz., trans-[RuCl2{η 1 -(P)-PPh2(p-C6H4NMe2)}2(PPh3)2], [Rh(coe)2Cl{η 1 -(P)PPh2(p-C6H4NMe2)}] and [Ir(cod)Cl{η 1 -(P)PPh2(p-C6H4NMe2)}] respectively. The complexes are characterized by elemental analysis, ESI(+)MS, UV-vis, conductivity measurements, cyclic voltammetry, thermal analysis and 1 H and 31 P{ 1 H}NMR studies. The catalytic efficiency of the rhodium complex for the carbonylation of methanol to acetic acid and its ester is evaluated at varying CO pressure (15, 20, 33 bar) at 130 °C. Under similar experimental conditions, these catalysts have a higher turnover number (1266-1896) than the well-known Monsanto’s species [Rh(CO)2I2] – (TON = 463-1000)
The interactions of transition metals cobalt(II) and nickel(II) ions with the amino acids L-threo... more The interactions of transition metals cobalt(II) and nickel(II) ions with the amino acids L-threonine(L-thr), Lproline(L-pro) and L-lysine(L-lys) in aqueous solution have been studied by using visible spectroscopic method. On addition of amino acids to the aqueous solution of the metal ions, a change in the visible spectra is observed due to the replacement of the water molecules from the coordination sphere of the aquocomplex [M(H2O)6] 2+ by the amino acid molecules. [M(H2O)6] 2+ + L = [M(H2O)5L] 2+ + H2O (where M = Co(II) and Ni(II); L = L-thr, L-pro and L-lys). The equilibrium constants and the change of Gibbs free energy ∆G o of the water exchange process at room temperature have been determined. For Ni(II)-H2O-amino acid systems the equilibrium constants have been determined for five variable temperatures (318-298 K) and the corresponding thermodynamic parameters ∆G o , ∆H o and ∆S o have been calculated.
The reaction of RuCl2(PPh3)3 with two molar equivalents of a multi-functionalized ligand, 3-diphe... more The reaction of RuCl2(PPh3)3 with two molar equivalents of a multi-functionalized ligand, 3-diphenylphosphino-1propylamine (DPPA) yields two mononuclear, low spin, diamagnetic, octahedral neutral complexes, [RuCl2(η -P,NDPPA)2] (1) and [RuCl2(η -P,N-DPPA)(PPh3)2] (2). The complexes have been characterized by conductivity measurements, FTIR, UV-vis, H and variable temperature P{H} NMR, ESI(+)MS, TGA-DTG and cyclic voltammetry. The ESI(+) mass spectrogram of (1) shows molecular ion peak at m/z 658[M], indicating mononuclear nature of the complex . No fluxional behavior is observed from the variable temperature (200-300 K) P{H} NMR spectra. The complexes (1) and (2) upon treatment with CH3CN in 1:1 molar ratio in the presence of NH4PF6 in dichloromethane solution afford the six-coordinate cationic complexes [RuCl(η-P,N-DPPA)2(CH3CN)](PF6) (3) and [RuCl(η -P,N-DPPA)(CH3CN)(PPh3)2](PF6) (4), respectively. The complexes (3) and (4) have also been characterized by FTIR, ESI(+)MS, H and P{H...
Bulletin of the Korean Chemical Society, Apr 1, 2015
Applied Organometallic Chemistry, 2013
ABSTRACT The reaction of N‐methylimidazole (N‐MeIm) and N‐butylimidazole (N‐BuIm) with the comple... more ABSTRACT The reaction of N‐methylimidazole (N‐MeIm) and N‐butylimidazole (N‐BuIm) with the complexes [PdCl2(PPh2py–P,N)] and [PdCl2(PPh2Etpy–P,N)] in the presence of NH4PF6 under N2 at room temperature afforded four new cationic Pd(II) complexes [PdCl(PPh2py–P,N)(N‐MeIm)](PF6) (1), [PdCl(PPh2py–P,N)(N‐BuIm)](PF6) (2), [PdCl(PPh2Etpy–P,N)(N‐MeIm)](PF6) (4) and [PdCl(PPh2Etpy‐P,N)(N‐BuIm)](PF6) (5) in good yields, where PPh2py is 2‐(diphenylphosphino)pyridine and PPh2Etpy is 2‐{2‐(diphenylphosphino)ethyl}pyridine). The complexes were fully characterized. The catalytic activities of these complexes were investigated for Suzuki–Miyaura cross‐coupling reactions at room temperature. Complex 2 exhibited excellent activity compared to other analogs. Copyright © 2013 John Wiley & Sons, Ltd.
ChemInform, Aug 13, 2015
ABSTRACT Three rhodium(I) complexes of the types [Rh(COE)Cl(η2-L)] (1a,1b) and [RhCl(η2-L) (η1-L)... more ABSTRACT Three rhodium(I) complexes of the types [Rh(COE)Cl(η2-L)] (1a,1b) and [RhCl(η2-L) (η1-L)] (1c), where L = P∼N donor ligands 2-[2-(diphenylphosphino) ethyl]pyridine, (PPh2Etpy) (a), 2-(diphenylphosphino)pyridine (PPh2py) (b), and 3-(diphenylphosphino)-1-propylamine (PPh2(CH2)3NH2) (c), have been synthesized by reacting [Rh(coe)2Cl]2 with the respective ligands in 1:2 molar ratio for 1a, 1b and 1:4 molar ratio for 1c in DCM under refluxing condition. The complexes were characterized using different analytical techniques such as FT-IR, ESI(+) mass spectrometry, 1H and 31P{1H} NMR spectrometry, conductivity measurements, and melting point determination. The synthesized complexes were found to exhibit good catalytic activity for the transfer hydrogenation of carbonyl compounds to corresponding alcohols with high conversion rate. © 2015 Korean Chemical Society, Seoul & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
Abstract- The interactions of transition metals cobalt(II) and nickel(II) ions with the amino aci... more Abstract- The interactions of transition metals cobalt(II) and nickel(II) ions with the amino acids L-threonine(L-thr), L-proline(L-pro) and L-lysine(L-lys) in aqueous solution have been studied by using visible spectroscopic method. On addition of amino acids to the aqueous solution of the metal ions, a change in the visible spectra is observed due to the replacement of the water molecules from the coordination sphere of the aquocomplex [M(H2O)6] 2+ by the amino acid molecules. [M(H2O)6] 2+ + L = [M(H2O)5L] 2+ + H2O
refluxing/stirring under N2 affords neutral, mononuclear complexes, viz., trans-[RuCl2{η 1 -(P)-P... more refluxing/stirring under N2 affords neutral, mononuclear complexes, viz., trans-[RuCl2{η 1 -(P)-PPh2(p-C6H4NMe2)}2(PPh3)2], [Rh(coe)2Cl{η 1 -(P)PPh2(p-C6H4NMe2)}] and [Ir(cod)Cl{η 1 -(P)PPh2(p-C6H4NMe2)}] respectively. The complexes are characterized by elemental analysis, ESI(+)MS, UV-vis, conductivity measurements, cyclic voltammetry, thermal analysis and 1 H and 31 P{ 1 H}NMR studies. The catalytic efficiency of the rhodium complex for the carbonylation of methanol to acetic acid and its ester is evaluated at varying CO pressure (15, 20, 33 bar) at 130 °C. Under similar experimental conditions, these catalysts have a higher turnover number (1266-1896) than the well-known Monsanto’s species [Rh(CO)2I2] – (TON = 463-1000)
The interactions of transition metals cobalt(II) and nickel(II) ions with the amino acids L-threo... more The interactions of transition metals cobalt(II) and nickel(II) ions with the amino acids L-threonine(L-thr), Lproline(L-pro) and L-lysine(L-lys) in aqueous solution have been studied by using visible spectroscopic method. On addition of amino acids to the aqueous solution of the metal ions, a change in the visible spectra is observed due to the replacement of the water molecules from the coordination sphere of the aquocomplex [M(H2O)6] 2+ by the amino acid molecules. [M(H2O)6] 2+ + L = [M(H2O)5L] 2+ + H2O (where M = Co(II) and Ni(II); L = L-thr, L-pro and L-lys). The equilibrium constants and the change of Gibbs free energy ∆G o of the water exchange process at room temperature have been determined. For Ni(II)-H2O-amino acid systems the equilibrium constants have been determined for five variable temperatures (318-298 K) and the corresponding thermodynamic parameters ∆G o , ∆H o and ∆S o have been calculated.
The reaction of RuCl2(PPh3)3 with two molar equivalents of a multi-functionalized ligand, 3-diphe... more The reaction of RuCl2(PPh3)3 with two molar equivalents of a multi-functionalized ligand, 3-diphenylphosphino-1propylamine (DPPA) yields two mononuclear, low spin, diamagnetic, octahedral neutral complexes, [RuCl2(η -P,NDPPA)2] (1) and [RuCl2(η -P,N-DPPA)(PPh3)2] (2). The complexes have been characterized by conductivity measurements, FTIR, UV-vis, H and variable temperature P{H} NMR, ESI(+)MS, TGA-DTG and cyclic voltammetry. The ESI(+) mass spectrogram of (1) shows molecular ion peak at m/z 658[M], indicating mononuclear nature of the complex . No fluxional behavior is observed from the variable temperature (200-300 K) P{H} NMR spectra. The complexes (1) and (2) upon treatment with CH3CN in 1:1 molar ratio in the presence of NH4PF6 in dichloromethane solution afford the six-coordinate cationic complexes [RuCl(η-P,N-DPPA)2(CH3CN)](PF6) (3) and [RuCl(η -P,N-DPPA)(CH3CN)(PPh3)2](PF6) (4), respectively. The complexes (3) and (4) have also been characterized by FTIR, ESI(+)MS, H and P{H...
Bulletin of the Korean Chemical Society, Apr 1, 2015
Applied Organometallic Chemistry, 2013
ABSTRACT The reaction of N‐methylimidazole (N‐MeIm) and N‐butylimidazole (N‐BuIm) with the comple... more ABSTRACT The reaction of N‐methylimidazole (N‐MeIm) and N‐butylimidazole (N‐BuIm) with the complexes [PdCl2(PPh2py–P,N)] and [PdCl2(PPh2Etpy–P,N)] in the presence of NH4PF6 under N2 at room temperature afforded four new cationic Pd(II) complexes [PdCl(PPh2py–P,N)(N‐MeIm)](PF6) (1), [PdCl(PPh2py–P,N)(N‐BuIm)](PF6) (2), [PdCl(PPh2Etpy–P,N)(N‐MeIm)](PF6) (4) and [PdCl(PPh2Etpy‐P,N)(N‐BuIm)](PF6) (5) in good yields, where PPh2py is 2‐(diphenylphosphino)pyridine and PPh2Etpy is 2‐{2‐(diphenylphosphino)ethyl}pyridine). The complexes were fully characterized. The catalytic activities of these complexes were investigated for Suzuki–Miyaura cross‐coupling reactions at room temperature. Complex 2 exhibited excellent activity compared to other analogs. Copyright © 2013 John Wiley & Sons, Ltd.