Synthesis and Characterization of Rhodium Complexes Containing 2,4,6-Tris(2-pyridyl)-1,3,5-triazine and Its Metal-Promoted Hydrolytic Products: Potential Uses of the New Complexes in Electrocatalytic
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- 作者：Parimal Paul ; Beena Tyagi ; Anvarhusen K. Bilakhiya ; Mohan M. Bhadbhade ; Eringathodi Suresh ; and G. Ramachandraiah
- 刊名：Inorganic Chemistry
- 出版年：1998
- 出版时间：November 2, 1998
- 年：1998
- 卷：37
- 期：22
- 页码：5733 - 5742
- 全文大小：144K
- 年卷期：v.37,no.22(November 2, 1998)
- ISSN：1520-510X
文摘
The reaction of 2,4,6-tris(2-pyridyl)-1,3,5-triazine (tptz) with RhCl3·3H2O has been studied under differentexperimental conditions. This reaction in ethanol resulted in the formation of [Rh(tptz)Cl3]·2H2O (1), whereasthe bis-chelate complex [Rh(tptz)2][ClO4]3·2H2O (2) was obtained in a two-step reaction in acetone; the chloridesfrom RhCl3 were removed in the first step using AgClO4, and the ligand tptz was added in the second step.Complexes 1 and 2, when refluxed in ethanol-water (1:1), resulted in metal-promoted hydrolysis of tptz to bis(2-pyridylcarbonyl)amide anion (bpca) and 2-picolinamide (pa), yielding the complexes [Rh(bpca)(pa)Cl][PF6]·H2O (3) and [Rh(bpca)2][ClO4] (6), respectively. A mixed-ligand complex, [Rh(bpca)(tpy)][PF6]2·CH3CN (4),was obtained by the reaction of either 1 with tpy or [Rh(tpy)Cl3] (5) with tptz in ethanol-water medium. Thecrystal structures of complexes 1 and 4 have been determined. Crystal data: complex 1, monoclinic, P21/c, a =11.642(2) Å, b = 7.302(2) Å, c = 24.332(3) Å, 
= 96.420(10)
, Z = 4, R = 0.040, and wR2 = 0.117; complex4, triclinic, P
, a = 9.581(1) Å, b = 12.933(2) Å, c = 14.493(2) Å, 
= 82.480(10), = 71.810(10), 
=75.100(10), Z = 2, R = 0.030, and wR2 = 0.082. The two water molecules of complex 1 make short contactswith the carbon atoms adjacent to the metal-bound nitrogen atom of the triazine ring; this observation providessome insight about the "intermediate" of the hydrolysis. X-ray and NMR data suggest that the electron-withdrawingeffect of the metal ion is the major responsible factor for the hydrolysis of tptz. The cyclic voltammograms ofthe complexes exhibit a metal-based 2e reduction (Rh(III) 
Rh(I)) at the potential range -0.42 to -0.98 V vsSCE, followed by ligand-based redox couple(s). These novel complexes show effective catalytic properties forthe electrocatalytic reduction of carbon dioxide in the potential range -1.26 to -1.44 V.
= 96.420(10), Z = 4, R = 0.040, and wR2 = 0.117; complex4, triclinic, P, a = 9.581(1) Å, b = 12.933(2) Å, c = 14.493(2) Å, = 82.480(10), = 71.810(10), =75.100(10), Z = 2, R = 0.030, and wR2 = 0.082. The two water molecules of complex 1 make short contactswith the carbon atoms adjacent to the metal-bound nitrogen atom of the triazine ring; this observation providessome insight about the "intermediate" of the hydrolysis. X-ray and NMR data suggest that the electron-withdrawingeffect of the metal ion is the major responsible factor for the hydrolysis of tptz. The cyclic voltammograms ofthe complexes exhibit a metal-based 2e reduction (Rh(III) Rh(I)) at the potential range -0.42 to -0.98 V vsSCE, followed by ligand-based redox couple(s). These novel complexes show effective catalytic properties forthe electrocatalytic reduction of carbon dioxide in the potential range -1.26 to -1.44 V.