Kinetics of electroreduction of glycinate complexes of palladium(II) on the dropping mercury electrode

Kinetics and mechanism of electroreduction of Pd(II) complexes

“…the reduction of glycine complexes of Pd(II) was increasingly inhibited in the series F -< < Cl . The inhibition was also observed in alkaline solutions [19].…”

“…The fact that the limiting diffusion current I d was proportional to ω 1/2 and c Pd(II) (at c Pd(II) = 5 × 10 -4 -4 × 10 -3 M) testified that the process of the reduction of glycinate complexes of Pd(II) was the major factor that contributed to the observed values of I d [22]. The half-wave potentials E 1/2 , which were determined for the reduction of glycinate complexes of Pd(II) on RDPE in alkaline solutions of pH 9-11 in the presence of 0.5 M NaF and NaClO 4 differed from one another by no more than 0.02 V [22] and they differed by ~0.2 V on DME [19]. Similar results were obtained with acidic solutions.…”

“…k k log uted in [19] to the participation in the electrochemical step of specifically adsorbed complexes Pd(gly) 2 , which positioned themselves in parallel to the surface of the mercury electrode, as did glycine molecules adsorbed on mercury [36].…”

“…at the charges that corresponded to the specific adsorption of the and Cl anions on mercury [37][38][39]. As was assumed in [19], the specific adsorption of the and Cl anions hindered the stretching of the bonds between Pd(II) and the glycinate ion, which precedes the electron transport towards specifically adsorbed complexes, which hinders the cathodic process of their reduction. The and Cl anions exert a similar hindering effect on the process of reduction of chelate complexes Pd(ala) 2 [22] and Pd(ida [23], where alais the anion of α-alanine and ida 2is the anion of iminodiacetic acid.…”

“…In contrast to the reduction of relatively labile complexes Pd and Pd , processes of reduction of inert Pd(II) complexes containing ammonia [11][12][13][14], ethylenediamine [15][16][17], glycine [18][19][20][21], α -alanine [21,22], or anions of iminodiacetic acid [23] occur without preceding chemical steps. Below we will dis- cuss the kinetics and mechanism of reduction of a variety of Pd(II) complexes on DME and a Pd electrode.…”