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Solvent control on the electron transfer reaction between Co III (en) 2 Br(L) 2+ –Fe(CN) 6 4− (L = aryl amines) by regression relationships: the PXRD and electrochemical investigations
Author(s) -
Anbalagan K.,
Lydia I. S.
Publication year - 2011
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.1700
Subject(s) - chemistry , aryl , solvent , monoclinic crystal system , crystallography , powder diffraction , electron transfer , aqueous solution , ligand (biochemistry) , medicinal chemistry , inorganic chemistry , crystal structure , alkyl , organic chemistry , biochemistry , receptor
Solvent shell coupled electron transfer (ET) reaction, principally between Co III (en) 2 Br(L) 2+ and Fe(CN) 6 4−complexes (L = RC 6 H 4 NH 2 ; R = m ‐OCH 3, p ‐F, H, m ‐CH 3 , p ‐CH 3, p ‐OC 2 H 5 , and p ‐OCH 3 ) in H 2 O/EtOH binary mixed solvents has been investigated. The cobalt(III)‐aryl amine complexes have been structurally refined by powder X‐ray diffraction (PXRD) data as monoclinic unit cell with a distorted geometry. Cyclic voltammograms of the complexes exhibit Co III /Co II and Co II /Co I reduction peaks with an indication of participation of electron accepting/donating abilities of RC 6 H 4 NH 2 in the reduction. The ΔEp (50–580 mV) and Ic/ ν ½ (0.12–2.83) values differ for the complexes. ET between Co III (en) 2 Br(L) 2+ and Fe(CN) 6 4−is due to ion pair, {Co III (en) 2 Br(L) 2+ ; Fe(CN) 6 4− }, formation leading to product via (i) solvent caged ({Co III …Fe II }, restricted mobility due to RC 6 H 4 NH 2 ) and (ii) solvent controlled (electron accepting/donating substituent in aryl ligand concertedly alters the equilibrium: reactants ↔ ion pair) mechanisms. Reduction was followed in 0–30% v/v ( x 2 : x EtOH = 0, 0.0159–0.1162) aqueous ethanol solutions at 286, 293, and 300 K. Reaction follows second‐order condition and there is a gradation in rate when x 2 = 0–0.1162 representing co‐solvent influence. This tendency is understood in the attainment of equilibrium and the formed compact ion pair. In order to estimate the solvent influence, the rate data were subjected to linear and multiple regression analyses using Y s = Y 0 + a 1 X 1 + a 2 X 2 + a 3 X 3 …a n X n correlation relationship. Copyright © 2010 John Wiley & Sons, Ltd.