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Redox Characteristics and Anion Association Behaviour of Stereoisomeric Forms of Mono‐ and Oligonuclear Metal Complexes Using High Pressure Electrochemistry
Author(s) -
Yeomans Brett D.,
Kelso Laurence S.,
Tregloan Peter A.,
Keene F. Richard
Publication year - 2001
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/1099-0682(20011)2001:1<239::aid-ejic239>3.0.co;2-2
Subject(s) - chemistry , redox , electrochemistry , metal , ion , solvent , inorganic chemistry , electrostriction , crystallography , metal ions in aqueous solution , organic chemistry , electrode , materials science , piezoelectricity , composite material
The effect of the presence of the anions PF 6 − , BF 4 − , ClO 4 − , and tosylate − on the potentials of the Ru III/II redox processes in a series of mono‐, di‐, and trinuclear complexes involving polypyridyl ligands are reported. The anions gives rise to a cathodic shift in the respective redox potentials in the sequence PF 6 − < BF 4 − ≈ ClO 4 − < tos − , with the magnitude of the shifts being largest for the tri‐nuclear and smallest for the mononuclear species. In one dinuclear complex, a variation of anion was also observed to affect the difference in potentials between the [6+/5+] and [5+/4+] couples. These effects are consistent with known specific association of the anions with metal complexes of this type. In the presence of PF 6 − , high‐pressure electrochemical studies revealed the molar volume changes for successive redox couples in di‐ and tri‐nuclear complexes were almost invariant (Δ V complex = 24 ± 2 cm 3 mol −1 ) and consistent with the value for mononuclear species. This constancy is interpreted in terms of isolated Ru III/II processes in all complexes and implies that the electrostrictive effects on solvent are limited to a very short range.