A multifaceted study has been conducted on the electron-transfer reactions of the copper(II/I) complexes formed with 2,3-cis- and 2,3-trans-cyclohexanediyl-1,4,8,11-tetrathiacyclotetradecane (designated as cis- and tmns-cyhx-[14]aneS(4)). Each system has been studied by (i) H-1-NMR line broadening in D2O to determine the electron self-exchange rate constants at zero driving force, (ii) rapid-scan cyclic voltammetry in 80% methanol-20% water (w/w) to determine the rate constants for conformational changes and heterogeneous electron transfer, and (iii) stopped-flow spectrophotometry using a total. of eight oxidizing and reducing counterreagents to determine the cross-reaction electron-transfer rate constants from which self-exchange rate constants can be calculated for various driving forces. The crystal structures of both Cu(II)L complexes and of Cu-I(trans-cyhx-[14]aneS(4)) have also been determined. From the NMR measurements, the electron self-exchange rate constants have been evaluated [at 25 degrees C, mu = 0.10 M (NO3-)] as k(11(ex)) = (5.0 +/- 0.5) x 10(4) and less than or equal to 10(3) M(-1) s(-1) for Cd-II/I(cis-) and Cu-II/I(trans-cyhx-[14]aneS(4)), respectively. Application of the Marcus relationship to the numerous cross-reaction rate constants yields variable behavior which is consistent with a dual-pathway mechanism for which the following self-exchange rate constants have been resolved [25 degrees C, mu = 0.10 M (ClO4-)] : for Cu-II/I(cis-cyhx-[14]aneS(4)), k(11(A)) = 5 x 10(4), k(11(B)) less than or equal to 10 M(-1) s(-1); for Cu-II/I(trans-cyhx-[14]aneS(4)), k(11(A)) = 2 x 10(3), k(11(B)) less than or equal to 10 M(-1) s(-1).