Rapid Electron Transfer Self-Exchange in Conformationally Dynamic Copper Coordination Complexes

07 June 2023, Version 1
This content is a preprint and has not undergone peer review at the time of posting.

Abstract

We report the electron transfer (ET) self-exchange rate constants (k11) for a pair of CuII/I complexes utilizing dpaR (dpa = dipicolylaniline, R = OMe, SMe) ligands assessed by NMR line-broadening experiments. These ligands afford copper complexes that are conformationally dynamic in one oxidation state. With R = OMe, the CuI complex is dynamic, while with R= SMe, the CuII complex is dynamic. Both complexes exhibit unexpectedly large k11 of 2.48(6) x 105 and 2.21(9) × 106 M‒1 s‒1 for [CuCl(dpaOMe)]+/0 and [CuCl(dpaSMe)]+/0, respectively. Among the fastest reported for molecular copper coordination complexes to date, that of [CuCl(dpaSMe)]+/0 exceeds all others by an order of magnitude and compares only to those observed in type 1 blue copper proteins. The dynamicity of these complexes establish pre-steady-state con-formational equilibria that minimize the inner sphere reorganization energies to 0.71 and 0.62 eV for R = OMe and SMe, respectively. In contrast to the emphasis on rigidity in the formulation of entatic states applied to blue copper proteins, the success of these two systems highlight the relevance of conformational dynamicity in mediating rapid ET.

Keywords

bioinorganic chemistry
electron transfer
copper

Supplementary materials

Title
Description
Actions
Title
Supplementary Information
Description
Materials and methods, XRD structure and refinement for CuCl(dpaOMe) (CCDC: 2267971), scan rate dependence, raw NMR line-broadening data, EPR spectra, and DFT-optimized coordinates.
Actions

Comments

Comments are not moderated before they are posted, but they can be removed by the site moderators if they are found to be in contravention of our Commenting Policy [opens in a new tab] - please read this policy before you post. Comments should be used for scholarly discussion of the content in question. You can find more information about how to use the commenting feature here [opens in a new tab] .
This site is protected by reCAPTCHA and the Google Privacy Policy [opens in a new tab] and Terms of Service [opens in a new tab] apply.