Potential-Dependent Redox Speciation in Substituted MnIII and CrIII Phthalocyanines
- 1Department of Chemistry
- 2University of Tennessee
- 3Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia, Canada, V5A 1S6
Abstract
We performed a comprehensive electrochemical and spectroelectrochemical study of three transition metal phthalocyanine (Pc) complexes, Pc n-OBu (2−)Mn III Cl, Pc tBu (2−)Mn III Cl and Pc tBu (2−)Cr III Cl (Pc tBu is the dianion of 2,9(10),16(17),23(24)-tetra- tert -butyl-phthalocyanine and Pc n-OBu is the dianion of 1,4,8,11,15,18,22,25-octa-n-butoxy-phthalocyanine), that are relevant for a variety of bond-breaking and forming reactions. Syntheses were optimized for previously reported tert -butylated species. Solvent-dependent voltammetry, spectroelectrochemistry, and for the first time for Mn III and Cr III Pc derivatives, spectroelectrochemical magnetic circular dichroism (MCD), were used to assess ligand- versus metal-centered redox events, electrochemical and chemical reversibilities of electron transfer, and effects of axial ligand coordination in dichloromethane or chloroform (DCM or CHCl 3 ) versus N,N -dimethylformamide (DMF). Comparisons are made to previously reported voltammetry and spectra of both Pc(2−)Mn II and chemically prepared oxidation states of Pc(2−)Cr II . We observe differences in localization of reduction events in P c n-OBu (2−)Mn III Cl versus Pc tBu (2−)Mn III Cl, with a more electron-rich ring promoting formation of MnI over Pc-centered reduction. We observe unique reduction behavior in Pc tBu (2−)Cr III Cl that points towards a mixture of ligand- and metal-centered character. To the best of our knowledge, these studies represent the first complete solvent-dependent spectroelectrochemical characterization of both Mn III and Cr III phthalocyanine derivatives across up to six different oxidation states.
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BibTeX
@misc{tuggle2026potentialdependent,
title = {{Potential-Dependent Redox Speciation in Substituted MnIII and CrIII Phthalocyanines}},
author = {Kelsie J. Tuggle and Haleigh M. Grace and Breanna E. Muldowney and Ryan S. Arnold and Daniel B. Leznoff and Viktor N. Nemykin and Brendon J. McNicholas},
howpublished = {ChemRxiv},
year = {2026},
month = sep,
doi = {10.26434/chemrxiv.15008429/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008429/v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - Potential-Dependent Redox Speciation in Substituted MnIII and CrIII Phthalocyanines
AU - Kelsie J. Tuggle
AU - Haleigh M. Grace
AU - Breanna E. Muldowney
AU - Ryan S. Arnold
AU - Daniel B. Leznoff
AU - Viktor N. Nemykin
AU - Brendon J. McNicholas
PY - 2026
DA - 2026/09/07
PB - ChemRxiv
DO - 10.26434/chemrxiv.15008429/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008429/v1
AB - We performed a comprehensive electrochemical and spectroelectrochemical study of three transition metal phthalocyanine (Pc) complexes, Pc n-OBu (2−)Mn III Cl, Pc tBu (2−)Mn III Cl and Pc tBu (2−)Cr III Cl (Pc tBu is the dianion of 2,9(10),16(17),23(24)-tetra- tert -butyl-phthalocyanine and Pc n-OBu is the dianion of 1,4,8,11,15,18,22,25-octa-n-butoxy-phthalocyanine), that are relevant for a variety of bond-breaking and forming reactions. Syntheses were optimized for previously reported tert -butylated species. Solvent-dependent voltammetry, spectroelectrochemistry, and for the first time for Mn III and Cr III Pc derivatives, spectroelectrochemical magnetic circular dichroism (MCD), were used to assess ligand- versus metal-centered redox events, electrochemical and chemical reversibilities of electron transfer, and effects of axial ligand coordination in dichloromethane or chloroform (DCM or CHCl 3 ) versus N,N -dimethylformamide (DMF). Comparisons are made to previously reported voltammetry and spectra of both Pc(2−)Mn II and chemically prepared oxidation states of Pc(2−)Cr II . We observe differences in localization of reduction events in P c n-OBu (2−)Mn III Cl versus Pc tBu (2−)Mn III Cl, with a more electron-rich ring promoting formation of MnI over Pc-centered reduction. We observe unique reduction behavior in Pc tBu (2−)Cr III Cl that points towards a mixture of ligand- and metal-centered character. To the best of our knowledge, these studies represent the first complete solvent-dependent spectroelectrochemical characterization of both Mn III and Cr III phthalocyanine derivatives across up to six different oxidation states.
ER -