CASSCF-based explicit ligand field models clarify the ground state electronic structures of transition metal phthalocyanines (MPc; M = Mn, Fe, Co, Ni, Cu, Zn)

Type of content
Journal Article
Thesis discipline
Degree name
Publisher
Canadian Science Publishing
Journal Title
Journal ISSN
Volume Title
Language
en
Date
2016
Authors
Wallace AJ
Crittenden, Deborah
Williamson, Bryce
Abstract

© 2016 Published by NRC Research Press. Multireference electronic structure methods are used to assign ground state electronic configurations for a series of metallophthalocyanines. Ligand orbital occupancies remain constant across the period and are consistent with a formal 2-charge on the ligand. The d electron configurations of some metallophthalocyanines are straightforward and can be unambiguously assigned, (dxy)2(dxz,dyz)2,2(dz2)2(dx2-y2)n, with n = 2, 1, 0, respectively, for ZnPc, CuPc, and NiPc. Controversies over ground state electronic structure assignments for other metallophthalocyanines arise due to multiple complicating factors: accidental near-degeneracies, environmental effects, and different ligand field models used in interpreting experimental spectra. We demonstrate that explicit ligand field models provide more reliable and consistent interpretations of experimental data than implicit, parameterized alternatives. On this basis, we assign gas-phase electronic ground states for MnPc, (dxy)2(dxz,dyz)1,1(dz2)1and CoPc, (dxy)2(dxz,dyz)2,2(dz2)1, and show that the ground state of FePc cannot be resolved to a single state, with two near-degenerate states that are likely spin-orbit coupled: (dxy)2(dxz,dyz)1,1(dz2)2and (dxy)2(dxz,dyz)2,1(dz2)1. Remaining differences between computational predictions and experimental observations are small and may be ascribed primarily to environmental effects but are also partly due to incomplete modelling of electron correlation.

Description
Citation
Wallace AJ, Williamson BE, Crittenden DL (2016). CASSCF-based explicit ligand field models clarify the ground state electronic structures of transition metal phthalocyanines (MPc; M = Mn, Fe, Co, Ni, Cu, Zn). Canadian Journal of Chemistry. 94(12). 1163-1168.
Keywords
ligand field theory, CASSCF, MRMP2, phthalocyanine, multireference
Ngā upoko tukutuku/Māori subject headings
ANZSRC fields of research
03 Chemical Sciences
Fields of Research::34 - Chemical sciences::3405 - Organic chemistry::340505 - Physical organic chemistry
Fields of Research::34 - Chemical sciences::3402 - Inorganic chemistry::340209 - Organometallic chemistry
Fields of Research::34 - Chemical sciences::3407 - Theoretical and computational chemistry::340701 - Computational chemistry
Fields of Research::34 - Chemical sciences::3406 - Physical chemistry::340604 - Electrochemistry
Rights
All rights reserved unless otherwise stated