TY - JOUR

T1 - Ab initio and density functional theory study of the electronic structure of rhenium complexes with noninnocent dioxolene ligands

T2 - Localized vs delocalized valence states

AU - Dmitriev, Alexey A.

AU - Gritsan, Nina P.

N1 - Publisher Copyright: © 2019 Wiley Periodicals, Inc.

PY - 2019/12/5

Y1 - 2019/12/5

N2 - The dioxolene type ligands (Diox) derived from ortho-quinones are the most widely studied redox noninnocent ligands existing in the dianionic (Cat), anion radical (SQ) or neutral (Q) forms although a highly delocalized electronic structure is also possible. For [ReO(Diox)2PPh3]− (2) and [ReCl3(Diox)PPh3] (3) complexes, the ReV-Cat2 and ReIV-SQ localized valence states were proposed on the basis of their XRD structures. To understand in detail the electronic structure of these complexes, we performed a series of the all-electron calculations at the DKH2-CASSCF/CASPT2 and DKH2-CASSCF/NEVPT2 levels taking into account scalar relativistic and spin-orbit effects. All calculations predicted that 2 has a singlet ground state with a predominant contribution of a single electronic configuration with doubly occupied molecular orbitals being pure o-quinone LUMOs of both Diox ligands that corresponds to the ReV-Cat2 valence state. Complex 3 has a triplet ground state with four electronic configurations contributing mainly into its wavefunction and differing by the occupation of bonding and antibonding combinations of the o-quinone LUMO and rhenium d-AO with nearly equal contributions. This leads to the empirical “metrical oxidation state” of dioxolene ligand being −1 that is usually referred to the ReIV-SQ oxidation state. However, in fact, the negative charge on the Diox ligand is mainly provided by a pair of electrons on the bonding MO. The standard DFT calculations entirely fail to correctly predict the ground state multiplicity for 3.

AB - The dioxolene type ligands (Diox) derived from ortho-quinones are the most widely studied redox noninnocent ligands existing in the dianionic (Cat), anion radical (SQ) or neutral (Q) forms although a highly delocalized electronic structure is also possible. For [ReO(Diox)2PPh3]− (2) and [ReCl3(Diox)PPh3] (3) complexes, the ReV-Cat2 and ReIV-SQ localized valence states were proposed on the basis of their XRD structures. To understand in detail the electronic structure of these complexes, we performed a series of the all-electron calculations at the DKH2-CASSCF/CASPT2 and DKH2-CASSCF/NEVPT2 levels taking into account scalar relativistic and spin-orbit effects. All calculations predicted that 2 has a singlet ground state with a predominant contribution of a single electronic configuration with doubly occupied molecular orbitals being pure o-quinone LUMOs of both Diox ligands that corresponds to the ReV-Cat2 valence state. Complex 3 has a triplet ground state with four electronic configurations contributing mainly into its wavefunction and differing by the occupation of bonding and antibonding combinations of the o-quinone LUMO and rhenium d-AO with nearly equal contributions. This leads to the empirical “metrical oxidation state” of dioxolene ligand being −1 that is usually referred to the ReIV-SQ oxidation state. However, in fact, the negative charge on the Diox ligand is mainly provided by a pair of electrons on the bonding MO. The standard DFT calculations entirely fail to correctly predict the ground state multiplicity for 3.

KW - DFT and CASSCF

KW - dioxolene ligands

KW - electronic structure

KW - metrical oxidation state

KW - rhenium complexes

KW - CATECHOLATE

KW - TRANSITION-METAL-COMPLEXES

KW - APPROXIMATION

KW - SEMIQUINONE

KW - CRYSTAL-STRUCTURE

KW - CORRELATION-ENERGY

KW - IMPLEMENTATION

KW - 2ND-ORDER PERTURBATION-THEORY

KW - BASIS-SETS

KW - TAUTOMERISM

UR - http://www.scopus.com/inward/record.url?scp=85069668127&partnerID=8YFLogxK

U2 - 10.1002/qua.26018

DO - 10.1002/qua.26018

M3 - Article

AN - SCOPUS:85069668127

VL - 119

JO - International Journal of Quantum Chemistry

JF - International Journal of Quantum Chemistry

SN - 0020-7608

IS - 23

M1 - 26018

ER -