Spin crossover mediated by hydrogen bonds in iodine-substituted manganese complexes

Qin, Chunyan; Zhou, Hua-Wei; Zhao, Sheng-Ze; Li, Yonghua; Wang, Shi

doi:10.1016/j.molstruc.2022.134513

Cited by 1 publication

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“… The spin crossover property of this class of complexes was later characterized by Morgan et al in 2006 . The roles of the substituents, counterions, and solvent in spin crossover and other physical phenomena have also been investigated. − …”

Section: Introductionmentioning

confidence: 99%

Importance of Dispersion in the Molecular Geometries of Mn(III) Spin-Crossover Complexes

2023

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The computational investigation of the molecular geometries of a pair of manganese(III) spin-crossover complexes is reported. For the geometry of the quintet high-spin state, density functionals significantly overestimate Mn–Namine bond distances, although the geometry for the triplet intermediate-spin state is well described. Comparisons with several wave function-based methods demonstrate that this error is due to the limited ability of commonly used density functionals to recover dispersion beyond a certain extent. Among the methods employed for geometry optimization, restricted open-shell Møller–Plesset perturbation theory (MP2) appropriately describes the high-spin geometry but results in a slightly shorter Mn–O distance in both spin states. On the other hand, extended multistate complete active space second-order perturbation theory (XMS-CASPT2) provides a good description of the geometry for the intermediate-spin state but also sufficiently recovers dispersion, performing well for the high-spin state. Despite the fact that the electronic structure of both spin states is dominated by one-electron configuration, XMS-CASPT2 offers a balanced approach, leading to molecular geometries with much better agreement with experiment than MP2 and DFT. A scan along the Mn–Namine bond demonstrates that for these complexes coupled cluster methods (i.e., DLPNO-CCSD(T)) also yield bond distances in agreement with experiment while multiconfiguration pair density functional theory (MC-PDFT) is unable to recover dispersion well enough, analogous to single-reference DFT.

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