Magneto-Structural Correlation of Five-Coordinate Trigonal Bipyramidal High Spin Cobalt(II) Complexes.

Autor: Zhang P; Chinese Academy of Sciences Dalian Institute of Chemical Physics, State Key Laboratory of Catalysis, CHINA., Tian YC; National Taiwan Normal University, Department of Chemistry, TAIWAN., Wang Z; Huazhong University of Science and Technology, Wuhan National High Magnetic Field Center & School of Physics, CHINA., Lee WZ; National Taiwan Normal University, Department of Chemistry, TAIWAN., Ye S; Dalian Institute of Chemical Physics, Chinese Academy of Sciences, State Key Laboratary of Catalysis, 457 Zhongshan Road, 116023, Dalian, CHINA.
Jazyk: angličtina
Zdroj: Chemistry (Weinheim an der Bergstrasse, Germany) [Chemistry] 2024 Mar 04, pp. e202400336. Date of Electronic Publication: 2024 Mar 04.
DOI: 10.1002/chem.202400336
Abstrakt: Here, we combined magnetometry, multi-frequency electronic paramagnetic resonance, and wave function based ab initio calculations to investigate magnetic properties of two high spin Co(II) complexes Co(BDPRP) (BDPRP = 2,6-bis((2-(S)-di(4-R)phenylhydroxylmethyl-1-pyrrolidinyl)methyl)pyridine) complexes (R = H for 8; R = tBu for 9). Complexes 8 and 9 featuring effective D3h symmetry were found to possess D = 24.0 and 32.0 cm-1, respectively, in their S = 3/2 ground states of . Ligand field analyses revealed that the low-lying d-d excited states make either positive or vanishing contributions to D. Hence, total positive D values were measured for 8 and 9, as well as related D3h high spin Co(II) complexes. In contrast, negative D values are usually observed for C3v congeners. In-depth analyses suggested that lowering symmetry from D3h to C3v induces orbital mixing between  and  and admixes excited state  into the ground state. Both factors turn the total D value progressively negative with the increasing distance (δ) of the Co(II) out of the equatorial plane. Therefore, δ determines the sign and magnitude of final D values of five-coordinate trigonal bipyramidal S = 3/2 Co(II) complexes as measured for a series of such species with varying δ.
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Databáze: MEDLINE
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