Open AccessRoom-Temperature Spin Crossover in a Solution of Iron(II) Complexes with N,N′-Disubstituted Bis(pyrazol-3-yl)pyridines
Author(s) -
Dmitry Yu. Aleshin,
Igor A. Nikovskiy,
Valentin V. Novikov,
Alexander V. Polezhaev,
Elizaveta K. Melnikova,
Yulia V. Nelyubina
Publication year - 2021
Publication title -
acs omega
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.779
H-Index - 40
ISSN - 2470-1343
DOI - 10.1021/acsomega.1c05463
Subject(s) - spin crossover , chemistry , substituent , pyridine , ligand (biochemistry) , solvent , polar effect , polar , spin states , hydrogen bond , crystallography , medicinal chemistry , stereochemistry , photochemistry , molecule , inorganic chemistry , organic chemistry , biochemistry , physics , receptor , astronomy
Here, we report a combined study of the effects of two chemical modifications to an N , N '-disubstituted bis(pyrazol-3-yl)pyridine (3-bpp) and of different solvents on the spin-crossover (SCO) behavior in otherwise high-spin iron(II) complexes by solution NMR spectroscopy. The observed stabilization of the low-spin state by electron-withdrawing substituents in the two positions of the ligand that induce opposite electronic effects in SCO-active iron(II) complexes of isomeric bis(pyrazol-1-yl)pyridines (1-bpp) was previously hidden by NH functionalities in 3-bpp precluding the molecular design of SCO compounds with this family of ligands. With the recent SCO-assisting substituent design, the uncovered trends converged toward the first iron(II) complex of N , N '-disubstituted 3-bpp to undergo an almost complete SCO centered at room temperature in a less polar solvent of a high hydrogen-bond acceptor ability.