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New Cobalt(II) Field‐Induced Single‐Molecule Magnet and the First Example of a Cobalt(III) Complex with Tridentate Binding of a Deprotonated 4‐Amino‐3,5‐bis(pyridin‐2‐yl)‐1,2,4‐Triazole Ligand
Author(s) -
Váhovská Lucia,
Bukrynov Oleksandr,
Potočňák Ivan,
Čižmár Erik,
Kliuikov Andrii,
Vitushkina Svitlana,
Dušek Michal,
Herchel Radovan
Publication year - 2019
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201801225
Subject(s) - chemistry , crystallography , molecule , deprotonation , single molecule magnet , supramolecular chemistry , crystal structure , magnetization , magnetic field , ion , physics , organic chemistry , quantum mechanics
From Co(NO 3 ) 2 · 6H 2 O ‐ NaN 3 ‐ abpt reaction system, a mononuclear complex [Co(abpt) 2 (N 3 ) 2 ] (abpt = 4‐amino‐3,5‐bis(pyridin‐2‐yl)‐1,2,4‐triazole) ( 1 ) and a dinuclear complex [Co 2 (abpt)(µ‐abpt‐H) 2 (N 3 ) 4 ] · 1.12H 2 O ( 2 ) were obtained. The presence of neutral abpt, as well as azido ligands was proved by IR spectroscopy. X‐ray crystallography shows that 1 is a molecular Co II complex with two azido ligands coordinated in trans ‐positions, while 2 is a dinuclear Co III complex bridged by two abpt‐H ligands. π–π stacking interactions between pyridyl rings of abpt and N‐H ··· N and C‐H ··· N hydrogen bonds in 1 and 2 stabilize their structures by creating a 3D supramolecular network. The analysis of the magnetic properties of 1 revealed negative zero‐field splitting parameter D = –24.1 cm –1 supported also by CASSCF/NEVPT2 and CASSCF/CASPT2 theoretical calculations. The X‐band electron paramagnetic resonance also gives an evidence for a strong rhombic character of the anisotropy. The investigation of the ac susceptibility measurements identified 1 as a field‐induced single‐molecule magnet, in which direct, Raman and Orbach relaxation processes are present.