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Mononuclear and One‐Dimensional Cobalt(II) Complexes with the 3,6‐Bis(picolylamino)‐1,2,4,5‐tetrazine Ligand
Author(s) -
Stetsiuk Oleh,
ElGhayoury Abdelkrim,
Lloret Francesc,
Julve Miguel,
Avarvari Narcis
Publication year - 2018
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.201701224
Subject(s) - chemistry , tetrazine , crystallography , ligand (biochemistry) , cobalt , pyridine , denticity , magnetic susceptibility , crystal structure , stereochemistry , ion , inorganic chemistry , medicinal chemistry , organic chemistry , biochemistry , receptor
We describe herein the synthesis and structural characterization of a tetrazine‐based bis(picolylamine) ligand, namely, N 3 , N 6 ‐bis(pyridin‐2‐ylmethyl)‐1,2,4,5‐tetrazine‐3,6‐diamine (L, 1 ), which was prepared by the direct reaction between 2 equiv. of picolylamine and 3,6‐dichloro‐1,2,4,5‐tetrazine. Its reaction with cobalt(II) hexafluoroacetylacetonate hydrate afforded the mononuclear complex [Co(hfac) 2 L] · CH 3 CN ( 2 , Hhfac = hexafluoroacetylacetone) and the chain compound {[Co(hfac) 2 (µ‐L)][Co(hfac) 2 (CH 3 OH) 2 ]} n ( 3 ). The crystal structures of 1 – 3 were determined by X‐ray structure analysis. The metal centre in 2 is trischelated by two hfac ligands and one picolylamine unit. The two crystallographically independent cobalt(II) ions in 3 (Co1 and Co2) are six‐coordinate. Two bidentate hfac groups in equatorial positions and two trans ‐positioned pyridine nitrogen atoms build the coordination polyhedron around Co1 to form a neutral zigzag chain compound, which cocrystallizes with the mononuclear species trans ‐[Co 2 (hfac) 2 (CH 3 OH) 2 ]. The magnetic properties of 2 and 3 were investigated in the temperature range 1.9–300 K. The decrease of the χ M T values of 2 and 3 upon cooling is mainly due to the depopulation of the higher energy Kramers doublets of the magnetically isolated six‐coordinate cobalt(II) ions. Alternating‐current (ac) magnetic susceptibility measurements of 2 and 3 revealed the occurrence of frequency‐dependent out‐of‐phase signals under applied direct‐current (dc) fields at very low temperatures, and this result is indicative of single‐ion magnet (SIM) behaviour.