Avril 2021.

Publication de l'équipe CIMI du laboratoire Moltech-Anjou dans le journal Molecules.

Mono- and Binuclear Copper(II) and Nickel(II) Complexes with the 3,6-Bis(picolylamino)-1,2,4,5-Tetrazine Ligand.

ABSTRACT: Four new compounds of formulas [Cu(hfac)2(L)] (1), [Ni(hfac)2(L)] (2), [{Cu(hfac)2}2(-
L)]2CH3OH (3) and [{Ni(hfac)2}2(-L)]2CH3CN (4) [Hhfac = hexafluoroacetylacetone and L = 3,6-bis(picolylamino)-1,2,4,5-tetrazine] have been prepared and their structures determined by Xray diffraction on single crystals. Compounds 1 and 2 are isostructural mononuclear complexes where the metal ions [copper(II) (1) and nickel(II) (2)] are six-coordinated in distorted octahedral MN2O4 surroundings which are built by two bidentate hfac ligands plus another bidentate L molecule. This last ligand coordinates to the metal ions through the nitrogen atoms of the picolylamine fragment.
Compounds 3 and 4 are centrosymmetric homodinuclear compounds where two bidentate hfac units are the bidentate capping ligands at each metal center and a bis-bidentate L molecule acts as a bridge. The values of the intramolecular metalmetal separation are 7.97 (3) and 7.82 Å (4).
Static (dc) magnetic susceptibility measurements were carried out for polycrystalline samples 1–4 in the temperature range 1.9–300 K. Curie law behaviors were observed for 1 and 2, the downturn of MT in the low temperature region for 2 being due to the zero-field splitting of the nickel(II) ion. Very weak [J = -0.247(2) cm-1] and relatively weak intramolecular antiferromagnetic interactions [J = -4.86(2) cm-1] occurred in 3 and 4, respectively (the spin Hamiltonian being defined as H = -JS1S2). Simple symmetry considerations about the overlap between the magnetic orbitals across the extended bis-bidentate L bridge in 3 and 4 account for their magnetic properties.


DOI: https://doi.org/10.3390/molecules26082122