A trinuclear nickel(ii) Schiff base complex with phenoxido- and acetato-bridges: combined experimental and theoretical magneto-structural correlation. Issue 6 (27th January 2021) - Thakurta, Santarupa
Abstract : A new Ni(ii ) trimer with single-phenoxido and acetato bridges has been prepared and structurally characterized. Magnetic measurements and theoretical calculations allow to establish a magneto-structural correlation for this kind of bridges. Abstract : We describe the synthesis and characterization of a new trinuclear Ni(ii ) Schiff base complex of formula [Ni3 (L)2 (NCS)2 (OAc)2 (CH3 OH)2 ] (1 ) where HL is the 1 : 1 condensation product of 2-picolylamine and o -vanillin. The crystal structure of complex 1 shows that the two terminal Ni(ii ) ions are connected to the central one through a phenoxido- and a syn–syn acetato bridge, giving rise to a very bent configuration in the Ni3 -core. Magnetic susceptibility measurements show the presence of a weak antiferromagnetic coupling with J = −3.22(2) cm −1 . We also report a magneto-structural correlation, performed with all the magnetically characterized Ni(ii ) trimers with similar bridges, showing a linear dependence between the J value and the dihedral angle ( θ ) between the planes containing the Ni–O–Ni and the carboxylate bridges. The super-exchange interaction is investigated by extensive density functional calculations within the broken symmetry approximation which show good agreement with the experimental data. The analysis of the spin density distribution and the shape of the magnetically active single occupied molecular orbitals (SOMO) provide a mechanism of exchange coupling through the bridging groups.