From Paramagnetic to Single‐Molecule Magnet Behaviour in Heterobimetallic Compounds Containing the Tetrakis(thiocyanato‐κN)cobaltate(II) Anion

Abstract

Four heterobimetallic compounds of formula [Ni-(Me 6 trans[14]dieneN 4 )][Co(NCS) 4 ] (1 and 2), [Ni(Me 6 trans[14]di-eneN 4 )] 2 [Co(NCS) 4 ](ClO 4 ) 2 ·H 2 O (3) and [Ni(Me 6 trans[14]-dieneN 4 )] 2 [Co(NCS) 4 ](PF 6 ) 2 (4) (Me 6 trans[14]dieneN 4 = 5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-4,11diene) have been synthesised and structurally characterised. Their structures are formed of square-planar [Ni-(Me 6 trans[14]dieneN 4 )] 2+ cations and tetrahedral [Co(NCS) 4 ] 2-anions. The variable-temperature magnetic properties of 2-4 mainly obey the zero-field splitting effects (D) of the 4 A 2 ground-state term of the pseudo-tetrahedral [Co(NCS) 4 ] 2anionic complex (2D is the energy gap between the |±1/2> and [a]

Effect of Coordination Geometry on Magnetic Properties in a Series of Cobalt(II) Complexes and Structural Transformation in Mother Liquor

“…Thus, in order to minimize the probability of the quantum relaxation pathway in zero dc field and to estimate the energy barrier accurately, the ac susceptibility was measured under different dc fields. It is worth mentioning that no slow relaxation of magnetization was detected in the case of complex 1 from ac susceptibility measurements even by using a 6000 Oe dc magnetic field (Figure S21), although slow relaxation of magnetization has recently been reported in [Co­(N3) 2 ]­[Co­(NCS) 4 ] (N3 = tridentate N-donor ligand) types of complexes as well as in the [Co­(NCS) 4 ] 2– unit with different metal cation complexes. − …”