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]