Dinuclear Complexes with Dithiolate‐bridged Square‐pyramidal and Octahedral Nickel(II) Ions – Syntheses, Characterization, and Crystal Structures

The ability of the dinuclear nickel(II) complex [Ni II 2 L(L′)] + , where L 2− represents a macrocyclic N 6 S 2 ligand, to coordinate monodentate coligands has been examined. Three complexes with L′ = CH 3 CN, CH 2 =CHCN, and (BH 3 CN) − have been synthesized: [Ni II 2 (L)(NCMe)][BPh 4 ] 2 ( 3 ), [Ni II 2 (L)(NCCH=CH 2 )][BPh 4 ] 2 ( 4 ), and [Ni II 2 (L)(NCBH 3 )][ClO 4 ] ( 5 ). All complexes were characterized by elemental analysis, IR and UV/Vis spectroscopy, and X‐ray crystallography. The complexes were found to be isostructural. Each coligand is bonded in a monodentate fashion to generate a central N 3 Ni(SR) 2 NiN 4 core structure, with the dithiolate‐bridged Ni II ions in square‐pyramidal N 3 S 2 and distorted‐octahedral N 4 S 2 coordination environments, respectively. The charged (BH 3 CN) − group interacts more strongly with the [Ni 2 L] 2+ fragment than the neutral nitrile ligands as reflected by the Ni–N(nitrile) distances which are significantly longer in 3 and 4 than in 5 . An analysis of the temperature‐dependent magnetic susceptibility data for 3 reveals the presence of weak ferromagnetic exchange interactions between the Ni II ions with a value for the magnetic exchange coupling constant J of 39 cm −1 ( H = −2 J S 1 S 2 ).