McConnell I mechanism promotes ferromagnetic interactions between π-stacked Ni(II)-thiazyl complexes

The coordination complex of Ni(hfac)(2) (hfac = 1,1,1,5,5,5-hexa-fluoroacetylacetonato) and the 4-(benzoxazol-2'-yl)-1,2,3,5-dithiadiazolyl (boaDTDA) neutral radical pi-stacks in a one-dimensional staircase'' arrangement. This particular packing aligns regions of alpha and beta spin densities on neighbouring Ni-II(hfac)(2)(boaDTDA) molecules. This complex exemplifies a McConnell I type mechanism, giving rise to intermolecular ferromagnetic exchange observed for the first time between metal-thiazyl complexes.