The tunnel states of square-planar bielectron transfer dn-dn-dn+l-d n+l (n = 0-4) clusters are considered. The nature of the ground spin state is revealed in the limiting case of a strong double exchange. It is shown that the magnetic propem'es of these systems radically differ from those of clusters with one migrating electron (hole) and tetrameric tetrahedral bielectron transfer clusters.