2,2′ : 6′,2″ : 6″,2‴-Quaterpyridine (qtpy): a versatile ligand in metallosupramolecular chemistry; crystal and molecular structures of [Ni(qtpy)(OH2)2][BF4]2, [Pd(qtpy)][PF6]2, [Cu2(qtpy)2][Pf6]2and [Ag2(qtpy)2][BF4]2 | Publicación