title: Remarkably different structures of two metalloporphyrins containing M2O34+ units.
mesh_terms: D055598:Chemical Phenomena; D002621:Chemistry; D003461:Crystallography; D008665:Metalloporphyrins; D008982:Molybdenum; D009556:Niobium; D010100:Oxygen
chemical_list: D008665:Metalloporphyrins; D009556:Niobium; D008982:Molybdenum; D010100:Oxygen