1-Carboxymethyl-2-imino-3-phosphonoimidazolidine 1-Carboxymethyl-2-iminophosphoimidazolidine 1-Imidazolidineacetic acid, 2-imino-3-phosphono- 61839-19-8 Cyclocreatine phosphate N-Phosphorylcyclocreatine Phosphocyclocreatine