Dioxatriazamacrocycle-N,N ',N ''-Triacetic Acids: Synthesis, Protonation Constants, and Metal-Complex Studies. Crystal Structure of Hydrogen [1,4-Dioxa-7,10,13-Triazacyclopentadecane-7,10,13-Triacetato(4)-Kappa N-7,Kappa N-11,Kappa N-13,Kappa O-7]Copper(1-) Hydrate (2 : 1) ([Cu(Hl1)]Center Dot 0.5 H2O)