Structures and conformations of protonated O2N2- and O2N3-macrocyclic ligand salts

Abstract

Single crystal X-ray structure determinations are described for salts of 5,6,14,15-dibenzo-1,4-dioxa-8,12-diazacyclopentadeca-5,14-diene (L1) (mono-protonated, as its image (‘tfs’) salt, and diprotonated, as its nitrate salt) and 5,6,17,18-dibenzo-1,4-dioxa-8,11,15-triazacyclooctadeca-5,17-diene (L2) (diprotonated, as its tfs salt), defining their protonic hydrogen atom distributions and conformations. In (L1H)(tfs), an NH group is protonated, the associated hydrogen atoms interacting one within the cation to the other NH group, the other with a tfs oxygen atom. In (L1H2)(NO3)2 (two phases), both NH groups are protonated; in each case, although one image group is oriented so that one of its hydrogen atoms is directed within the ring to the adjacent oxygen atom, there is a competing interaction with a nitrate oxygen atom. All other image hydrogen atoms interact with nitrate oxygen atoms. In (L2H2)(tfs)2, the peripheral NH groups are protonated, the protonic hydrogen atoms interacting with tfs anions disposed above and below the macrocycle, making a tight [(L2H2)(tfs)2] cluster.