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

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 F3CSO3- (‘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 NH2+ 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 NH2+ 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.

Graphical abstractThe results of an investigation of the solid state structures and hydrogen-bonding patterns present in two mixed oxygen–nitrogen donor macrocyclic salts incorporating nitrate and triflate counterions is presented.Figure optionsDownload full-size imageDownload as PowerPoint slide