Physico-chemical and structural characterization of the binary system phosphoric acid-N,N-dimethylformamide.

The binary phosphoric acid (H(3)PO(4))-N,N-dimethylformamide (DMF) system has very different physico-chemical properties depending on composition. This paper summarizes the physico-chemical data newly collected and reported previously on the H(3)PO(4)-DMF system, and proposes structural models for the different regions of composition. The internal hydrogen bonding between pairs of phosphoric acid molecules in cyclic dimeric units is very important as well as the role of the DMF oxygen as hydrogen bond acceptor linking the dimeric phosphoric acid units into polymeric layers and three-dimensional networks.