Effects of intermolecular interactions on the H-1, C-13 and N-14 NMR chemical shifts of N,N-dimethylformamide dissolved in monosubstituted benzenes

H-1, C-13 and N-14 NMR chemical shifts have been used to monitor the diluti on process of N,N-dimethylformamide (DMF) in monosubstituted benzenes. Both the proton and carbon chemical shifts of non-equivalent methyl groups in D MF are spectacularly influenced by ASIS (Aromatic Solvent Induced Shift) ef fects at the low concentration of a solute. On the other hand, the destruct ion of DMF liquid structure itself is better seen when the C-13 chemical sh ift of a carbonyl carbon and the 14N shift are verified. A good correlation between the latter NMR chemical shifts has been found. It is shown on the basis of GIAO-CHF model calculations that the destruction of solute dipole- dipole dimers may be responsible for the increase of carbonyl carbon and ni trogen shielding constants of DMF in solvents.