CONFORMATIONAL BEHAVIOR OF HYDROXAMIC ACIDS - AB-INITIO AND STRUCTURAL STUDIES

The conformational behaviour of a series of monohydroxamic acids, p-RC (6)H(4)CONR'OH (R = Me, R' = H, Me; R = MeO, R' = H, Me; R = NO2, R' = H), and a series of dihydroxamic acids, (CH2)(n)(CONR'OH)(2) (n = 3-8 , 10, R' = H and n = 7, R' = Me), in methanol, DMSO and chloroform and in the solid state has been examined using IR and NMR spectroscopy, X -Ray crystal structure determinations of p-MeC(6)H(4)CONMeOH and the m onohydrate of glutarodihydroxamic acid (n = 3) together with ab initio molecular orbital calculations for several hydrated and unhydrated hy droxamic acids have been performed. Hydrogen bonding effects are shown to be important in both the solid state and solution, The cis(Z) conf ormation of the hydroxamate group(s) (CONHOH) is preferentially stabil ized by hydrogen bonding with water molecules.