Abstract
A number of new NN'di(aryl)propene-1-amino-3-imine acid salts, their free bases and transition metal complexes are reported. Examination of the free dianils by infra-red and [1]H NMR spectroscopy shows that their alphabeta amino-imine isomer is present, at ambient temperatures, both in the solid state and in solution. The beta-diimine isomeric form has not been detected. In solution the free dianils exist in an equilibrium between the 'all-trans' and 'all-cis' geometrical isomers. The 'all-cis' isomer predominates in non-polar solvents whereas the 'all-trans' isomer is favoured in hydrogen bonding solvents. The bonding in the 'all-cis' isomer is discussed in terms of a cyclic delocalised pi electron system and a rapidly interchanging alphabeta double bond tautomeric system. Evidence is presented in favour of the latter model. Most of the acid salts reported exist wholly as the 'all-trans' isomer in solution. However, some of these,compounds are found to exist in both 'all-trans' and 'cis-trans' forms. The conditions that favour the occurrence of the 'cis-trans' isomer are reported. Monomeric bis [NN'di(aryl)propene-1-aminato-3-imine] metal(II) complexes are characterised and from a study of their electronic and infra-red spectra, and their magnetic moments, it is concluded that they have a distorted pseudo-tetrahedral stereochemistry. The electron impact mass spectra of all these compounds are described and possible fragmentation schemes are presented.