Crystallographic analysis of some Schiff bases derived from 4-Methoxy Salicylaldehyde

The molecular and crystal structure of the compounds `(E)-2-((4-chlorophenylimino)methyl)-5-methoxyphenol? and `(E)-5-methoxy-2-((o-tolylimino)methyl)phenol? have been determined by the method of single crystal X-ray diffraction and the quantitative aromaticities of the molecule?s associated fragments have been evaluated via HOMA and HOMHED index.The compound `(E)-2-((4-chlorophenylimino)methyl)-5-methoxyphenol? crystallizes in monoclinic system. 1210 observed reflections that possesses the condition I > 2sigma(I) among reflection datas have been solved with direct methods and structure refinement was accomplished by the value of R=0,0392. It is detected that the compound is stable under O-H???N type intra-molecular and C-H???O type inter-molecular interactions. The HOMA and HOMHED values of the molecule?s phenol, phenyl and chelate rings were calculated and are found as 0,967; 0,752; 0,942 respectively.The compound `(E)-5-methoxy-2-((o-tolylimino)methyl)phenol? crystallizes in monoclinic system. 1836 observed reflections that posses the condition I >2sigma(I) among reflection datas have been solved with direct methods and structure refinement was accomplished by the value of R=0,0326. It is detected that the compound is stable under O-H???N type intra-molecular, C-H???pi and pi???pi type inter-molecular interactions. The HOMA and HOMHED values of the molecule?s phenol, phenyl and chelate rings were calculated and are found as 0,931; 0,754; 0,965 respectively. H-bridged chelate ring assisted pi-stacking interactions discovered in 2012 are also observed in the crystal structure of the compound.Keywords: Schiff base, HOMA, HOMHED, pi-pi interactions.