Crystal structures and conformational behavior in solution of two isomeric dicyanobiphenyls

Two dicyanobiphenyls, 3-phenylphtalodinitrile (1) and 4-phenylphtalodinitrile (2) were synthesized by Pd(II)-catalyzed cyanation of relevant dichlorobiphenyls (РСВ5 and PCB12), and their structures were determined by single crystal X-ray diffraction. The dihedral angle between the phenyl rings is equal to 51.50° in o-substituted molecule 1 and 30.76° in 2. To rationalize the conformational differences between two molecules the optimized geometries and potential energy curves (relative energy vs. torsion angle) were calculated at the B3LYP/6-31+G(d) level of theory using the PCM solvation model. The electronic properties of substituents were found to affect slightly on the conformational characteristics of the substituted biphenyls in solution.