Synthesis, Theoretical Studies of N1,N2,1,2-Tetraphenylethane-1,2-Diimine and Their Derivatives

Abstract

N¹,N²,1,2-tetraphenylethane-1,2-diimine(1),N¹,N²-bis(2-bromophenyl)-1,2diphenylethane-1,2-diimine(2) and N¹,N²-bis(4-bromophenyl)-1,2-diphenylethane-1,2-diimine(3) were synthesised and studied theoretically. The bond lengths, bond angles, dihedral angles and close contact of atoms were calculated. There are variable results for each compound. Internal coordinate of the three compounds were showed that the atoms around the double bond were in R and S configuration and the angle type was dihedral in most of atoms. The molecular mechanics force field (MMFF94) energy and gradient for (1), (2) and (3) were also calculated. The results showed that the total energy for this frame were (746.902, 1223.418 and 1235.345) kcal/mol respectively and the RMS gradients were 80.761, 175.979 and 178.38 respectively. The MMFF94 minimization iteration was also calculated which equal to 455, 500 and 500 and the final energy for (1), (2) and (3) were (120.525, 153.35 and 117.306) kcal/mol respectively. Though, the molecular mechanics (MM2) minimization of (1), (2) and (3) were also calculated and the total energy were (78.4465, 85.3592 and 74.7126) kcal/mol. the results were showed the difference between the three compounds and the effect of substitution in their results, the compound (2) was gave high total energy higher than (1) and (3) because the bulky substituted Br in ortho position which near to the nitrogen of imine group can effective by steric effect and this can explain the high value of strain energy (E). High dipole/dipole value was observed in compound (2) which was also higher than (1) and (3) and the later was higher than (1) which explains the effect of substituted group and their position in the structure properties. The best minimization either use MMFF94 or MM2 were observed in compound (3) which gave lower total energy than (1) and (2). The MMFF94 minimization and MM2 minimization were indicated the steric effect of o-Br in compound (2).

Keywords: Internal coordinate, Molecular mechanics, ligand.