Quinazoline electron density diagram

The observed dipole moments of quinazoline and 2-methyIquinazoline in benzene are 2.2 D, in good agreement with calculated values (2.55 D). Calculated electron densities vary markedly with the method used. The electron density diagram which gives dipole moments in agreement with experiment is shown below. 

Electron-density calculations for quinazoline (which has no symmetry) vary markedly with the method used. The diagram (6) has the same bases as that given for pyrimidine above it will be observed that the 2- and 4-positions in quinazoline are comparable with the corresponding positions in pyrimidine and that the aromatic carbon atoms (C-5-C-8) in quinazoline are roughly comparable with C-5 in pyrimidine (67MI21300). The dipole moment of quinazoline does not appear to have been measured, but that of 2-methylquinazo-line is 2.2 D. 

The electron distribution diagrams for pyrimidine (6), quinazoline (7) and perimidine (8), and aceperimidylene (9) show gain or loss of rr-electrons at each atom (Figure 1). The values for pyrimidine are calculated by the VESCF method. It is evident that there is a considerable depletion of electron density at the 2- and 4-/6-positions, and a slight depletion at the 5-position. There is a greatly enhanced density at the A-atoms. 

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