Dipole moments of molecules of 1, 3, 5-triaryl-δ2-pyrazolines

The dipole moments of 1, 3, 5-triphenylpyrazole and a number of pyrazoline derivatives are determined. The presence of a C=C double bond in pyrazole does not lead to formation of a single electron system in the heterocyclic ring. Comparison of found and calculated vector dipole moments confirms the appreciable effect of aromatic groups at position 1, and especially at position 3, and the slight effect at position 5.