Is diatomic nitrogen a dipole?
No. A dipole would be an H20 molecule, for example, with some + on one end and some - on the other. Even in liquid form where the molecule probably isn't so simple, water responds to magnetism. N2 would have a balanced charge.
This gets into the theory of how magnetism can arise from a material with no net charge. What is the cause of magnetism? a typical question from the realm of science.