I don't know of any. The two most common combinations of nitrogen are the oxides (NOx) and the hydrides (amines, ammonia). Both require activation energies (temperatures and pressures) that would not be available at LN2 temperatures and pressures.
LN2 is primarily valuable as a way to transport large amounts of nitrogen. It is also used extensively as a cryogenic coolant in many industries. But I have not heard of any reactions that can take place in LN2 directly.
Best regards,
Steven
