The six-electron oxidation of two nitrides to N-2 is a key step of ammonia synthesis and decomposition reactions on surfaces. In molecular complexes, nitride coupling has been observed with terminal nitrides, but not with bridging nitride complexes that more closely resemble catalytically important surface species. Further, nitride coupling has not been reported in systems where the nitrides are derived from N-2. Here, we show that a molecular diiron(II) diiron(III) bis(nitride) complex reacts with Lewis bases, leading to the rapid six-electron oxidation of two bridging nitrides to form N-2. Surprisingly, these mild reagents generate high yields of iron(I) products from the iron(II/III) starting material. This is the first molecular system that both breaks and forms the triple bond of N-2 at room temperature. These results highlight the ability of multi-iron species to decrease the energy barriers associated with the activation of strong bonds.