A dicobalt complex catalyzes N2 silylation with Me3SiCl and KC8 under 1 atm N2 at ambient temperature. Tris(trimethylsilyl)amine is formed with an initial turnover rate of 1 N(TMS)3/min, ultimately reaching a turnover number of ∼200. The dicobalt species features a metal-metal interaction, which we postulate is important to its function. Although N2 functionalization occurs at a single cobalt site, the second cobalt center modifies the electronics at the active site. Density functional calculations reveal that the Co-Co interaction evolves during the catalytic cycle: weakening upon N2 binding, breaking with silylation of the metal-bound N2 and reforming with expulsion of [N2(SiMe3)3](-).