Dinitrogen formation by oxidative intramolecular N---N coupling in cis,cis-[(bpy)2(NH3)RuORu(NH3)(bpy)2]4+.

The (15)N-labeled diammine(mu-oxo)ruthenium complex cis,cis-[(bpy)(2)(H(3)(15)N)Ru(III)ORu(III)((15)NH(3))(bpy)(2)](4+) ((2-(15)N)(4+)) was synthesized from cis,cis-[(bpy)(2)(H(2)O)Ru(III)ORu(III)(H(2)O)(bpy)(2)](4+) by using ((15)NH(4))(2)SO(4) and isolated as its perchlorate salt in 17% yield. A 1:1 mixture of (2-(15)N)(4+) and nonlabeled cis,cis-[(bpy)(2)(H(3)(14)N)Ru(III)ORu(III)((14)NH(3))(bpy)(2)](4+) were electrochemically oxidized in aqueous solution. The gaseous products (14)N(2) and (15)N(2) were formed in equimolar amounts with only a small amount of (14)N(15)N detected. This demonstrates that dinitrogen formation by oxidation of the diammine complex proceeds by intramolecular N---N coupling.