Three closely related diruthenium triazeno complexes, Ru2[(p-tolyl)NNN(p-tolyl)]4(CH3CN) (1), Ru2(PhNNNPh)4 (2) and Ru2[(p-tolyl)NNN(p-tolyl)]4(CH3CN)·BF4 (3), have been synthesized and structurally characterized. Direct cocrystallization of Ru2[(p-tolyl)NNN(p-tolyl)]4 with CH3CN affords the dark red 1 in space group P4/n with a=14.851(3), c=11.942(7) Å, V=2634(2) Å3 and Z=2. The purple 2 was crystallized in space group P1 with a=13.720(5), b=15.901(4), c=10.388(4) Å, α=103.92(3), β=94.56(3), γ=99.11(3)°, V=2155(1) Å3 and Z=2. The dark green 3 was obtained by oxidizing Ru2[(p-tolyl)NNN(p-tolyl)]4 with Ag(CH3CN)4BF4, and crystallized in space group P2/n with a=13.280(2), b=16.816(5), c=13.095(4) Å, β=90.16(2)°, V=2924(2) Å3 and Z=2. The RuRu bond lengths determined through diffraction studies are 2.407(1), 2.3994(6) and 2.373(1) Å for 1, 2 and 3, respectively. The results of both magnetic susceptibility and EPR measurements on 3 consistently confirm a π*3 ground state configuration as previously predicted. © 1992.