Reaction of (LRuCl3)-Cl-III (L = 1,4,7-trimethyl-1,4,7-triazacyclononane) with 1,2-phenylenediamine (opdaH(2)) in H2O in the presence of air affords [LRuIII(bqdi)(OH2)](PF6) (1), where (bqdi) represents the neutral ligand o-benzoquinone diimine. From an alkaline methanol/water mixture of 1 was obtained the dinuclear species [{LRuII(bqdi)}(2)(mu-H3O2)](PF6)(3) (1a). The coordinated water molecule in 1 is labile and ran be readily substituted under appropriate reaction conditions by acetonitrile, yielding [LRuII(bqdi)(CH3CN)](PF6)(2) (2), and by iodide and azide anions, affording [LRuII(bqdi)I](PF6). 0.5H(2)O (3) and [LRuII(bqdi)(N-3)] (PF6). H2O (4), respectively. Heating of solid 4 in vacuum at 160 degrees C generates N-2 and the dinuclear, nitrido-bridged complex [{LRu(o-C6H4(NH)(2))}(2)(mu-N)](PF6)(2) (5). Complex 5 is a mixed-valent, paramagnetic species containing one unpaired electron per dinuclear unit whereas complexes 1-4 are diamagnetic. The crystal structures of 1, 1a . 3CH(3)CN, 3, 4 . H2O, and 5 . 3CH(3)CN . 0.5(toluene) have been determined by X-ray crystallography : 1 crystallizes in the monoclinic space group P2(1)/m, Z = 2, with a = 8.412(2) Angstrom, b = 15.562(3) Angstrom, c = 10.025 Angstrom, and beta = 109.89(2)degrees; 1a . 3CH(3)CN, in the monoclinic space group C2/c, Z = 4, with a = 19.858(3) Angstrom, b = 15.483(2) Angstrom, c = 18.192(3) Angstrom, and beta = 95.95(2) degrees, 3, in the orthorhombic space group Pnma, Z = 4, with a = 18.399(4) Angstrom, b = 9.287(2) Angstrom, and c = 12.052(2) Angstrom, 4 . H2O, in the monoclinic space group P2(1)/c, Z = 4, with a = 8.586(1) Angstrom, b = 15.617(3) Angstrom, c = 16.388(5) Angstrom, and beta = 90.84(2)degrees; and 5 . 3CH(3)CN . 0.5(toluene), in the monoclinic space group P2(1)/c, Z = 4, with a = 15.003(3) Angstrom, b = 16.253(3) Angstrom, c = 21.196(4) Angstrom, and beta = 96.78(3)degrees. The structural data indicate that in complexes 1-4 the neutral o-benzoquinone diimine ligand prevails. In contrast, in 5 this ligand has predominantly o-phenylenediamide character, which would render 5 formally a mixed-valent (RuRuV)-Ru-IV species. On the other hand, the Ru-N bond lengths of the Ru-N-Ru moiety at 1.805(5) and 1.767(5) Angstrom are significantly longer than those in other crystallographically characterized Ru-IV=N=Ru-IV units (1.72-1.74 Angstrom). It appears that the C6H4(NH)(2) ligand in 5 is noninnocent and that formal oxidation state assignments to the ligands or metal centers are not possible.