The synthesis and structural characterization of the complex Ru 2 (CN)(μ-DPhF) 4 (1) (DPhF=N,N ' -diphenylformamidinate) is reported. The reactivity of the axial position of Ru 2 Cl(μ-O 2 CMe)(μ-DPhF) 3 is studied and the crystal structures of Ru 2 (N 3 )(μ-O 2 CMe)(μ-DPhF) 3 (2) and Ru 2 (NCS)(μ-O 2 CMe)(μ-DPhF) 3 (3) are described. The isolation of Ru 2 Cl(μ-N 3 Ph 2 ) 4 (4) and Ru 2 Cl 2 (μ-N 3 Ph 2 ) 4 (5), and the crystal structure determination of complex 4, which constitutes the first example of a chlorotriazenido derivative, are also reported. Each complex forms discrete dinuclear molecules in the solid state, having (each diruthenium unit) one free axial position. The shortest Ru-Ru distance [2.286(2) A] is observed in the cyano derivative (1) and the longest [2.4747(11) A] is found in the triazenido complex (4). The azido (2) and isothiocyanato (3) derivatives show similar Ru-Ru distances of 2.3182(11) and 2.3159(4) A, respectively. Complexes 2 and 4 display magnetic moments at room temperature corresponding to three unpaired electrons in agreement with the σ 2 π 4 δ 2 (π * δ * ) 3 ground-state configuration, whereas compounds 1 and 3 are low spin complexes with only one unpaired electron. Only very few examples of low spin diruthenium(II,III) species have been previously characterized. The diruthenium(III) compound 5 is diamagnetic.