The structure of potassium µ-nitrido-bis[aquotetrachlororuthenate(IV)], K₃[Ru₂NCl₈(H₂O)₂], has been determined by thee-dimensional X-ray crystal structure analysis. The compound crystallises in the monoclinic space group C2/m with Z= 2 in a unit-cell of dimensions a= 15·89, b= 7·34, c= 8·16 Å, β= 120·4°. Full-matrix least-squares refinement, with 697 visually estimated reflections, gave a final R value of 0·088.

The structure contains the nitrido-bridged complex ion [Ru₂NCl₈(H₂O)₂]^3–, which has 2/m crystallographic symmetry with the nitrogen atom lying on a centre of symmetry. The Ru–N distances are very short, 1·720 Å, indicating multiple bonding. The water molecules are trans to the nitrogen, with a fairly long Ru–O (water) distance of 2·18 Å. The four chlorines about each ruthenium are bent away from the nitrogen and towards the water molecule, such that the N–Ru–Cl angles are ca. 95°. The two independent Ru–Cl distances of 2·364 and 2·367 Å are normal. The potassium ions are co-ordinated to eight chlorines at distances in the range 3·20–3·36 Å.