Crystal and molecular structure of bis(tetraethylammonium) 1,2;2,3;3,1-tri-μ-hydrido-μ 3,-oxo-1,1,1,2,2,2,3,3,3-enneacarbonyl-triangulo-trirhenate(2-)

The title compound, [NEt4]2[Re3H3O(CO)9], crystallizes in the orthorhombic space group Pnma with cell constants a = 15.05(2), b = 12.32(1), c = 18.35(2) Å, Z = 4. The structure has been determined by vector methods from single-crystal X-ray counter data and refined by block-diagonal least squares to a conventional R value of 0.032 for 1 147 independent reflections. The anion contains an equilateral triangle of metal atoms (mean Re-Re 2.968 Å) capped by a symmetric triply bridging oxo-ligand (mean Re-O 2.12 Å). The carbonyl groups are all terminally bonded, three for each rhenium atom (mean Re-C and C-O 1.88 and 1.18 Å). The overall idealized anion symmetry is C3v. The carbonyl disposttion implies that the three hydrido-ligands lie in bridging positions on the Re3 triangular edges.