Rhodium carbonyl clusters with interstitial nitrogen atoms. Part 1. Crystal and molecular structure of the bis(triphenylphosphine)iminium salt of the anion ennea-µ-carbonyl-hexacarbonyl-µ6-nitrido-polyhedro-hexarhodate(1–)

Abstract

The title compound, [N(PPh₃)₂][Rh₆N(CO)₁₅], crystallizes in the triclinic space group P, with cell constants a= 19.841(5), b= 9.156(3), c= 16.066(5)Å, α= 95.88(3), β= 70.12(3), γ= 87.99(3)°, and Z= 2. The structure solution and refinements have been based on 6 401 significant single-crystal X-ray counter data, the final conventional R value being 0.034. The anion contains a trigonal prism of rhodium atoms with a central nitrogen atom. The Rh–Rh bond lengths belong to two classes: those within the two basal triangles (mean 2.763 Å) and the interbasal ones (mean 2.828 Å). The Rh–N interactions have a mean value of 2.130 Å. Six carbonyl ligands are bound terminally, one per rhodium atom (mean Rh–C and C–O 1.863 and 1.134 Å), and nine bridge all the polyhedral edges (mean Rh–C and C–O 2.095 and 1.153 Å). The structure is discussed in comparison with those of related carbido-carbonyl cluster species.