Molybdenum–nitrogen multiple bonds: the crystal and molecular structures of tris(NN-diethyldithiocarbamato)nitridomolybdenum and tris(NN-dimethyldithiocarbamato)thionitrosylmolybdenum

Abstract

The crystal and molecular structures of the title compounds have been determined by single-crystal X-ray analyses, The nitride is monoclinic, space group P2₁/c, with a= 10.844, b= 13.253, c= 17.317 Å, β= 90.12°, and Z= 4. The structure has been refined to an R value of 0.054 5 using 1 695 observed intensity data measured on an automatic diffractometer. The thionitrosyl is triclinic, space group P, with a= 9.090, b= 9.327, c= 12.080 Å, α= 95.01. β= 91.95, γ= 96.16°, and Z= 2. Structure refinement using 1 907 observed data measured on a manual diffractometer has given an R value of 0.068. Both compounds have a pentagonal-bipyramidal molecular structure with the nitrogen ligands axial and with one axial/equatorial and two equatorial/equatorial chelating dithiocarbamates. The geometry of the thionitrosyl group (Mo–N 1.738, N–S 1.592 Å) suggests a close analogy with the linear nitrosyl [NO]⁺ ligand. In the nitride, the Mo–N distance of 1.641 Å is consistent with its formulation as a triple bond. In both compounds, the axial Mo–S bond, trans to the π-bonding ligand, is lengthened with the nitride showing the largest effect. This particular feature, together with other aspects of the distortion of the pentagonal-bipyramidal co-ordination sphere, are discussed in relation to other systems with comparable structures.