A series of 5-alkyl/aryl-1,3 4  2 ,2,4,5-dithiadiazarsoles RAs(S 2 N 2 ) (R = Me, Et, were determined.

The molecular and crystal structure of 1-oxo-1,2,4,3,5-trithiadiazole () has been studied experimentally by the determination of the crystal structure and theoretically at the DFT/B1B95/aug-cc-pVTZ level of theory. The combination of the geometrical data with a number of properties of the title compound, consisting of orbital topologies, Hirshfeld charges and bond orders, aromaticity parameters and Fukui functions, led to a description of its structure, aromaticity and reactivity. In addition, the nature of the long sulfur-sulfur bond has been investigated. The bands in newly recorded infrared and Raman spectra have been assigned to the normal vibrations of the molecule, based on calculated vibrational data. The results of theoretical calculations of the 14N NMR chemical shifts have been compared to the experimentally obtained shifts.

Cp*Rh(S2N2) was prepared as a microcrystalline solid by using [S4N3]Cl in liquid ammonia or [nBu2Sn(S2N2)]2. It was characterised by NMR, IR and Raman spectroscopy andmass spectrometry. Low‐temperature crystal structures of Cp*Co(S2N2) and Cp*Ir(S2N2) were determined. The experimental characterisation of the Cp*M(S2N2) complexes was complemented by calculated geometries and bond orders at the DFT/B1B95 level of theory. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)