On thio-substituted N-heterocyclic arsines

Metathesis of N-heterocyclic chloroarsines with sulfur-based nucleophiles furnished thio-substituted 1,3,2-diazarsolidines and 1,3,2-diazarsolenes. Crystallographic and NMR spectroscopic studies revealed that a thiocyanato-diazarsolene exhibits a salt-like structure composed of weakly interacting thiocyanate and arsenium ions, while the remaining products formed neutral molecules. The structural data indicate that the heterocyclic framework induces an elongation of exocyclic As-S bonds that is more prominent in diazarsolenes than in diazarsolidines and parallels the bond polarisation effect established for N-heterocyclic phosphines. The NMR data suggest that diazarsolenes undergo facile inversion of the pyramidal configuration at arsenic, which was successfully modelled by DFT studies.

Automated summary

Metathesis reaction of N-heterocyclic chloroarsines with sulfur-based nucleophiles leads to the formation of thio-substituted compounds, with a thiocyanato-diazarsolene exhibiting a salt-like structure and the remaining products as neutral molecules. Thio-substitution results in elongation of exocyclic As-S bonds in the heterocyclic framework, particularly more prominent in diazarsolenes.