Abstract The i.r. and Raman spectra of monomeric AsVi 3, SbVi 3, Vi 3AsHal 2 and Vi 3SbHal 2 (Vi = CH 2 = CH-, Hal = F, Cl) have been recorded and assigned. According to these data the compounds have trigonal pyramidal and trigonal bipyramidal structures, respectively, probably with slightly twisted vinyl groups. The 1H- and 13C-NMR spectra of the products have been measured in different solvents and at different temperatures. For the quantum mechanical calculations of these NMR spectra a modified BASIC version of the known fortran programme LAOCOON III was used.