The complexes of arsenic(III), antimony(III), bismuth(III), tin(II) and lead(II) with monomethylsubstituted piperidinodithiocarbamates of general formula M(Rdtc)3 and M(Rdtc)2 have been prepared and characterized by spectroscopic methods. The results of the spectroscopic studies indicate that the dithiocarbamate ligands are always bidentate, in both the 1:3 and the 1:2 complexes. All the complexes are nonconducting in DMF solution. The thermal behaviour of the complexes has been investigated by TG and DTG techniques. The molecular weight determinations indicate that the trisdithiocarbamates of arsenic and antimony are monomeric, while the bismuth trisderivatives tend to dimerize: polymeric structures can be suggested for the tin(II) and lead(II) compounds.