A novel supermolecule [HgBr2(ptz)]2 _ HgBr2 (ptz¼phenothiazine) with uncoordinated inorganic salt HgBr2 presented in a 1D chain was prepared. The bulky ligand phenothiazine has unusual coordination mode with large steric inhibition perpendicular to the chain direction. The uncoordinated HgBr2 molecule was stabilized by multiple weak Hg_ _ _Br interactions and the whole structure was also stabilized by strong p–p interactions and N–H_ _ _Br hydrogen bonds to form 2D network.