Polycarbosilanes obtained by the Wurtz method or Grignard synthesis were converted by protodesilylation with trifluoromethanesulfonic acid to triflate-substituted derivatives. Reactions of these polymeres with nucleophiles led to novel functionally substituted polycarbosilanes. Polycarbosilanes with a regular alternating arrangement of silicon and carbon atoms, however, could not be obtained by this procedure. Such polymers were prepared by reactions of bis(trifluoromethylsulfonyloxysilyl) methanes with dinucleophiles. All syntheses are characterized by a high regioselectivity and high yields at low temperatures in short reaction times. The structures of the polymers were proven by NMR spectroscopy (Si-29, C-13, H-1).