An unprecedented class of organo-dimetallic compounds, monotitanium (Ti/Li) and bis-titanium (Ti/Ti) complexes bridged by 2-butene tetraanionic ligands, were obtained from the reaction of dilithio reagents 1 with TiCl2 (TMEDA) or TiCl4, respectively. The Ti/Li complex could be transformed to the Ti/Ti complex when treated with TiCl3 (THF)(3). Mechanistic study demonstrated that the dilithio reagents 1 acted as both reductant and oxidant in the reaction process.