Two novel types of transition-metal-containing liquid crystals, bis(p-n-koxydithiobenzoato)nickel(II) (abbreviated as (CnO-DTB)2Ni), and (p-n-alkoxydithiobenzoato)(p-n-alkoxyperthiobenzoato)nickel(II) (abbreviated as (CnO-DTB)(CnO-PTB)Ni), were synthesized. It was found that the (CnO-DTB)2Ni complex forn= 8 hassmecticH and C mesophases, and that the (CnO-DTB)2Ni complexes forn= 4 and 8 easily transform into the corresponding monoperthio complexes,nO-PTB)Ni, by heating at temperatures between 230°C and 285°C. It was confirmed that the transformation originates from an intermolecular reaction between the (CnO-DTB)2Ni complexes at high temperatures, and that the origin of the extra sulphurs in the resulting (CnO-DTB)(CnO-PTB)Ni complexes is the neighbouring (CnO-DTB)2Ni complexes. Interestingly, each of the (CnO-DTB)(CnO-PTB)Ni complexes (n= 4 and 8), hasnematicmesophase and exhibits a unique double melting behaviour via the nematic phase, which is the first example in liquid crystals. The reversible transformation between theblue smectic rod-like(CnO-DTB)2Ni complex and thered nematic Λ-like(CnO-DTB)(CnO-PTB)Ni complex is possible.