Geometries of monomers and oligomers of a platinum polyyne and its free ligands were optimized using density functional theory with B3LYP hybrid functional. The LANL2DZ basis set was used for Pt and the 6-31G* for other atoms in geometry optimizations. The electronic structures of these compounds were analyzed using Stuttgart/Dresden ECPs (SDD) basis set for metal atoms and 6-311G* for others. The polymerization has very little effect on the bond lengths and by introducing the metal, the acetylide bond length increases slightly. The strong overlap between metal spx orbitals and σpx orbitals of acetylides results in localized σ bonding. The hybridization between the ligand pπ orbitals and the platinum dπ orbital resulted in the π-conjugation enhancement. This conjugation enhancement causes some effects such as the highest-occupied molecular orbital–lowest-unoccupied molecular orbital gap reduction and charge transfer characteristic of low-energy vertical transitions. © 2013 Wiley Periodicals, Inc.