Superhalogen Species of Titanium Oxide Related Clusters Generated by Laser Ablation.

Negative ion mass spectrometry can serve as an effective and easy way to find new candidates of superhalogen species. In order to investigate superhalogen properties of polytitanium clusters, the laser ablation mass spectrum of TiO ₂ was obtained with a Fourier transform ion cyclotron resonance mass spectrometer. Density functional theory calculations were also performed in this study. Species of [(TiO ₂ ) _x (H ₂ O) _y OH] ^- ( x = 1-8, y = 1-3) were observed in the mass spectrum. Among them, the intensities of [(TiO ₂ ) ₄ (H ₂ O)OH] ^- , [(TiO ₂ ) ₄ (H ₂ O) ₂ OH] ^- , [(TiO ₂ ) ₃ (H ₂ O) ₂ OH] ^- , and [(TiO ₂ ) ₅ (H ₂ O) ₂ OH] ^- are remarkable. The structures of these species and their neutral counterparts are studied on the level of B3LYP/Lanl2dz/6-311++G(2d, 2p). Results show that the electron affinities (EAs) of the neutral clusters are all higher than that of the chlorine atom and (TiO ₂ ) ₄ (H ₂ O) ₂ OH has the highest electron affinity value at 6.23 eV. This series of polytitanium superhalogens not only indicate that the OH might be applied as an effective superhalogen ligand but also show the potential of metal titanium in the design of novel superhalogen compounds.