Journal of Physical Chemistry A vol:102 issue:37 pages:7308-7313
The structures and energies of the binary dititanium tricarbide Ti2C3 in the lowest singlet, tripler, and quintet states have been investigated by density functional theory using the hybrid B3LYP functionals. Geometries and frequencies for a number of isomeric structures are presented at the B3LYP level. A pentagonal structure with a C-2 unit at the base and a carbon at the apex, Xs, is found to be the global Ti2C3 minimum. Cyclic structures V-VIII derived from the 2-fold addition of titanium to the most stable "fan" and "kite" isomers of TiC3 are characterized as higher energy local minima. Linear structures I-IV with all probable relative positioning of the two titanium atoms have been identified as higher order saddle points with respect to the degenerate bending vibration, except for the cumulene-like valence structure I. Cyclic structures are energetically favored over the linear structures. A comparison with the penta-aromic group IVA silicon-carbon clusters is given, where appropriate.