Theoretical Study on Structures and Aromaticities of P5‐ Anion, [Ti(η5‐P5)]‐ and Sandwich Complex [Ti(η5‐P5)2]2‐.

Abstract

The equilibrium geometries, energies, harmonic vibrational frequencies, and nucleus independent chemical shifts (NICSs) of the ground state of P5- (D5h) anion, the [Ti (η5−P5)]- fragment (C5v), and the sandwich complex [Ti(η5−P5)2]2- (D5h and D5d) are calculated by the three-parameter fit of the exchange-correlation potential suggested by Becke in conjunction with the LYP exchange potential (B3LYP) with basis sets 6-311+G(2d) (for P) and 6-311+G(2df) (for Ti). In each of the three molecules, the P−P and Ti−P bond distances are perfectly equal: five P atoms in block P5- lie in the same plane; the P−P bond distance increases and the Ti−P bond distance decreases with the order P5-, [Ti(η5−P5)2]2-, and [Ti (η5−P5)]-. The binding energy analysis, which is carried out according to the energy change of hypothetic reactions of the three species, predicts that the three species are all very stable, and [Ti (η5−P5)]- (C5v), more stable than P5- and [Ti(η5−P5)2]2- synthesized in the experiment, could be synthesized...