Tin(II) Phthalocyaninate and Tin(IV) bis-Phthaloc Yaninate: A Quantum Chemical Study

The structural parameters of tin(II) phthalocyaninate PcSn and tin(IV) bis-phthalocyaninate Pc₂Sn as well as of their cations are determined by B3LYP/SDD and PBE0/SDD quantum chemical methods. The PcSn molecule is characterized by C_4v symmetry, and SnN bond lengths are 2.307/2.299 ? (B3LYP/PBE0). The Sn nucleus is by 1.11 ? (B3LYP, PBE0, single crystal X-ray diffraction analysis) higher than the plane of four neighboring nitrogen nuclei. The “hindered” configuration (D _4d symmetry) with a high (27–30 kcal/mole) internal rotation barrier corresponds to the Pc₂Sn energy minimum. The calculated equilibrium lengths of eight equivalent SnN bonds of 2.366/2.347 (B3LYP/PBE0) are similar to the average SnN bond length of 2.347 ? (single crystal X-ray diffraction). Vertical and adiabatic ionization potentials are calculated: I^v 6.40/6.48 eV, I^A 6.38/6.45 eV for PcSn and I^v 5.63/5.66 eV, I^A 5.60/5.63 eV for Pc₂Sn.