title: Molecular structure and bonding in octamethylporphyrin tin(II), SnN4C28H28.
abstract: Gas-phase electron diffraction was applied for the molecular structure determination of octamethylporphyrin tin(II), SnN(4)C(28)H(28), at the temperature of 706(10) K. The molecule was found to possess C(4v) symmetry with the Sn atom 1.025(30) Å above the plane of the N atoms and the following main internuclear distances (r(h1), Å): Sn-N = 2.301(9), C(α)-N = 1.360(8), C(α)-C(β) = 1.453(4), C(α)-C(m) = 1.395(4), C(β)-C(CH3) = 1.498(4). Quantum chemical calculations, DFT (B3LYP, BP86, PBE, PBE0) with cc-pVDZ, cc-pVTZ and cc-pVQZ basis sets reproduce the experimental bond distances with accuracy within 0.03 Å. According to NBO(B3LYP/cc-pVTZ) analysis, the direct donation gives a prevailing contribution to Sn-N bonding, decreasing the net charge on Sn from formal +2 to +1.28. The substitution effects at the pyrrole rings are discussed. The ability of different theoretical methods to predict the structure of this compound is analyzed.
authors.affiliation: Ivanovo State University of Chemistry and Technology, Department of Physics, Engels av 7, 153000 Ivanovo, Russia. girichev@isuct.ru
authors.forename: Georgiy V
authors.initials: GV
authors.lastname: Girichev
authors.forename: Nina I
authors.initials: NI
authors.lastname: Giricheva
authors.forename: Oscar I
authors.initials: OI
authors.lastname: Koifman
authors.forename: Yury V
authors.initials: YV
authors.lastname: Minenkov
authors.forename: Alexander E
authors.initials: AE
authors.lastname: Pogonin
authors.forename: Alexander S
authors.initials: AS
authors.lastname: Semeikin
authors.forename: Sergey A
authors.initials: SA
authors.lastname: Shlykov