Stannylenes: structures, electron affinities, ionization energies, and singlet-triplet gaps of SnX2/SnXY and XSnR/SnR2/RSnR′ species (X; Y = H, F, Cl, Br, I, and R; R' = CH3, SiH3, GeH3, SnH3).

Systematic computational studies of stannylene derivatives SnX(2)/SnXY and XSnR/SnR(2)/RSnR' were carried out using density functional theory. The basis sets used for H, F, Cl, Br, C, Si, and Ge atoms are of double-ζ plus polarization quality with additional s- and p-type diffuse functions, denoted DZP++. For the iodine and tin atoms, the Stuttgart-Dresden basis sets, with relativistic small-core effective core potentials (ECP), are used. All geometries are fully optimized with three functionals (BHLYP, BLYP, and B3LYP). Harmonic vibrational wavenumber analyses are performed to evaluate zero-point energy corrections and to determine the nature of the stationary points located. Predicted are four types of neutral-anion separations, plus adiabatic ionization energies (E(IE)) and singlet-triplet energy gaps (ΔE(S-T)). The dependence of all three energetic properties upon choice of substituent is remarkably strong. The EA(ad(ZPVE)) values (eV) obtained with the B3LYP functional range from 0.70 eV [Sn(CH(3))(2)] to 2.36 eV [SnI(2)]. The computed E(IE) values lie between 7.33 eV [Sn(SnH(3))(2)] and 11.15 eV [SnF(2)], while the singlet-triplet splittings range from 0.60 eV [Sn(SnH(3))(2)] to 3.40 eV [SnF(2)]. The geometries and energetics compare satisfactorily with the few available experiments, while most of these species are investigated for the first time. Some unusual structures are encountered for the SnXI(+) (X = F, Cl, and Br) cations. The structural parameters and energetics are discussed and compared with the carbene, silylene, and germylene analogues.