Infrared Spectra of CH<sub>3</sub>–MH through Methane Activation by Laser-Ablated Sn, Pb, Sb, and Bi Atoms

2012-08-23T00:00:00Z (GMT) by Han-Gook Cho Lester Andrews
Methane activation has been carried out by laser-ablated Sn, Pb, Sb, and Bi atoms. All four metals generate the insertion complex (CH<sub>3</sub>–MH), but subsequent H-migration from C to M to form CH<sub>2</sub>–MH<sub>2</sub> and CH–MH<sub>3</sub> complexes is not observed. Our previous and present experimental and computational results indicate that the higher oxidation state complexes become less favored with increasing atomic mass in groups 14 and 15, which is opposite the general trend found for transition metals. The C–H bond insertion evidently occurs during reaction on sample condensation, and the product dissociates on broad-band photolysis afterward. The insertion complex contains a near right angle C–M–H moiety because of high p contribution from the metal center to the C–M and M–H bonds unlike many transition-metal analogues. The computed methylidene structures for these main group metals are not agostic possibly because of the absence of valence d-orbitals.