Matrix Infrared Spectroscopic and Theoretical Studies for Products Provided in Reactions of Sn with Ethane and Halomethanes.

Tin insertion products (oxidation state 2+) were observed in reactions of laser-ablated Sn atoms with ethane, and halomethanes in excess argon, parallel to the Pb reactions. The CSnX bond angles of the observed Sn complexes are close to right angles, and natural bond orbital calculations show that Sn also utilizes mostly its p-orbitals to make chemical bonds. Bridged Sn complexes [CX2(X)-SnX] were also provided in reactions of tetrahalomethanes via photo-isomerization of the insertion products, showing that the p-orbitals of Sn are more accessible than those of Pb. These products were identified from the matrix infrared spectra on the basis of isotopic shifts and density functional theory frequencies. Considering the previously reported high-oxidation-state products of the lighter group 14 elements and the Pb products with primarily oxidation state 2+ because of the relativistic effects, the observed Sn complexes show a trend that the high-oxidation-state complexes are less favored with increasing atomic mass in group 14, which is opposite to that observed in transition-metal columns.