Group 4 metal atom reactions with CF3Cl, CFCl3, CF3Br, and CF3I:: A matrix infrared spectroscopic and DFT investigation of competitive α-halogen transfer to form triplet XC ÷ MX3 complexes

Laser-ablated group 4 transition metal atoms react with (CXX32)-X-1 (X = F, Cl, Br, or I) to form triplet state (XC)-C-1 divided by MX32 and (XC)-C-2 divided by(MXX22)-X-1 complexes, which are identified by their infrared spectra, carbon-13 isotopic shifts, and comparison to density functional vibrational frequency calculations. The higher energy product with more heavier halogen migration converts to the lower energy product with more alpha-F transfer on UV irradiation. Two features are of particular interest in these product complexes: The first is the presence of a very strong C-X bond, and the second is that the two unpaired electrons on carbon are shared with the transition metal center, forming an electron-deficient triple bond. Comparisons are made to the analogous reaction products with CF4, CCl4, and CF2Cl2.