Infrared spectra of CH3-MF and several fragments prepared by methyl fluoride reactions with laser-ablated Cu, Ag, and Au atoms.

Reactions of laser-ablated, excited group 11 metal atoms with CH(3)F isotopomers have been carried out, leading to the generation of CH(3)-MF and CH(2)F-M complexes for Cu, Ag, and Au in addition to smaller complexes for gold. The products in the infrared spectra identified on the basis of their frequencies, isotopic shifts, and correlation with DFT calculated frequencies reveal that M-F insertion by the coinage metals and H atom release readily occur. The relatively low dissociation energies of CH(3)-AuF to give several smaller Au complexes are consistent with the observation of these fragments. The C-Au bonds of CF-AuH and CH(2)-AuF exhibit considerable π character, and the methylidene CH(2)-AuF contains a true double bond. In contrast, the bond orders of CH(2)-Au and CH(2)-AuH are lower, indicating that F bonded to Au contracts the gold 5d orbitals for better overlap with the carbon 2p orbital for π bonding.