Matrix photochemistry of gallium and indium atoms (M) in the presence of methane: Formation and characterization of the divalent species CH3MH and univalent species CH3M

IR and UV/vis spectroscopic measurements have been used to chart the reacti ons set in train by irradiating methane-doped argon matrices containing gal lium or indium atoms, first with light having lambda = 200-400 nm, and subs equently with broad-band UV-visible light. Assignments of the LR absorption bands are made and their carriers characterized on the basis of D and C-13 substitution and by comparison either with the vibrational properties of r elated molecules or with those forecast by DFT calculations, Photoexcitatio n at lambda = 200-400 nm results in insertion of the group 13 metal atom in to a C-H bond to form the angular monomethylmetal hydride molecule, CH3MH ( M = Ga, In). This product is not photostable. but decomposes on exposure to radiation with lambda = 200-800 nm to give the first sighting of CH3M, the simplest organic derivative of Ga(I) and In(I) to be characterized to date . The vibrational properties of the species CH3MH and CH3M are compared wit h those of related molecules and analyzed for the light they shed on the ch aracters of the M-C and M-H bonds.