IR and UV-vis spectroscopic measurements have been used to chart the thermal and photolytic reactions occurring in HCl-doped Ar matrixes containing Zn, Cd, or Hg atoms (M). Following the formation of a loosely bound metal atom adduct M‚‚‚HCl, the primary reaction induced by UV irradiation (200 e λ e 400 nm) is insertion of M into the H-Cl bond to give the molecule HMCl, which has been characterized by its IR spectrum, with assignments validated by the effects of isotopic change ( 1,2 H, 35,37 Cl, and 64,66,68 Zn) and by the results of density functional theory calculations. The properties of HMCl are compared with those of other Group 12 metal hydrides, and the mechanism of insertion is also discussed.

Matrix-isolation experiments give evidence that broad-band UV-vis irradiation (200 e λ e 800 nm) of an Ar matrix doped with SiH 4 and a group 12 metal atom M (M ) Zn, Cd, or Hg) induces metal insertion into an Si-H bond to give the silyl metal hydride molecule HMSiH 3 as the primary product. Si 2 H 6 is a second product, irrespective of the identity of M, while the binary hydride MH 2 is also formed when M ) Zn or Cd. The products have been identified by their IR spectra and experiments with SiD 4 , together with the results of quantum chemical calculations, have provided the means of authentication. The properties of the HMSiH 3 molecules are compared with those of related species, and consideration is given to how the products come to be formed.

IR and UV-vis spectra have been used to chart the thermal and photolytic reactions occurring during or after the codeposition of Ga vapour with an excess of H 2 O-doped Ar. Following the formation of the loosely bound adducts GaÁ Á ÁOH 2 and Ga 2 Á Á ÁOH 2 , detected after deposition of the matrix, UV irradiation (200 r l r 400 nm) causes GaÁ Á ÁOH 2 to rearrange with insertion of the metal atom into an O-H bond forming the Ga(II) hydride HGaOH, while visible irradiation (l ¼ ca. 580 nm) causes Ga 2 Á Á ÁOH 2 to rearrange with the formation of cyclic Ga(m-H)(m-OH)Ga. Broad-band photolysis (200 r l r 800 nm) results in the destruction of both these products, with HGaOH decaying to GaOH. Characterisation of the various molecules by IR spectroscopy has been underpinned by reference (i) to the effects of isotopic change ( 1,2 H, 16,18 O and 69,71 Ga) and (ii) to the results of density functional theory (DFT) calculations. The properties of the molecules are compared with those of related species, and the mechanisms of the photochemical changes are discussed.