REACTIONS OF LASER-ABLATED MG, CA, SR, AND BA ATOMS WITH HYDROGEN-CYANIDE IN EXCESS ARGON - MATRIX INFRARED-SPECTRA AND DENSITY-FUNCTIONAL CALCULATIONS ON NOVEL ISOCYANIDE PRODUCTS

Laser-ablated alkaline earth metal atoms reacting with hydrogen cyanid e in the presence of excess argon produce matrix-isolated linear metal isocyanides, MNC, but no noticeable amount of the corresponding cyani de isomer, MCN. Supplemental experiments with DCN show that, unlike th e corresponding beryllium reactions, no products containing hydrogen a re formed. Experiments with isotopically enriched (HCN)-C-13 yield (MN C)-C-13 shifted 40 cm(-1) from (MNC)-C-12 in the C=N stretching freque ncy, with the isotopic shift virtually independent of the alkaline ear th metal. As the mass of the group 2 metal increases, the C=N frequenc y decreases and the absorption becomes broader, the latter feature ind icating a decreasingly rigid linear geometry. The lack of MCN indicate s that the products form via attack of the energetic metal on the nitr ogen atom, instead of through insertion into the C-H bond.