Laser-ablated Al, Ca, In, and Tl atoms react with hydrogen cyanide in the presence of excess argon to produce matrix-isolated linear cyanides and isocyanides, MCN and MNC, respectively. Similar To the products of alkaline earth reactions with hydrogen cyanide and unlike the corresponding boron reactions, no products containing hydrogen are formed. Experiments with (HCN)-C-13 generate (MNC)-C-13 shifted 40 cm(-1) from (MNC)-C-12 in the C=N stretching mode, and this isotopic shift is virtually independent of the group 13 element. Similarly, the MCN molecules exhibit a carbon-13 shift of 45 cm(-1), with the isotopic shift approximately the same for each metal. As the mass of M increases, the C=N frequency decreases far MCN and remains nearly constant for MNC. Group 13 reactions with HCN produce significant amounts of MCN, in contrast to the corresponding alkaline earth reactions, For aluminum, this disparity suggests that an insertion mechanism plays at least a partial role in product formation. For tile heavier elements, photolysis behavior indicates that attack on the nitrogen atom is dominant, with MCN produced following rearrangement, of MNC.