text: Reactions of yellow arsenic with the group 6 transition metals largely proceed through thermolytic carbon monoxide elimination in chromium and molybdenum carbonyl complexes. Notable examples include the formation of triple-decker complexes [(CpMo)(μ,η-As)] and [{CpCr}(μ,η-As)] via reaction of the corresponding molybdenum and chromium dimers with yellow arsenic. These remarkable structures feature three planar-rings arranged in parallel fashion to result in an idealized D point group for the chromium complex. Both of these reactions necessitate harsh reaction conditions like boiling xylene to overcome the high barriers to activation of As. Conversely, utilization of more sterically demanding ligands on the metal center enabled reactions in milder conditions with molybdenum and chromium. Cummins Mo(N(t'Bu)Ar) catalyst, also known to split the N-N triple bond in dinitrogen, reacts with yellow arsenic to form a terminal arsenic moiety triple-bonded to the metal center - one of only several compounds known to contain a terminal arsenic atom. Complexes with metal-metal multiple bonds also enable mild As activation parameter. A chromium-chromium quintuply-bonded species reported by Kempe reacts with yellow arsenic to form a crown complex in which the four arsenic atoms form an approximately tetrahedral structure, with each chromium atom bonding to three arsenic atoms.