Arsaalkynes are produced by dehydrohalogenation or related base-induced elimination reactions. The case of HCAs is illustrative:
Owing to the principles of the double bond rule, arsaalkynes tend to oligomerize more readily than the phosphorus analogues.  Thus attempts to prepare AsCCMe produce the tetramer, which has a cubane structure.  The very bulky substituent CH-2,4,6-(t-Bu) does however allow the crystallization of the monomeric arsaalkyne.  Its As-C bond length is 1.657(7) Å.