1The term `silver-ethynide' is preferred to `silver-ethynyl' because the silver-carbon bonding interaction is considered to be mainly ionic with minor covalent [sigma] and [pi] components; the negative charge residing mainly on the terminal C atom draws neighbouring AgI atoms close to one another to facilitate the onset of argentophilic Ag...Ag interactions.

2Supporting information for this paper is available from the IUCr electronic archives (Reference: BI5014 ).