Multinuclear silver ethynide supramolecular synthons for the construction of coordination networks

The invariant appearance of the mu(s) coordination mode for the C-4(2-) dianion in its silver(I) complexes, with four silver(I) atoms attached to each terminal ethynide moiety, implies that the Ag-4 subset of C equivalent to C=-C-C equivalent to C superset of Ag-4 species may be considered as a new type of supramolecular synthon for the construction of 1D, 2D, and 3D coordination polymers. This Focus Review covers recent results on the synthesis and structural characterization of silver(I) aryl-ethynide and alkylethynide complexes, which established the existence and utility of analogous polynuclear supramolecular synthons R-C equivalent to C superset of Ag-n (R = aryl or alkyl; n = 4, 5) and Ag-n subset of C-2-R-C-2 superset of Ag-n (R = p-, m-, o-C6H4; n = 4, 5). The interplay of silver-ethynide bonding, which can be classified into sigma, pi, and mixed (sigma,pi) types, with argentophilicity, pi-pi stacking, and other weak interactions highlights the complexity and challenge in building coordination networks of silver ethynide complexes.