Synthesis and crystal structures of Ag and Hg complexes of bis( N -heterocyclic carbenes) on p - tert -butylcalix[4]arene platform.

A series ofp-tert-butylcalix[4]arene 1,3-diimidazolium salts were successfully prepared by the alkylation ofp-tert-butylcalix[4]arene with dibromoalkanes, and sequential substitution reaction with 1-alkylimidazole. Furthermore, coordination reactions ofp-tert-butylcalix[4]arene 1,3-diimidazolium salts with silver oxide and mercury acetate gave novel Ag and Hg complexes of bis(N-heterocyclic carbenes) onp-tert-butylcalix[4]arene platform. The single-crystal structures of fourp-tert-butylcalix[4]arene 1,3-diimidazolium salts and three metal complexes were successfully determined by X-ray diffraction. An Ag–Ag argentophilic interaction (Ag–Ag bond length is 3.1599(6) Å) is formed between the two Ag–NHC complexes and a dimetallic coordination mode exists in Hg–NHC complexes. [ABSTRACT FROM PUBLISHER]