Synthesis and structures of 15- and 18-membered unsaturated selenacrown ethers and their complexation with silver trifluoroacetate

The reaction of Na(2)Se with cis-dichloroethene yielded (Z,Z,Z,Z,Z)-1,4,7,10,13-pentaselenacyclopentadeca-2,5,8,11,14-pentaene (15-US-5) and (Z,Z,Z,Z,Z,Z)-1,4,7,10,13,16-hexaselenacyclooctadeca-2,5,8,11,14,17-hexaene (18-US-6). X-ray crystallographic analysis of 15-US-5 and 18-US-6 revealed an all-cis geometry around the carbon-carbon double bonds, with all of the selenium atoms located on one side of the respective ring planes. 15-US-5 and 18-US-6 were also found to be oxidized more easily than the corresponding sulfur analogues. The complexation of 15-US-5 and 18-US-6 with silver trifluoroacetate afforded Ag(I)(15-US-5)(CF(3)COO) and Ag(I)(5)(18-US-6)(3)(CF(3)COO)(5), respectively. reaction: see text]