Synthesis and crystal structures of complexes between caesium thiocyanate and two isomeric macrocyclic crown polyethers, 6,7,9,10,17,18,20,21-octahydro-7R,9R,18S,20S-tetramethyldibenzo[b,k][1,4,7,10,13,16]hexaoxacyclo-octadecin (isomer F) and 6,7,9,10,17,18,20,21-octahydro-7R,9R,18R,20R-tetramethyldibenzo[b,k][1,4,7,10,13,16]-hexaoxacyclo-octadecin (isomer G)

Abstract

Two isomers, F and G, of tetramethyldibenzo-18-crown-6 each with 4 chiral carbon atoms give complexes with caesium thiocyanate; CsNCS(F) consists of centrosymmetrical dimeric molecules with Cs–N–Cs bridges, the other co-ordinating atoms being the six oxygens of F at 3·07–3·34 Å and the aryl carbon atoms at 3·79 Å, while CsNCS(G)₂ consists of Cs(G)₂⁺ cations having symmetry with 12 Cs–O contacts at 3·17–3·43 Å and disordered thiocyanate ions.