Crystalline complexes of 18-crown-6 with methyl sulfonates

Abstract

The macrocyclic polyether 18-crown-6 forms crystalline complexes with methyl sulfonates. Most complexes have a 2:1 (sulfonate:crown) stoichiometry whereas small aliphatic sulfonates give a 1:1 ratio. In the 2:1 ratio complexes, the guest molecules are coordinated above and below the crown in such a way that the dipoles are compensated. In the 1:1 ratio complexes, there is a polymeric type association with the two ends of the sulfonate interacting with different crown molecules. A crystal structure is reported for each type of complex. The complex 18-crown-6•CH3SO3CH3 (7) crystallizes in the monoclinic system, space group P21/c with Z = 4. The unit cell dimensions are as follows: a = 8.525(4), b = 16.401(7), c = 15.071(6) Å, β = 113.92(3)°. Final Rw = 0.064 for 3650 reflections. The complex 18-crown 6•(C6H5SO3Me)2 (1) crystallizes in the monoclinic system, space group P21/c with Z = 2. The unit cell dimensions are as follows: a = 8.101(3), b = 17.136(5), c = 12.990(5) Å, β = 121.30(3)°. Final Rw = 0.048 for 2913 reflections.