STABILIZING ROLE OF INCLUDED SOLVENT IN TERNARY COMPLEXATION - SYNTHESIS, STRUCTURES AND THERMAL ANALYSES OF 3 18-CROWN-6 SULFONAMIDE ACETONITRILE INCLUSION-COMPOUNDS

The synthesis, thermal analyses and X-ray crystal structures of three ternary inclusion compounds, each containing 1,4,7,10,13,16-hexaoxacyclooctadecane (18-crown-6), ethanenitrile (acetonitrile) and a sulfonamide, in different molar ratios, are reported. The compounds are: (I) 1,4,7,10,13,16-hexaoxacyclooctadecane-4-amino-N-(5-methoxy-2-pyrimidinyl) benzenesulfonamide-ethanenitrile (1/2/4), C42H60N12O12S2, M(r) = 989.13, I2/c, a = 16.304 (6), b = 20.321 (8), c= 15.939 (6) angstrom, beta = 102.25 (2)degrees, V = 5161 (3) angstrom3, Z = 4, D(x) = 1.273 g cm-3, lambda(Mo Kalpha) = 0.7107 angstrom, mu = 1.63 cm-1, F(000) = 2096, R = 0.051 for 3446 unique reflections. (II) 1,4,7,10,13,16-hexaoxacyclooctadecane 4-amino-N-2-thiazolylbenzenesulfonamide ethanenitrile (1/1/1), C23H36N4O8S2, M(r) = 560.68, P2(1)/n, a = 8.355 (4), b = 40.104 (4), c = 9.339 (2) angstrom, beta = 111.13 (3)degrees, V = 2919 (2) angstrom3, Z = 4, D(x) = 1.276 g cm-3, lambda(Mo Kalpha) = 0.7107 angstrom, mu = 2.21 cm-1, F(000) 1192, R = 0.041 for 4236 unique reflections. (III) 1,4,7,10,13,16-hexaoxacyclooctadecane-4-amino-N-(4-methyl-2-pyrimidinyl) benzenesulfonamide-ethane-nitrile (1/2/2), C38H54N10O10S2, M(r) = 875.03, P2(1)/c, a = 13.558 (3), b = 14.570 (3), c = 11.404 (1) angstrom, beta = 95.38 (1)degrees, V = 2243 (1) angstrom3, Z = 2, D(x) = 1.296 g cm-3, lambda(Mo Kalpha) = 0.7107 angstrom, mu = 1.74 cm-1, F(000) = 928, R = 0.047 for 3234 unique reflections. These compounds show analogous behaviour on heating. Differential scanning calorimetric traces recorded in the range 300-500 K indicate loss of CH3CN as the first step, followed by recrystallization of the resulting binary crown ether-sulfonamide complex and finally, melting of the latter with decomposition. X-ray analysis reveals distinctly different modes of CH3CN inclusion. In (I), CH3CN molecules engage in cavitate binding (C-H...O) to the host crown ether as well as clathrate binding, occupying channels in the crystal. The sulfonamide is not directly associated with the host. In (II), the host displays face differentiation, with CH3CN ligated (C-H...O) to one face and the sulfonamide ligated (N-H...O, C-H...O) to the other face. The CH3CN molecules in (III) occupy channels only, while the amino groups of two inversion-related sulfonamide molecules are hydrogen bonded (N-H...O) to opposite faces of the crown ether.