Cation-π interactions. Synthesis and crystal structure of complexes [K(B18-C-6)]NCS and [K(DB18-C-6)]2[Hg(SCN)4]

The reactions of benzo-18-crown-6 (B18-C-6) with K 2 [Cd(SCN) 4 ] and dibenzo-18-crown-6 (DB18-C-6) with K 2 [Hg(SCN) 4 ] are reported here. The unexpected complex [K(B18-C-6)]NCS (1) and complex [K(DB18-C-6)] 2 [Hg(SCN)4] (2)have been isolated and characterized by elemental analysis, IR and X-ray diffraction analysis. The complexes belong to monoclinic, space group P2 1 /c and C2/c respectively with cell dimensions, 1: a = 9.960(3), b = 25.097(7), c = 8.374(2) A, β = 106.519(3), V = 2006.7(10) A 3 , Z = 4, D c a l c d . = 1.356 g/cm 3 , F(000) = 864, R 1 = 0.0429, wR 2 = 0.0579 and 2: a = 30.187(17), b = 14.668(8), c = 25.467(15) A, β = 99.517(10), V= 11119(11) A 3 , Z = 8, D c a l c d . = 1.414 g/cm 3 , F(000) = 4752, R 1 = 0.0415, wR 2 = 0.0805. Complex 1 forms one-dimensional infinite chain structure through K + -π interactions between neighboring molecules in the solid state. In complex 2, [K(DB18-C-6)]2[Hg(SCN)4] molecules form a dimeric structure bridged by K + -π interactions between adjacent [K(DB18-C-6)] units.