Crystal structures of "supramolecular" benzo-18-crown-6 potassium tetrathiocyanato metallates: A dimeric complex {[K(Benzo-18-crown-6)](2)[Hg(SCN)(4)]}(2) and two isomeric complexes [K(Benzo-18-crown-6)][Cd(SCN)(3)] containing trithiocyanato cadmate anions with chain structures

By reaction of potassium thiocyanatomercurate(II) complexes with benzo-18-c rown-6 (2,3-benzo-1,4,7,10,13,16-hexaoxacyclooctadec-2-ene) crystals of {[K (benzo-18-crown-6)](2)[Hg(SCN4)]}(2) (1) were obtained. 1 crystallizes mono clinic, space group P2(1)/n (non-standard setting of P2(1)/c), a = 1737.35( 2), b = 1377.16(2), c =1984.12(3) pm, beta= 100.637(1)degrees Z=2. With pot assium tetrathiocyanatocadmate(II) two modifications of a complex [K(benzo- 18-crown-6)][Cd(SCN)(3)] (2, 3), of different symmetry were formed. 2 cryst allizes monoclinic, P21/c, a=1158,31(3), b=1096,55(2), c=2028,46(2)pm, beta =99,5261(2)degrees, Z=4, 3 orthorhombic, P2(1)cn, a=1105,95(3), b=1413,07(4 ), c=1617,10(5)pm, Z=4. 1 has a dimeric structure, built up from a dication K-2(benzo-18-crown-6)(2)](2+) and two [K(benzo-18-crown-6)If cations, whic h are bridged by two [Hg(SCN)(4)](2-) anions. In 2 and 3 triply bridged inf inite [{Cd(SCN)(3)(-)}(n)] zigzag chains, stretching along screw axes, are to be found as anions. In 2 these chains exist in two conformations related by inversion symmetry, whereas in 3 only one form can be found. [K(benzo-1 8-crown-6)](+) cations are linked to the anion chains via K ... S interacti ons of different lengths.