FIRST X-RAY CRYSTALLOGRAPHIC CHARACTERIZED CS-MEMBERED CORONAND - (MALEONITRILE-DITHIO[21]CROWN-7)CAESIUM HEXACHLOROANTIMONATE( IN CAVITY COMPLEX OF A 21)

A new maleonitrile-crown dithioether, the maleonitrile-dithio[21]crown -7 (mn-21 S2O5), was synthesized by high dilution cyclization of (Z)-1 ,2-disodium-1 2-dicyanoethene-1,2-dithiolate (1) with 1,17-dichloro-3, 6,9,12,15-pentaoxaheptadecane (2) in ethanol/water mixtures. Mn-21 S2O 5 forms with CsSbCl6 in MeCN/MeNO2 a 1:1 complex [Cs(mn-21 S2O5)]SbCl6 . X-ray crystal analysis revealed that the complex cation [Cs(mn-21 S2 O5)](+) is an ''in cavity'' complex in which the Cs+ ion is coordinate d by seven donor atoms (five O and two S atoms). This is the first X-r ay crystallographic evidence of Cs+ coordination by seven donors in a hole of a twenty-one membered coronand.