. Can. J. Chem. 68, 797 (1990) New macrocycle polyether 18-crown-6 complexes of stoichiometry [(H30+. 1 8 -~r o w n -6 )~(~C l~~-) ] have been synthesized for M = Zn and Mn. The two complexes are isostructural and crystallize in the monoclinic system, space group C2/c. The unit cell dimensions are as follows: a = 16.229(9), b = 11.535(3), c = 20.134(8) A, P = 97.55(4)" and a = 16.255(6), b = 11.625(3), c = 20.122(8) A, P = 96.54(3)" for the Zn and Mn complexes respectively. In both crystal structures (final R,, = 0.048 with 1817 reflections for Zn and R, = 0.074 with 728 reflections for Mn), the crown ether molecule and the H30+ cation to which it is hydrogen-bonded are disordered over two sites. The M C~~~-anions, which have tetrahedral toordination, are on crystallographic twofold axes of rotation. The Mn-Cl and Zn-C1 distances average 2.270 and 2.361 A respectively. The hydronium cation, H30+, has pyramidal coordination. Of the two disordered crown ether molecules in the Zn and the Mn complexes, one has a slightly deformed (ttg)6 conformation while the other one may be described as having the distorted (ttg)5(ttc) conformation. These observations are in agreement with the infrared analyses of the complexes.Key words: 18-crown-6 complexes, hydronium ion, ~n C l~~-, M~c I~~-, crystal structure. pyramidale. Des deux molCcules dlCthers couronnes dtsordonnCes qui sont prksentes dans les complexes du Zn et du Mn, l'une posskde une conformation 1Cgkrement dCformCe (ttg)6 alors que l'on peut dtcrire la conformation dCformCe de l'autre par ( t~)~( t t c ) .Ces observations sont en accord avec les analyses infrarouges de ces complexes. Mots clis : complexes 18-couronne-6, ion hydronium, znC14'-, MnC142-, structure cristalline.[Traduit par la revue]
