Coordination chemistry of polymercuramacrocycles. Complexation of cyclic trimeric perfluoro-o-phenylenemercury with neutral oxygeneous Lewis bases

Cyclic trimeric perfluoro-o-phenylenemercury (o-C6F4Hg)3 (I) readily reacts with N,N-dimethylformamide and hexamethylphosphoramide to form complexes {[(o-C6F4Hg)3](HCONMe2)2} (II) and {[(o-C6F4Hg)3][(Me2N)3PO]2} (III), respectively, which contain two amide ligands per one macrocycle molecule. An X-ray diffraction study of II and III has shown that they have bipyramidal structures wherein the molecules of an amide are located above and below the metallacycle plane and each of them is simultaneously bonded via the oxygen atom to all Hg atoms of the cycle. The reaction of I with dimethylsulfoxide affords complex {[(o-C6F4Hg)3](Me2SO)3} (VI) containing three Lewis basic species per molecule of I. According to X-ray diffraction data, two of three dimethylsulfoxide ligands in VI are also coordinated through the oxygen atom with all mercury centres of the macrocycle, forming a bipyramidal structure, while the third sulfoxide ligand is bonded only to one Hg atom of the cycle. The complex of similar composition and structure, {[(o-C6F4Hg)3](MeCOOEt)3} (IV), is produced in the interaction of I with ethyl acetate but this complex is much less stable than VI. The latter correlates with a considerably lower Lewis basicity of ethyl acetate as compared to that of dimethylsulfoxide.