Complexation of cyclic trimeric perfluoro-o-phenylenemercury with nitriles.: A remarkable sensitivity of the composition and structure of the resulting complexes to the nature of a nitrile

Cyclic trimeric perfluoro-o-phenylenemercury (o-C6F4Hg)(3) (I) is capable of reacting with nitriles to form complexes whose composition and structure are dramatically dependent on the nature of the nitrile used. In the case of acrylonitrile, the complex, [(o -C6F4Hg)(3)(CH2CHCN)], containing one nitrile molecule per one molecule of I is produced. According to an X-ray structure analysis, the acrylonitrile ligand in this complex is bonded to all Hg atoms of the cycle through the nitrogen atom. The reaction of I with acetonitrile gives complex [(o-C6F4Hg)(3)(MeCN)(2)] which contains two nitrile ligand per one molecule of the macrocycle. This complex has a shape of a spinning top the equatorial girdle of which is the mercury-containing metallacycle, whilst the axis direction is fixed by the linear MeCN ligands located above and below the metallacycle plane. Finally, the isolated complex of I with benzonitrile, [(o-C6F4Hg)(3)(PhCN)(3)], contains three molecules of the coordinated nitrile per one macrocycle molecule. A remarkable structural feature of this complex is that here all the nitrile ligands are located on one side of the metallacycle plane and, in addition, differ from each other in the geometry of coordination with the Hg atoms. (C) 2000 Elsevier Science S.A. All rights reserved.