Anions pentacoordi nated

Kanberg and Muetterties (50) have shown by NMR spectroscopy that fluorine substituents always occupy the apical positions in pentacoordi-nated anions such as RSiFj or R3SiFz. Thus, using the rules for phosphorus chemistry, the most stable intermediates will be 12 and 13,... 

The authors suggested a mechanism via the intermediacy of a reactive pentacoordi-nated hydrosilyl anion,50c which is formed by the addition of hydride (H-) on the silanes, for the redistribution reactions. 

In the solid state, a series of anion receptors may assemble in various assembling modes in the forms of receptor-anion complexes by combination with counter cations. jS-Unsubstituted lb afforded a planar [1 -1- l]-type pentacoordi-nated CF complex Ib CF that involved the pyrrole NH, the bridging CH, and phenyl ortho-CH units (Fig. 9.3a). Planar anion Ib CF stacked with tetrapropy-lammonium cations (TPA" ) to form a charge-by-charge columnar structure with a Cl -Cl distance of 8.54 A, and a separation of 7.29 A between the Ib CF units... 

---