BI-CO HETERONUCLEAR CARBONYL-COMPOUNDS - SYNTHESIS OF THE ANION [BI(CO(CO)4)4]- AND X-RAY CRYSTAL-STRUCTURE OF ITS TETRAMETHYLAMMONIUM SALT

The anion [Bi{Co(CO)4}4]- has been obtained either by reaction of BiCl3 with the anion [Co(CO)4]-, in a 1 4 molar ratio and also by treating the preformed neutral [Bi{Co(CO)4}3] with [Co(CO)4]- in a 1 1 molar ratio. The salt [NMe4][Bi{Co(CO)4}4] crystallizes in the monoclinic space group P21/c (No. 14) with a 12.327(3), b 14.181(3), c 19.017(4) Å, β 106.14(2) °, Z = 4. The structure was solved by the conventional Patterson and Fourier methods and refined, by use of 2201 significant unique reflections, to a final R value of 0.035. The anion contains a central Bi atom bound with a tetrahedral geometry to four Co(CO)4 units. The four BiCo bonds are very long (mean 2.914 Å) owing to the presence on the Bi atom of an extra electron pair. Each cobalt atom exhibits a distorted trigonal bipyramidal coordination, with the three-fold axis coincident with the BiCo direction. © 1988.