SYNTHESIS AND BONDING IN HYBRID DIBOROLYL BORANYL AND THIABORANYL TRIPLE-DECKER COMPOUNDS - ELECTRONIC CONTRIBUTION OF HETEROBORANE CLUSTERLIGANDS IN COMPLEXES/

The three-component reaction of [(eta(5)-C5H5)Co{eta(5)-(CEt)(2)(BEt)( 2)CMe}](-) (6-H)(-), CoCl2 and B9H14- (7) yields the triple-decker com plex 5H5)Co{mu,eta(5)-(CEt)(2)(BEt)(2)CMe}-6-Co(B9H13)] (8) with a ter minal B9H13 ligand containing two cobalt-boron-bridging hydrogen atoms . Analogously, (6-H)(-), CoCl2, and arachno-6-SB9H12- (10) react to gi ve the triple-decker )Co{mu,eta(5)-(CEt)(2)(BEt)(2)CMe}-1-Co-2-(SB9H9) ] (11). The analogous reaction with the heteroboranyl anion arachno-6, 8-S2B7H8- leads to the loss of one boron atom, forming the air-stable triple-decker complex {mu,eta(5)-(CEt)(2)(BEt)(2)CMe}-7-Co-6,8-(S2B6H8 )] (12). The X-ray structure determination shows that the dithiacobalt aborane fragment in 12 has an arachno cluster geometry. The three-comp onent reaction of (6-H)(-), CoCl2, and arachno-2,3-S2B9H10- yields the expected triple-decker 5H5)Co{mu,eta(5)-(CEt)(2)(BEt)CMe}Co-6,8-(S2B9 H9)] (15), and surprisingly the sandwich complex (eta(5)-C5H5)Co-6,8-( S2B9H9) (16). The constitutions of the new compounds are based on NMR and MS data. A rule is described regarding the electron donation of he teroboranyl cluster ligands in metal complexes.