Chemistry of Dimetallaoctaborane(12) with Chalcogen-Based Borate Ligands: Obedient versus Disobedient Clusters

The reactions of dimetallaoctaboranes(12) [(Cp*M) 2 B 6 H 10 ] [M = Co ( 1 ) or Rh ( 2 ); Cp* = η 5 -C 5 Me 5 ] with different chalcogen sources, such as Li[BH 2 E 3 ] and Li[BH 3 EPh] (E = S, Se, or Te), led to two unique reaction outcomes. For example, the formation of 10-vertex nido -[(Cp*M) 2 B 6 E 2 H 6 ] ( 3 , M = Co, E = S; 4 , M = Co, E = Se; 5 , M = Co, E = Te; 6 , M = Rh, E = Se) from compounds 1 and 2 is a typical representation of a cluster growth reaction, while the formation of arachno -[(Cp*Co) 2 B 6 H 9 (EPh)] [E = S ( 9 ), Se ( 10 ), or Te ( 11 )] is a rare method that yielded arachno clusters, keeping the core geometry identical. The formation of arachno - 9 - 11 is a unique method that converts disobedient cluster 1 o obedient clusters 9 - 11 . Further, the reactivity of nido - 4 with various metal carbonyls presented sequential cluster growth reactions, which afforded 11-vertex nido -[(Cp*Co) 2 B 6 Se 2 H 6 {Fe(CO) 3 }] ( 7 ) and 13-vertex fused closo -[(Cp*Co) 2 B 6 Se 2 H 6 {Ru 3 (CO) 8 }] ( 8 ). The core geometry of nido - 7 is uncommon and very similar to that of [C 2 B 9 H 11 ] 2- with a unique open pentahapto-coordinating five-membered face.