Reactions of an Electronically Unsaturated Chromaborane. Coordination of CS 2 to (η 5 -C 5 Me 5 ) 2 Cr 2 B 4 H 8 and Its Hydroboration to a Methanedithiolato Ligand

The reaction of the electronically unsaturated Cp* 2 Cr 2 B 4 H 8 ( 1; Cp* = η 5 -C 5 Me 5 ) cluster with CS 2 yields the saturated Cp* 2 Cr 2 (CH 2 S 2 B 4 H 6 ) ( 3 ) cluster in better than 90% isolated yield. Both solution spectroscopic and solid-state crystallographic data show that 3, with C 2 point symmetry, contains an intracluster bridging methanedithiolato H 2 CS 2 ligand in which the S atoms of the ligand have replaced two transoid BHCr bridging hydrogens in 1, which in turn have added to the carbon atom. The three compounds 1, Cp* 2 Cr 2 (CO) 2 B 4 H 6 ( 2 ), and 3 exhibit similar cluster geometries but possess 42, 44, and 46 cluster valence electrons, respectively.