Partial incorporation of a cyclopentadienyl ligand into a molybdaborane to form a molybdacarbaborane

Reaction of the molybdaborane arachno -2-[Mo(η-C5H5)(η5:η1-C5H4)B4H7] (I) with NEt3 in toluene at 120 °C for 7 days gives a 90% yield of the molybdacarbaborane nido -1-[Mo(η-C5H5)(η3:η2-C3H3)C2B3H5] (II). Two of the carbon atoms in the substituted cyclopentadienyl ring in I are incorporated into the metallacarbaborane cluster II. The carbaborane {C2B3H5} fragment in II is attached to an allylic {C3H3} group and can be thought of as a new non-planar {C5B3H8} ligand providing seven electrons to the molybdenum atom. Reaction of I with KH in thf at 20 °C gives the anion View the MathML source[nido-1-Mo(η-C5H5)(η3:η2-C3H3)C2B3H4-](III) via deprotonation of a B–H–B bridging proton.