Heterobimetallic Metallaborane Chemistry: Synthesis and Characterization of a “Lightly Stabilized” Molybdairidahexaborane, [{Cp*Ir}{(CO)₃(THF)Mo}B₄H₈], and Its Direct Conversion to [{Cp*Ir}{(CO)₃(L)Mo}B₄H₈] (L = CO, PPh₃, NCPh, CNBu, NH₃, PPh₃CHC(O)OMe)

The reaction of [Cp*IrB4H10] (1) with [{η6-(C6H4)(CH3)2}Mo(CO)3] in tetrahydrofuran (THF) leads to [Cp*Ir(CO)3(THF)MoB4H8] (2), which was characterized by NMR spectroscopy. Intermediate 2 subsequently decomposes to give the tetracarbonyl analogue [Cp*Ir(CO)4MoB4H8] (3). In the presence of free CO, the same reaction constitutes a high-yield synthesis of 3. The treatment of 2 (formed in situ) with different Lewis bases led to the replacement of the THF ligand at the molybdenum center and generation of [Cp*Ir(CO)3(L)MoB4H8] (L = PPh3 (4), NCPh (5), CNBu (6), NH3 (7)). Reaction of the benzonitrile derivative 5 with PPh3CHCO2Me afforded the ylide compound [Cp*Ir(CO)3(PPh3CHCO2Me)MoB4H8] (8). All compounds have been spectroscopically characterized, and 3 and 5−7 have been structurally characterized in the solid state. This work demonstrates that, similarly to metal clusters, metallaboranes with labile metal ligands can serve as versatile synthons.