Synthesis, structure and chemistry of low-boron containing molybdaborane: Arachno-[Cp*Mo(CO)2B3H8].

Room temperature photolysis of [Cp*Mo(CO) 3 Me], 1 with excess of [BH 3 ·THF] led to the isolation of hydrogen-rich arachno -[Cp*Mo(CO) 2 B 3 H 8 ], 2 in good yield. The geometry of arachno - 2 consists of a butterfly core similar to that of 7 skeletal electron pairs tetraborane(10). Further, the metal fragment addition reaction of arachno - 2 with [Fe 2 (CO) 9 ] yielded a nido -[Cp*Mo(CO) 2 B 3 H 6 Fe(CO) 3 ], 3 that plays a pivotal role in bringing a change in the geometry from arachno - 2 to nido - 3 . The reaction of arachno - 2 with [Ru 3 (CO) 12 ], however, yielded known metal carbonyl compound [Cp*Mo(CO) 3 ] 2 , 4 . All the new compounds have been characterized in solution by mass spectrometry, IR, 1 H, 11 B, 13 C NMR spectroscopy and the solid state X-ray structures of 2 and 3 were unequivocally established by X-ray diffraction analysis. Additionally, we have studied the bonding nature of compounds 2 and 3 with the help of density functional theory (DFT) calculations. [ABSTRACT FROM AUTHOR]