Reaction of the C,C-dibenzyl-nido-carborane (PhCH2)2C2B4H6(1) with NaH in THF followed by FeCl2forms a red complex, [(PhCH2)2C2B4H4]2FeH2 (2), which on treatment with 02generates a tetrabenzyl tetracarbon carborane, (PhCH2)4C4B8H8(3). Compound 3 is nonfluxional in solution, in contrast to previously studied R4C4B8H8species where R = Me, Et, or n-Pr, and an X-ray diffraction study of 3 disclosed that the C4B8cage is locked into an open-cage geometry as a consequence of severe intramolecular crowding of the benzyl groups. Reaction of 2 with CpCo(CO)2generates [(PhCH2)2C2B4H4]4FeCoCp (4), for which a wedged structure is proposed. Treatment of 1 with Cr(CO)6produces the mono- and dichromium complexes (CO)3Cr(PhCH2)2C2B4H6(5) and (CO)6Cr2(PhCH2)2C2B4H6(6) as moderately air-sensitive solids which were characterized from NMR, IR, and mass spectra and an X-ray crystallographic investigation of 6. Crystal data for 3: Mr507, space group P21/c, Z = 4, a = 10.007 (2) Å, b =22.681 (6) Å, c = 13.692 (2) Å, β= 110.18 (2)°, V = 2917 Á3, R = 0.053 for 3813 reflections having F02> 3σ(F0)2. Crystal data for 6: Mr521, space group Pnam, Z = 4, a = 11.914 (2) Å, b = 6.927 (1) Å, c = 28.729 (6) Å, V = 2371 Å3, R = 0.044 for 1678 reflections having F2°> 3σ(F0)2.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Organic Chemistry
- Inorganic Chemistry