105472-93-3Relevant academic research and scientific papers
Organotransition-metal metallacarboranes. 11. Chromium tricarbonyl η6-complexes of nido-2,3-(PhCH2)2C2B4H6: Metal complexation and oxidative fusion
Whelan, Thomas,Spencer, James T.,Pourian, Mohammad R.,Grimes, Russell N.
, p. 3116 - 3119 (2008/10/08)
The consequences of η6-phenyl coordination of Cr(CO)3 groups on the chemistry of the C,C′-dibenzylcarborane nido-2,3-(PhCH2)2C2B4H6 (1) were investigated. The monochromium species [(CO)3Cr](PhCH2)2C2B 4H6 (2) underwent bridge (B-H-B) deprotonation by NaH in THF, and the resulting anion, on treatment with FeCl2, formed [[(CO)3Cr](PhCH2)2C2B 4H4]2FeH2 (not isolated); subsequent oxidation with O2 gave two isomers of [(CO)3Cr]2(PhCH2)4C 4B8H8 (7A,B), which were characterized spectroscopically. Reaction of the tetracarbon carborane (PhCH2)4C4B8H8 (5) with Cr(CO)6 gave dichromium products identical with 7A,B but no other isomers. An attempted analogous sequence with [(CO)3Cr]2(PhCH2)2C 2B4H6 (3) proceeded only as far as bridge deprotonation with KH; the resulting anion on treatment with FeCl2/O2 did not undergo fusion, nor was fusion observed with other transition metals. An attempted mixed-ligand fusion of the anions of 1 and 3 gave only 5 and the original substrate 3. Deprotonation of 3 was shown to proceed cleanly, via deuteriation of the anion to produce monodeuteriated 3. The resistance of 3 to oxidative fusion is discussed in terms of steric and electronic effects.
Organotransition-metal metallacarboranes. 10. π-Complexation of nido-(PhCH2)2C2B4H6 at the C2B3 and C6 Rings. Synthesis and crystal structures of nido-2,3-[(CO)3Cr(η6-C6H 5)CH2]2-2,3-C2B4H ...
Spencer, James T.,Pourian, Mohammad R.,Butcher, Ray J.,Sinn, Ekk,Grimes, Russell N.
, p. 335 - 343 (2008/10/08)
Full title: Organotransition-metal metallacarboranes. 10. π-Complexation of nido-(PhCH2)2C2B4H6 at the C2B3 and C6 Rings. Synthesis and crystal structures of nido-2,3-[(CO)3Cr(η6-C6H 5)CH2]2-2,3-C2B4H 6 and (PhCH2)4C4B8H8, a nonfluxional C4B8 cluster. Reaction of the C,C′-dibenzyl-nido-carborane (PhCH2)2C2B4H6 (1) with NaH in THF followed by FeCl2 forms a red complex, [(PhCH2)2C2B4H4] 2FeH2 (2), which on treatment with O2 generates a tetrabenzyl tetracarbon carborane, (PhCH2)4C4B8H8 (3). Compound 3 is nonfluxional in solution, in contrast to previously studied R4C4B8H8 species where R = Me, Et, or n-Pr, and an X-ray diffraction study of 3 disclosed that the C4B8 cage is locked into an open-cage geometry as a consequence of severe intramolecular crowding of the benzyl groups. Reaction of 2 with CpCo(CO)2 generates [(PhCH2)2C2B4H4] 4FeCoCp (4), for which a wedged structure is proposed. Treatment of 1 with Cr(CO)6 produces the mono- and dichromium complexes (CO)3Cr(PhCH2)2C2B4H 6 (5) and (CO)6Cr2(PhCH2)2C2B 4H6 (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: Mr 507, space group P21/c, Z = 4, a = 10.007 (2) A?, b = 22.681 (6) A?, c = 13.692 (2) A?, β = 110.18 (2)°, V = 2917 A?3, R = 0.053 for 3813 reflections having Fo2 > 3σ(Fo)2. Crystal data for 6: Mr 521, space group Pnam, Z = 4, a = 11.914 (2) A?, b = 6.927 (1) A?, c = 28.729 (6) A?, V = 2371 A?3, R = 0.044 for 1678 reflections having Fo2 > 3σ(Fo)2.
