The consequences of η6-phenyl coordination of Cr(CO)3groups on the chemistry of the C,C-dibenzylcarborane nido-2,3-(PhCH2)2C2B4H6(1) were investigated. The monochromium species [(CO)3Cr](PhCH2)2C2B4H6(2) underwent bridge (B-H-B) deprotonation by NaH in THF, and the resulting anion, on treatment with FeCl2, formed [[(CO)3Cr](PhCH2)2C2B4FI4]2FeH2(not isolated); subsequent oxidation with 02gave two isomers of [(CO)3Cr]2(PhCH2)4C4B8H8(7A,B), which were characterized spectroscopically. Reaction of the tetracarbon carborane (PhCH2)4C4BgH8(5) with Cr(CO)6gave dichromium products identical with 7A,B but no other isomers. An attempted analogous sequence with [(CO)3Cr]2(PhCH2)2C2B4H6(3) proceeded only as far as bridge deprotonation with KH; the resulting anion on treatment with FeCl2/O2did 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.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry