Organotransition-Metal Metallacarboranes. 41. Synthesis and Structure of B—B- and Cp*—Cp*-Linked Cobaltacarborane Clusters

Xiaotai Wang, Michal Sabat, Russell N. Grimes*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

32 Citations (Scopus)


In an application of Wurtz-type coupling reactions to metallacarborane chemistry, treatment of the B(5)-halogenated closo complexes Cp*Co(2,3-Et2C2B4H3-5-X) (X = Cl, Br, I; Cp* = η5-C5Me5) with sodium metal in THF gave a single red-orange, air-stable product in 20-34% isolated yield. This species was characterized via NMR, UV-visible, and mass spectroscopy and X-ray crystallography as a B—B-linked dimer, 5,5'-[Cp*Co(Et2C2B4H3)]2 (2). Reactions of the same halogenated monomers, as well as the parent complex (X = H), with alkyllithium reagents in THF generated in 28-56% yield the orange, air-stable dimeric products [(-CH2C5Me4)Co(Et2C2B4H3-5-X)]2(3a-d; X = H, Cl, Br, I), which are linked via Cp*-Cp* connections. This geometry, apparently novel to metallacarborane chemistry, was established by an X-ray diffraction study on 3c and supported by spectroscopic data for the four species. Decapitation of these dimers in wet TMEDA gave in high yield the corresponding nido complexes [(-CH2C5Me4)Co(Et2C2B3H4-5-X)]2(4a-d; X = H, Cl, Br, I) as air-stable yellow solids. In contrast, 2 was unaffected by similar treatment. The reaction of nido-Cp*Co(Et2C2B3H4-5-Cl) with sodium in THF gave the yellow air-stable dimeric species [Cp*Co(Et2C2B3H4)]2 (8) together with the unsubstituted monomer Cp*Co(Et2C2B3H5), a previously characterized complex. An X-ray crystal structure determination on 8 disclosed that the two CoC2B3Units are connected via a B-B-B three-center bond such that the two C2B3 rings are almost mutually perpendicular.

Original languageEnglish
Pages (from-to)4668-4675
Number of pages8
Issue number10
Publication statusPublished - Oct 1995
Externally publishedYes


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