Pentacoordinate Cobalt(III) Thiolate and Nitrosyl Tropocoronand Compounds

• Published in: Inorganic chemistry Vol. 40; no. 15; pp. 3774 - 3780
• Main Authors: Franz, Katherine J, Doerrer, Linda H, Spingler, Bernhard, Lippard, Stephen J
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 16-07-2001
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/ic010181l

Reaction of [Co(TC-n,m)]+ with (Me4N)(SC6F5), where (TC-n,m) is a tropocoronand with n and m linker chain methylene groups, yielded the thiolate complexes [Co(SC6F5)(TC-3,3)] (1a), and [Co(SC6F5)(TC-4,4)] (2a), which were structurally characterized. Use of more electron-releasing thiolates afforded the [Co(TC-n,m)] reduction product and the corresponding disulfide. The bent nitrosyl complexes [Co(NO)(TC-3,3)] (1b) and [Co(NO)(TC-4,4)] (2b) were synthesized from [Co(TC-n,m)] and NO and their structures were also determined. Compounds 1a and 1b have square-pyramidal geometry like all other structurally characterized [MX(TC-3,3)] complexes. Compounds 2a and 2b have trigonal-bipyramidal stereochemistry, formerly rare for Co(III). Although 1a, 1b, and 2a are paramagnetic, 2b is diamagnetic due to the strong antibonding π-interaction between the metal and NO π* orbitals. In the presence of excess NO, [Co(TC-4,4)] exhibited novel reactivity in which a putative Co(N2) adduct formed.