title: Pentacoordinate cobalt(III) thiolate and nitrosyl tropocoronand compounds.
abstract: 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 pi-interaction between the metal and NO pi* orbitals. In the presence of excess NO, [Co(TC-4,4)] exhibited novel reactivity in which a putative Co(N2) adduct formed.
authors.affiliation: Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
authors.forename: K J
authors.initials: KJ
authors.lastname: Franz
authors.forename: L H
authors.initials: LH
authors.lastname: Doerrer
authors.forename: B
authors.initials: B
authors.lastname: Spingler
authors.forename: S J
authors.initials: SJ
authors.lastname: Lippard