title: A homologous series of regioselectively tetradeprotonated group 8 metallocenes: new inverse crown ring compounds synthesized via a mixed sodium-magnesium tris(diisopropylamide) synergic base.
abstract: Subjecting ferrocene, ruthenocene, or osmocene to the synergic amide base sodium-magnesium tris(diisopropylamido) affords a unique homologous series of metallocene derivatives of general formula [(M(C(5)H(3))(2))Na(4)Mg(4)(i-Pr(2)N)(8)] (where M = Fe (1), Ru (2), or Os (3)). X-ray crystallographic studies of 1-3 reveal a common molecular "inverse crown" structure comprising a 16-membered [(NaNMgN)(4)](4+) "host" ring and a metallocenetetraide [M(C(5)H(3))(2)](4-) "guest" core, the cleaved protons of which are lost selectively from the 1, 1', 3, and 3'-positions. Variable-temperature NMR spectroscopic studies indicate that 1, 2, and 3 each exist as two distinct interconverting conformers in arene solution, the rates of exchange of which have been calculated using coalescence and EXSY NMR measurements.
authors.affiliation: Contribution from the Department of Pure and Applied Chemistry, University of Strathclyde, Glasgow G1 1XL, Scotland, U.K.
authors.forename: Prokopis C
authors.initials: PC
authors.lastname: Andrikopoulos
authors.forename: David R
authors.initials: DR
authors.lastname: Armstrong
authors.forename: William
authors.initials: W
authors.lastname: Clegg
authors.forename: Carly J
authors.initials: CJ
authors.lastname: Gilfillan
authors.forename: Eva
authors.initials: E
authors.lastname: Hevia
authors.forename: Alan R
authors.initials: AR
authors.lastname: Kennedy
authors.forename: Robert E
authors.initials: RE
authors.lastname: Mulvey
authors.forename: Charles T
authors.initials: CT
authors.lastname: O'Hara
authors.forename: John A
authors.initials: JA
authors.lastname: Parkinson
authors.forename: Duncan M
authors.initials: DM
authors.lastname: Tooke