title: New supramolecular assemblies in heterobimetallic chemistry: synthesis of a homologous series of unsolvated alkali-metal zincates.
abstract: Using an interlocking co-complexation approach, a homologous series of unsolvated alkali-metal zincates [MZn(CH2SiMe3)3] (M = Li 1, Na 2, K 3) was prepared by reacting equimolar amounts of Zn(CH2SiMe3)2 with the relevant alkali-metal alkyl M(CH2SiMe3) employing non-coordinating hexane as a solvent. X-ray crystallographic studies reveal that these heterobimetallic compounds exhibit unprecedented supramolecular assemblies made up exclusively of a three-fold combination of M-CH2, Zn-CH2 and M···Me interactions. Revealing an important alkali-metal effect, 1 displays a linear chain structure; whereas 2 and 3 form much more intricate 3D and 2D coordination networks respectively. Shedding new light into the formation of these solvent-free zincates, DFT calculations indicate that the infinite degree of aggregation observed in 1-3 plays a major role in thermodynamically driving the co-complexation reactions of their homometallic precursors. NMR spectroscopic studies suggest that in C6D6 solution 1-3 exist as discrete contacted ion-pair species, where the alkali-metal is partially solvated by molecules of deuterated solvent. The supramolecular assemblies of 1-3 can be easily deaggregated by adding the polydentate N-donors PMDETA (N,N,N',N'',N''-pentamethyldiethylenetriamine) or TMEDA (N,N,N',N'-tetramethylethylenediamine), affording monomeric [(PMDETA)LiZn(CH2SiMe3)3] (4) and [(TMEDA)2NaZn(CH2SiMe3)3] (5).
authors.affiliation: WestCHEM, Department of Pure and Applied Chemistry, University of Strathclyde, Glasgow, G11XL, UK. eva.hevia@strath.ac.uk.
authors.forename: David R
authors.initials: DR
authors.lastname: Armstrong
authors.forename: Helena S
authors.initials: HS
authors.lastname: Emerson
authors.forename: Alberto
authors.initials: A
authors.lastname: Hernán-Gómez
authors.forename: Alan R
authors.initials: AR
authors.lastname: Kennedy
authors.forename: Eva
authors.initials: E
authors.lastname: Hevia