Disordered sodium alkoxides from powder data: crystal structures of sodium ethoxide, propoxide, butoxide and pentoxide, and some of their solvates

  • The crystal structures of sodium ethoxide (sodium ethano­late, NaOEt), sodium n-propoxide (sodium n-propano­late, NaOnPr), sodium n-butoxide (sodium n-butano­late, NaOnBu) and sodium n-pentoxide (sodium n-amylate, NaOnAm) were determined from powder X-ray diffraction data. NaOEt crystallizes in space group P421m, with Z = 2, and the other alkoxides crystallize in P4/nmm, with Z = 2. To resolve space-group ambiguities, a Bärnighausen tree was set up, and Rietveld refinements were performed with different models. In all structures, the Na and O atoms form a quadratic net, with the alkyl groups pointing outwards on both sides (anti-PbO type). The alkyl groups are disordered. The disorder becomes even more pronounced with increasing chain length. Recrystallization from the corresponding alcohols yielded four sodium alkoxide solvates: sodium ethoxide ethanol disolvate (NaOEt·2EtOH), sodium n-propoxide n-propanol disolvate (NaOnPr·2nPrOH), sodium isopropoxide iso­propanol pentasolvate (NaOiPr·5iPrOH) and sodium tert-amylate tert-amyl alcohol monosolvate (NaOtAm·tAmOH, tAm = 2-methyl-2-butyl). Their crystal structures were determined by single-crystal X-ray diffraction. All these solvates form chain structures consisting of Na+, –O− and –OH groups, encased by alkyl groups. The hydrogen-bond networks diverge widely among the solvate structures. The hydrogen-bond topology of the iPrOH network in NaOiPr·5iPrOH shows branched hydrogen bonds and differs considerably from the networks in pure crystalline iPrOH.

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Author:Maurice Beske, Stephanie Cronje, Martin U. SchmidtGND, Lukas Tapmeyer
Parent Title (English):Acta crystallographica / Section B
Place of publication:Oxford [u.a.]
Document Type:Article
Date of Publication (online):2021/01/25
Date of first Publication:2021/01/25
Publishing Institution:Universitätsbibliothek Johann Christian Senckenberg
Release Date:2022/03/16
Tag:Bärnighausen tree; PXRD; isopropanol; powder data; sodium alkoxide; solvate
Page Number:15
First Page:68
Last Page:82
Open access funding enabled and organized by Projekt DEAL.
Institutes:Biochemie, Chemie und Pharmazie
Dewey Decimal Classification:5 Naturwissenschaften und Mathematik / 53 Physik / 530 Physik
5 Naturwissenschaften und Mathematik / 54 Chemie / 540 Chemie und zugeordnete Wissenschaften
Licence (German):License LogoCreative Commons - Namensnennung 4.0