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Disordered sodium alkoxides from powder data: crystal structures of sodium ethoxide, propoxide, butoxide and pentoxide, and some of their solvates
Author(s) -
Beske Maurice,
Cronje Stephanie,
Schmidt Martin U.,
Tapmeyer Lukas
Publication year - 2021
Publication title -
acta crystallographica section b
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.604
H-Index - 33
ISSN - 2052-5206
DOI - 10.1107/s205252062001584x
Subject(s) - alkoxide , sodium ethoxide , sodium , chemistry , alkyl , crystal structure , hydrogen bond , sodium oxide , crystallography , inorganic chemistry , ethanol , molecule , organic chemistry , catalysis , oxide
The crystal structures of sodium ethoxide (sodium ethanolate, NaOEt), sodium n ‐propoxide (sodium n ‐propanolate, NaO n Pr), sodium n ‐butoxide (sodium n ‐butanolate, NaO n Bu) and sodium n ‐pentoxide (sodium n ‐amylate, NaO n Am) were determined from powder X‐ray diffraction data. NaOEt crystallizes in space group P 4 2 1 m , with Z = 2, and the other alkoxides crystallize in P 4/ 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 (NaO n Pr·2 n PrOH), sodium isopropoxide isopropanol pentasolvate (NaO i Pr·5 i PrOH) and sodium tert ‐amylate tert ‐amyl alcohol monosolvate (NaO t Am· t AmOH, t Am = 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 i PrOH network in NaO i Pr·5 i PrOH shows branched hydrogen bonds and differs considerably from the networks in pure crystalline i PrOH.