Backbone-substituted ß-ketoimines and ketoiminate clusters: transoid Li2O2 squares and D2-symmetric Li4O4 cubanes. Synthesis, crystallography and DFT calculations

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dc.contributor.authorGietz, Twyla M.
dc.contributor.authorBoeré, René T.
dc.date.accessioned2019-04-25T18:29:54Z
dc.date.available2019-04-25T18:29:54Z
dc.date.issued2017
dc.descriptionSherpa Romeo green journal. Open access article. Creative Commons Attribution License (CC BY) applies.en_US
dc.description.abstractThe preparation and crystal structures of four β-ketoimines with bulky aryl nitrogen substituents (2,6-diisopropylphenyl and 2,4,6-trimethylphenyl) and varying degrees of backbone methyl substitution are reported. Backbone substitution “pinches” the chelate ring. Deprotonation with n-butyllithium leads to dimeric Li2O2 clusters, as primary laddered units, with an open transoid geometry as shown by crystal structures of three examples. The coordination sphere of each lithium is completed by one tetrahydrofuran ligand. NMR spectra undertaken in either C6D6 or 1:1 C6D6/d8-THF show free THF in solution and the chemical shifts of ligand methyl groups experience significant ring-shielding which can only occur from aryl rings on adjacent ligands. Both features point to conversion to higher-order aggregates when the THF concentration is reduced. Recrystallization of the materials from hydrocarbon solutions results in secondary laddering as tetramericLi4O4 clusters with a cuboidal core, three examples of which have been crystallographically characterised. These clusters are relatively insoluble and melt up to 250 ◦C; a consideration of the solid-state structures indicates that the clusters with 2,6-diisopropylphenyl substituents form very uniform ball-like molecular structures that will only be weakly solvated.en_US
dc.description.peer-reviewYesen_US
dc.identifier.citationGietz, T., & Boeré, R. T. (2017). Backbone-substituted ß-ketoimines and ketoiminate clusters: transoid Li2O2 squares and D2-symmetric Li4O4 cubanes. Synthesis, crystallography and DFT calculations. Inorganics, 5(2), 30. doi: 10.3390/inorganics5020030en_US
dc.identifier.urihttps://hdl.handle.net/10133/5342
dc.language.isoen_USen_US
dc.publisherMDPIen_US
dc.publisher.departmentDepartment of Chemistry and Biochemistryen_US
dc.publisher.facultyArts and Scienceen_US
dc.publisher.institutionUniversity of Lethbridgeen_US
dc.publisher.urlhttps://doi.org/10.3390/inorganics5020030
dc.subjectβ-ketoimineen_US
dc.subjectβ-ketoiminateen_US
dc.subjectLithiationen_US
dc.subjectHigh-nuclearity clustersen_US
dc.subjectCrystallographyen_US
dc.subjectDFT calculationsen_US
dc.subjectX-ray crystallographyen_US
dc.subjectMultinuclear NMRen_US
dc.subjectPrimary laddered unitsen_US
dc.subjectSecondary ladderingen_US
dc.titleBackbone-substituted ß-ketoimines and ketoiminate clusters: transoid Li2O2 squares and D2-symmetric Li4O4 cubanes. Synthesis, crystallography and DFT calculationsen_US
dc.typeArticleen_US
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