The structural systematics of protonation of some important nitrogen-base ligands. III. Some (univalent) anion salts of some hindered unidentate nitrogen bases
Journal Publication ResearchOnline@JCUAbstract
Recent structural studies of salts of the 2,2,6,6-tetramethylpiperidinium cation [tmpH]+ (chloride, bromide; thiocyanate) present as interesting dimeric or polymeric associations linked by pairs of directional hydrogen-bonds from the cationic = NH2+ moieties to two-coordinate anions. Present single crystal X-ray studies have characterized the iodide, perchlorate, nitrate and trifluoroacetate complexes, all, like those of the preceding studies, of composition [tmpH]+X- (anhydrous). A variety of forms are found: the nitrate compound is dimeric [[tmpH](O·NO·O)2[Htmp]], the trifluoroacetate compound being similar in form while the iodide and perchlorate salts are mixtures of dimers (with the anions essentially single atom bridges) and single-stranded helical polymers, the stoichiometric ratio of these being 1:1 and 2:1 in terms of [tmpH]X formula units, respectively. A study of 4-keto-2,2,6,6-tetramethyl-piperidinium thiocyanate shows it to be a dimer [[OtmpH](SCN/NSC)[HtmpO]] unlike its previously studied chloride analogue which is a cyclic tetramer. A new P21/n phase of di-isopropylammonium chloride, derivative of the previously described P212121 and P21 forms, is reported, together with descriptions of protonated salts of the other hindered unidentate bases 2,6-lutidine (as the chloride salt), quinoline (as the perchlorate, trifluoroacetate, hexachlorostannate and bisulfate salts) and 2-quinaldine (as the chloride (anhydrous and monohydrate) and hexachlorostannate salts), all displaying arrays derivative of ion-pair formation (extended by anion-anion hydrogen-bonds as well in the bisulfate salt) and, in the case of the aromatic bases, dominated by parallel stacking.
Journal
Zeitschrift für Anorganische und Allgemeine Chemie
Publication Name
Zeitschrift für Anorganische und Allgemeine Chemie
Volume
632
ISBN/ISSN
1521-3749
Edition
N/A
Issue
7
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Location
N/A
Publisher
Wiley-VCH
Publisher Url
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Publisher Location
Berlin, Germany
Publish Date
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Date
N/A
EISSN
N/A
DOI
10.1002/zaac.200500497