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The Structural Systematics of Protonation of Some Important Nitrogen‐base Ligands. III. Some (Univalent) Anion Salts of some Hindered Unidentate Nitrogen Bases
Author(s) -
Junk Peter C.,
Kepert Cameron J.,
Louis Lance M.,
Morien Travis C.,
Skelton Brian W.,
White Allan H.
Publication year - 2006
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.200500497
Subject(s) - chemistry , perchlorate , iodide , chloride , protonation , thiocyanate , denticity , bromide , dimer , medicinal chemistry , inorganic chemistry , anhydrous , hydrogen bond , crystallography , crystal structure , polymer chemistry , ion , organic chemistry , molecule
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 = ${\rm NH}^{+}_{2}$ 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 $\left [ [{\rm OtmpH}] \left (^{\rm SCN}_{\rm NSC} \right ) [{\rm HtmpO}] \right ]$ unlike its previously studied chloride analogue which is a cyclic tetramer. A new P 2 1 / n phase of di‐isopropylammonium chloride, derivative of the previously described P 2 1 2 1 2 1 and P 2 1 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.