The Structural Systematics of Protonation of Some Important Nitrogen-Base Ligands. V Some Univalent Anion Salts of Mono- and Bis(2-picolyl)amine

P.C. Junk, Y. Kim, Brian Skelton, Allan White

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

A variety of salts derivative of bis(2-picolyl)amine, 'dipic' = [{(C5NH4)(CH2)}(2)NH] in various stages of protonation have been structurally characterized, showing a considerable diversity of hydrogen-bonding modes and interactions. For the triprotonated species (protonating hydrogen atoms on all three nitrogen atoms) the arrays are haphazard [picH(3)]X-3, X = Cl(center dot H2O), I(center dot H2O), NO3, tfs (= trifluoromethanesulfonate)(center dot H2O). For the diprotonated species, diverse forms are also found: in [dipicH(2)]Br-2, the central nitrogen atom and one of the peripheral are protonated, but in the remainder, both peripheral nitrogen atoms are protonated, leading to a propensity to chelating interactions with an anion (as in the mixed anion salts Cl-center dot I-3(-) and I-I3-, where I-3(-) does not interact) or a water molecule (in the I center dot 2H(2)O salt) or anion (in the tfs salt) oxygen atom; in the nitrate salt, the ligand is twisted so that each pyridinium component interacts with an independent nitrate. By contrast, in the singly protonated species, [dipicH]X, the central nitrogen atom is protonated in all cases (X = Br, I, ClO4, thf). The tfs(-) salt is remarkable, containing a pair of cations with self-interactions. In [picH]X only the aliphatic nitrogen is protonated (X = I-, NO3-, ClO4-, tfa(-) (= trifluoroacetate)). A single example of a diprotonated species [picH(2)]Cl-2 has also been defined.
Original languageEnglish
Pages (from-to)1340-1350
JournalZeitschrift fuer Anorganische und Allgemeine Chemie
Volume632
Issue number7
DOIs
Publication statusPublished - 2006

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