Preparation and Characterization of Boron Chelates with Pyridoxine. The Crystal and Molecular Structures of [B(H2pdn)(Hpdn)]·H2O and [Ph2B(H2pdn)] (H3pdn = Pyridoxine)

• Published in: Zeitschrift für anorganische und allgemeine Chemie (1950) 2007-05, Vol.633 (5-6), p.771-775
• Main Authors: de Sousa, Adriana T., Bessler, Karl E., Lemos, Sebastia-o S., Gomes, Fernanda B., Casagrande, Gleison A., Schulz Lang, Ernesto
• Format: Article
• Language: English
• Subjects: Boron chelates; Crystal structures; NMR Spectra; Pyridoxine
• ISSN: 0044-2313; 1521-3749
• DOI: 10.1002/zaac.200600388

The 1:2 complex of boric acid with pyridoxine (1) crystallizes from aqueous solution as monohydrate in the triclinic space group ${\rm P}{\bar 1}$. The molecular structure of 1 corresponds to the expected bis‐chelate containing two non‐equivalent pyridoxinate ligands, one of them being dianionic and the other one monanionic, betain‐like with a protonated pyridine nitrogen atom. In the crystal structure hydrogen bonding, involving the water molecule, provides a supramolecular arrangement in form of sheets parallel to [011]. The 1H and 13C NMR spectra of 1 reveal a fast proton exchange between the two ligands in aqueous solution. Two new boron‐pyridoxine complexes [Ph2B(H2pdn)] (2) and [B(C2O4)(H2pdn)] (3) (H3pdn = pyridoxine) were prepared and characterized. In The crystal structure of 2 (monoclinic, P21/c) the molecules are linked to chains by N‐H···O hydrogen bonds along the b axis.