The 1:2 complex of boric acid with pyridoxine (1) crystallizes from aqueous solution as monohydrate in the triclinic space group P1. 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 1 H and 13 C NMR spectra of 1 reveal a fast proton exchange between 771 the two ligands in aqueous solution. Two new boron-pyridoxine complexes [Ph 2 B(H 2 pdn)] (2) and [B(C 2 O 4 )(H 2 pdn)] (3) (H 3 pdn ϭ pyridoxine) were prepared and characterized. In The crystal structure of 2 (monoclinic, P2 1 /c) the molecules are linked to chains by N-H···O hydrogen bonds along the b axis.

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Five novel organotin complexes with the anthraquinone dyes alizarin (1,2-dihydroxyanthraquinone) and purpurin (1,2,4trihydroxyanthraquinone) were synthesized and characterized by elemental analyses, FTIR and NMR spectroscopy ( 1 H, 13 C and 119 Sn). The crystal and molecular structures of four complexes were determined by X-ray diffraction on single crystals: [Bu 2 Sn(aliz)(H 2 O)] · C 2 H 5 OH (A1 · EtOH), [Bu 2 Sn(aliz)(dmso)] 2 (A3), [(Bu 2 Sn) 3 O(Hpurp) 2 ] (P1) and [Bu 2 Sn(Hpurp)(dmso)] 2 (P2), where H 2 aliz ϭ alizarin and H 3 purp ϭ purpurin.

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