Metal-betaine interactions. Part XII

Two copper(II) complexes of pyridine betaine (C₅H₅N⁺CH₂COO^–; pyBET) were prepared and characterized by X-ray crystallography. In [Cu(pyBET)(H₂O₂)₂(SO₄)]_n (1), each Cu (II) atom is in a distorted square-pyramidal environment surrounded by a carboxylato oxygen atom [1.944(5) Å], two oxygen atoms [1.921 (5) basal, 2.268(5) apical Å] from different sulfato groups, and two aqua ligands [1.944(4) Å]. The primary coordination sphere is extended into a zigzag chain through sulfato bridging linkages, and hydrogen bonding involving the aqua ligands generates a three-dimensional network. [Cu(pyBET)(H₂O)₂Cl₂]·H₂O (2) features a discrete metal complex with its distorted square-pyramidal coordination sites occupied by a carboxylato oxygen atom [2.000(2) Å], two aqua ligands [1.968(3) Å], and two chloro ligands [2.266(1), 2.469(1) Å] of which one is apical. The lattice water molecules form hydrogen bonds with the aqua and chloro ligands to yield a layer structure.