Consistent zincophosphite 4-ring ‘ladder’ chain structural motif with isomeric ligands

The syntheses and crystal structures of four hydro­thermally prepared organo–zinc phosphites, viz. poly[[(2-amino-3-methyl­pyridine)-μ(3)-phospho­nato-zinc] hemihydrate], {[Zn(HPO(3))(C(6)H(8)N(2))]·0.5H(2)O}( n ), (I), poly[(2-amino-4-methyl­pyridine)-μ(3)-phospho­nato-zinc], [Zn(HPO(3))(C(6)H(8)N(2))]( n ), (II), poly[(2-amino-5-methyl­pyridine)-μ(3)-phospho­nato-zinc], [Zn(HPO(3))(C(6)H(8)N(2))]( n ), (III), and poly[bis­(2-amino-4-methyl­pyridinium) [tetra-μ(3)-phospho­nato-trizinc] monohydrate], {(C(6)H(9)N(2))(2)[Zn(3)(HPO(3))(4)]·H(2)O}( n ), (IV), are described. Compounds (I)–(III) are constructed from vertex-sharing ZnO(3)N tetra­hedra (the organic mol­ecule acting as a ligand) and HPO(3) pseudo pyramids in a 1:1 ratio to generate the same motif of infinite 4-ring ‘ladder’ chains propagating in the [010], [101] and [100] directions, respectively, whereas (IV) consists of (010) layers of vertex-sharing ZnO(4) and HPO(3) units in a 3:4 ratio with the protonated organic mol­ecule acting as a template. When an excess of HCl is used in the synthesis, the simple hydrated mol­ecular salt, bis­(2-amino-3-methyl­pyridinium) tetra­chloro­zincate monohydrate, (C(6)H(8)N(2))(2)[ZnCl(4)]·H(2)O, (V), arises. Com­pounds (I)–(V) feature extensive networks of hydrogen bonds, both classical (N—H⋯O, N—H⋯Cl, O—H⋯O) and non-classical (C—H⋯O, C—H⋯Cl) in nature, which help to consolidate the extended structures.