Structural variations of Sn pyridylphosphonates influenced by an uncommon Sn-N interaction

Four new Sn^II phosphonates have been synthesized by hydrothermal methods, and their structures determined by single-crystal X-ray diffraction. Tin(II) 3-pyridylphosphonate, SnO₃PC₅H₄N (I), crystallizes in P2₁/c with a=4.9595(8) Å, b=10.7673(18) Å, c=13.996(2) Å, and β=93.616(2)°. Tri-tin(II) (μ-3)-oxo-(bis)-4-pyridylphosphonate, Sn₃O(O₃PC₅H₄N)₂ (II), crystallizes in P-1 with a=7.2406(14) Å, b=9.9524(19) Å, c=12.604(3) Å, α=104.510(11)°, β=90.326(11)°, and γ=110.897(11)°. Tin(II) 6-methyl-2-pyridylphosphonate quadrahydrate, Sn(O₃PC₅H₃NCH₃)·0.25H₂O (III), crystallizes in Pna2₁, a=18.955(3) Å, b=9.7543(14) Å, and c=17.833(3) Å. Tin(II) 4-cyanophenylphosphonate, Sn(O₃PC₆H₄CN) (IV), crystallizes in P-1, a=5.0019(3) Å, b=8.4396(5) Å, c=10.3099(6) Å, α=90.352(3)°, β=94.894(3)°, and γ=92.236(4)°. I, II, and IV have ladder-type structures, and III is a layered compound. The structural variations show the effects of the Sn-N interaction on the final structures.