Three Low-Dimensional Tin Oxalate and Tin Phosphate Materials: BING-4, -7, and -8

A solvothermal pyridine−HF−tin oxalate system has given rise to two new layered and one new chain crystal structures: BING-4, -7, and -8. BING-4 [SUNY at Binghamton, Structure No. 4, Sn(C 2 O 4 )(C 5 H 5 N), triclinic, P-1, a = 5.4202(6) Å, b = 8.3824(9) Å, c = 9.3506(10) Å, α = 87.982(2)°, β = 87.916(2)°, γ = 85.650(2)°, Z = 2] consists of charge-neutral chains of alternating tin and oxalate groups, with pyridine molecules completing the fifth coordination of the tin centers and capping the chains. Both BING-7 ([Sn(C 2 O 4 )F - ][NH 4 + ], monoclinic, P 2 1 / c, a = 8.2736(4) Å, b = 9.6386(5) Å, c = 7.7473(4) Å, β = 111.229(1)°, Z = 4) and BING-8 ([Sn(PO 4 H)F - ][NH 4 + ], orthorhombic, Pnma, a = 6.6789(4) Å, b = 5.3402(4) Å, c = 15.2795(10) Å, Z = 4) are anionic, fluorinated, tin oxalate and tin phosphate layers, respectively, with interlamellar charge-balancing ammonium cations. Characterization methods included single-crystal X-ray diffraction (SC-XRD), powder X-ray diffraction (PXRD), in-situ variable temperature (VT) PXRD, thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The multianalytical data indicate the structures collapse in the 200 °C range, losing their capping or interlamellar species. These Sn(II) materials extend the known chemistry of low-dimensional tin-based structures, and may be useful intercalation compounds.