| Abstract
| - We describe the single crystal data for three lead phenylphosphonates, the first such data for this class of compounds. All are layered and are polytypes of one another or previously published structures. The lead centers are umbrella-like four- or five-coordinate, or distorted eight-coordinate, connecting to the oxygens of the phosphonate groups. The phenyl rings point into the interlamellar region, capping and separating the layers. The thermal behavior of these materials is also described.
- We report the solvothermal synthesis and characterization of a series of layered lead phenylphosphonates. Thecrystals were suitable for single crystal X-ray diffraction data, and the two new structures we denote BING-6[SUNY at Binghamton, Structure No. 6, Pb(PO3C6H5)·0.25C5H5N, triclinic space group P1̄, Z = 2, a = 7.0770(4)Å, b = 9.3113(6) Å, c = 14.6785(9) Å, α = 80.456(1)°, β = 78.023(1)°, γ = 73.265(1)°] and BING-9 [Pb(PO3HC6H5)(PO3HC6H4CH3), monoclinic space group C2/c, Z = 4, a = 32.663(8) Å, b = 5.6220(13) Å, c = 8.3307(19)Å, β = 101.419(4)°]. The third structure, a polytype of BING-9, was previously known only from powder X-raydiffraction methods and is denoted 3 [Pb(PO3HC6H5)2, monoclinic space group C2/c, Z = 4, a = 31.681(6) Å, b= 5.5639(11) Å, c = 8.2515(16) Å, β = 101.814(4)°]. All three structures possess Pb(II) and P centers connectedby doubly and triply bridging oxygens. The phenyl groups cap and separate the charge-neutral layers. Thephosphonates of BING-6 are nonprotonated, and the structure therefore has a Pb/P ratio of 1:1. Neutral, partiallydisordered pyridine solvent molecules also reside in the interlamellar space, increasing the layer to layer distance.BING-9 and 3 are polytypes and contain singly protonated phosphonates, for a Pb/P ratio of 1:2. Furthercharacterization methods are discussed, including powder X-ray diffraction, in-situ variable temperature powderX-ray diffraction, thermogravimetric analysis, and scanning electron microscopy. Related work in the Ge, Sn, andMn systems is also discussed. These low-dimensional materials may be useful intercalation compounds for ion-exchange or sensor applications.
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