Lead Tetrakis(imidazolyl)borate Solids: Anion Exchange, Solvent Intercalation, and Self Assembly of an Organic Anion
文摘
The coordination polymer Pb[B(Im)4](NO3)(xH2O), constructed by using sodium tetrakis(imidazolyl)borate and lead(II) nitrate solutions, is a layered material with the metal centers facing the interlayer spacing. As in naturallyoccurring layered minerals, this compound can readily undergo anion exchange and reversible intercalation ofsolvent water in the solid state with retention of crystallinity. We observed changes in solvent intercalation by 207Pbsolid state NMR (SSNMR) and thermogravimetric analysis (TGA). Stoichiometric exchange of 15N nitrate for nitrateand iodide for nitrate is monitored by 15N and 207Pb SSNMR, and single crystals of the iodide-exchanged materialPb[B(Im)4]I were isolated. While the iodide compound can be obtained through facile exchange from the nitrateparent compound, the organic anion benzoate is placed in the interlayer spacing for nitrate under self-assemblyconditions and forms an alternating monolayer in Pb[B(Im)4](C6H5COO)(0.5H2O). The ion exchange versus self-assembly behavior correlates with the structural differences in the three compounds. In both Pb[B(Im)4]I and Pb[B(Im)4](C6H5COO)(0.5H2O), the lead sites act as Lewis acids for the iodide and benzoate, respectively.