Synthesis, spectroscopic studies, and single crystal X-ray diffraction analysis of a lead(II) based hybrid perovskite: Morpholinium trichloroplumbate(II)

Morpholinium trichloroplumbate(II), [cyclo-O(CH2CH2)2NH]PbCl3 (1), has been synthesized and characterized by elemental analysis, FTIR and 1H and 13C NMR spectroscopy, thermogravimetric analysis (TGA), diffuse reflectance spectra, and single-crystal X-ray diffraction analysis. An FTIR spectrum showed a shift of 100 cm-1 in the NH2 stretching due to the protonated nitrogen of the morpholinium ion. 1H NMR spectrum of the compound showed significant high-frequency shift of the resonance for the CH2 protons due to the presence of cationic charge on the adjacent nitrogen and hydrogen bonded interactions. Contrary to 1H NMR, the 13C NMR signals showed a lowering of 'δ' in the hybrid material. A diffuse reflectance spectrum (DRS) illustrated intense charge transfer in the compound. The observed band gap value for the compound is 3.23 eV based on the DRS data. TG-DT analysis showed the compound to be stable up to 241°C. Single crystal X-ray diffraction analysis of the hybrid material showed the Pb2+ ion being surrounded by six chloride anions in a distorted octahedral geometry. In addition to the six chloride anions, the oxygen atom of the morpholinium cation is also in short contact with the lead cation. Bond valence sum (BVS) calculation confirmed the formal oxidation state of lead to be +2. Continuous symmetry measure (CSM) calculations indicated the PbCl6 to be a distorted octahedron with a magnitude of 5.246 clearly far away from the trigonal prismatic geometry.