Starting materials: PbO, concentrated aqueous HI (57 % w/w), (HC(NH2)2)(O2CCH3) [OR HC(NH2)2Cl], HCl (37 % w/w), HCl (37 % w/w)

Product: HC(NH2)2PbI3 Powder

Description: "3 4.46 g (20 mmol) of PbO was dissolved in 15 mL of concentrated aqueous HI (57 % w/w) and the solution temperature was raised and held to boiling (ca. 130 °C). In a separate beaker, 2.08 g (20 mmol) of (HC(NH2)2)(O2CCH3) or 1.61 g (20 mmol) of freshly prepared HC(NH2)2Cl (prepared from (HC(NH2)2)(O2CCH3) and concentrated HCl (37 % w/w), followed by copious washing with toluene to remove excess acetic acid)4 were dissolved in 5 mL of concentrated aqueous HI (57 % w/w). The latter step was found to be necessary since commercially available HC(NH2)2Cl is extremely hygroscopic and contains hydrolysis products. Addition of the HC(NH2)2I solution to the PbI2 solution resulted immediately in a fine black precipitate. The reaction was stopped after 5 min and the solution was filtered hot under vacuum to avoid co-precipitation of hydrated phases obtained for the cooled solution. During filtration, the black solid turns to yellow, completely converting over a period of 5 to 10 min. The yellow solid was transferred in a vacuum oven and heated at 120° C overnight, yielding a black solid that is stable for a period of 20 to 30 days before converting back to the yellow phase. Note that if the latter step is performed in an evacuated ampule under static vacuum, the black phase converts to the yellow one within 5 to 10 min. The obtained black material consists of the crystallographically pure α-phase of HC(NH2)2PbI3. Yield: 9 to 10 g (70 % to 80 %)."

Method: Powder X-ray diffraction (PXRD)

Description: "High resolution synchrotron X-ray powder diffraction data were collected using beamline 11-BM at the Advanced Photon Source (APS), Argonne National Laboratory at a wavelength of 0.459200 Å. 50 mg of ground, yellow HC(NH2)2PbI3 was packed and sealed into a 0.5 mm OD Kapton capillary."

Comment: This is the paper referenced in this comment from dataset 2514: "However, the literature consensus for the alpha phase of formamidinium, including a later report by some of the same authors (https://doi.org/10.1002/anie.201609538), is that the compound crystallizes in the cubic space group Pm-3m. Those later reports are considered more accurate."

D. H. Fabini, C. C. Stoumpos, G. Laurita, A. Kaltzoglou, A. G. Kontos, P. Falaras, M. G. Kanatzidis, and R. Seshadri, Reentrant Structural and Optical Properties and Large Positive Thermal Expansion in Perovskite Formamidinium Lead Iodide, Angewandte Chemie International Edition Angewandte Chemie International Edition 55, 15392‑15396 (2016). doi: https://doi.org/10.1002/anie.201609538, 1433-7851.

Extraction method: Manual entry
Entry added on: March 4, 2025, 3:17 a.m.
Entry added by: Jakob Jakob Hagedorn Duke University
Last updated on: March 4, 2025, 3:17 a.m.
Last updated by: Jakob Jakob Hagedorn Duke University