Dynamic disorder in the high-temperature polymorph of bis[diamminesilver(I)] sulfate—reasons and consequences of simultaneous ammonia release from two different polymorphs. Issue 13 (3rd July 2021)

• Record Type: Journal Article
• Authors: Bereczki, Laura; Fogaça, Lara Alexandre; Dürvanger, Zsolt; Harmat, Veronika; Kamarás, Katalin; Németh, Gergely; Holló, Berta Barta; Petruševski, Vladimir M.; Bódis, Eszter; Farkas, Attila; Szilágyi, Imre Miklós; Kótai, László
• Is Part Of: Journal of coordination chemistry. Volume 74:Issue 13(2021)
• Page Start: 2144
• Page End: 2162
• Publication Date: 2021-07-03
• Subjects: Sulfate -- thermal decomposition -- phase transition -- DSC -- evolved gas analysis -- diamminesilver(I); Coordination compounds -- Periodicals; 541.2242
• DOI: 10.1080/00958972.2021.1953489
• Languages: English
• ISSNs: 0095-8972

Abstract

Abstract: We prepared and characterized a high-t tetragonal polymorph of diamminesilver(I) sulfate ( a = 8.6004(4) Å, c = 6.2123(6) Å) (compound 1-HT ). The phase transformation of the low-temperature polymorph of diamminesilver(I) sulfate (compound 1-LT ) into the high-temperature polymorph (compound 1-HT ) partly coincides with the initial stage of the thermal decomposition of 1-LT . Selecting appropriate conditions, we separated the two processes and determined the standard heat of formation of the LT polymorph (Δ H 298 = −1208.92 kJ/mol) and the enthalpy of polymorphic transformation (Δ HLT→HT = 13.18 kJ/mol). The high-temperature XRD results showed that the lattice constants of the LT polymorph (1-LT ) extend in the direction of a, b, and compress in the direction of c in the 1-HT polymorph. According to high temperature SXRD data, the Ag–Ag distance (in the direction of c ) shortens from 3.20 Å (1-LT ) to 3.11 Å (1-HT ), while the extension in the a, b direction weakens/disrupts the N-H…O-S hydrogen bonds and the coordinative Ag…O-S interactions. The IR and Raman spectroscopic data confirm the weakening/breaking of N-H…O-S hydrogen bonds. A vacuum-assisted thermal deammoniation experiment of 1-LT in the preparation of monoamminesilver(I) sulfate showed that the product is the mixture of silver(I) sulfate and the initial diamminesilver(I) sulfate complex. Abstract : UF0001