Ammonothermal synthesis of dimorphic K-2[Zn(NH2)(4)]

作者：Richter Theresia M M; Zhang Shiyu; Niewa Rainer^*

来源：Zeitschrift fur Kristallographie, 2013, 228(8): 351-358.

DOI：10.1524/zkri.2013.1674

• Ammonothermal synthesis
• High-pressure
• Ternary amides
• Polymorphism

A new monoclinic modification of potassium tetraamidozincate was obtained (K-2[Zn(NH2)(4)], P2(1)/c, a = 746.54(8), b = 700.7(6), c = 1327.6(2) pm, beta = 106/07(1)degrees and Z = 4) from Zn and KNH2 under ammonothermal conditions (ammonobasic, 520-720 K, 92-228 MPa). A known triclinic form could be reproduced from liquid ammonia at ambient temperature. The crystal structures of both modifications are analyzed and compared. The absence of significant hydrogen-bridge bonding is indicated by large distances as well as the IR spectrum signals. Finally, the thermodynamic relations of both phases are discussed based on thermal analysis and crystal structure data. DSC measurements indicate the new monoclinic form to represent a high-temperature polymorph with respect to the known triclinic modification.

• 出版日期2013