Ammonia Uptake and Release in the MnX2–NH3 (X = Cl, Br) Systems and Structure of the Mn(NH3)nX2 (n = 6, 2) Ammines

Crystals

Hazel Reardon¹  James M. Hanlon¹  Michael Grant¹  Imogen Fullbrook¹ 

[1] WestCHEM, School of Chemistry, University of Glasgow, Joseph Black Building, Glasgow G12 8QQ, UK;

关键词: manganese;    ammines;    chloride;    bromide;    structure;    Raman;    ammonia storage;    hydrogen storage;   

DOI  :  10.3390/cryst2020193

来源: mdpi

【 摘 要 】

Hexa-ammine complexes, Mn(NH₃)₆X₂ (X = Cl, Br), have been synthesized by ammoniation of the corresponding transition metal halide and characterized by Powder X-ray diffraction (PXRD) and Raman spectroscopy. The hexa-ammine complexes are isostructural (Cubic, Fm-3m, Z = 4; a = 10.2742(6) Å and 10.527(1) Å for X = Cl, Br respectively). Temperature programmed desorption (TPD) demonstrated that ammonia release from Mn(NH₃)₆X₂ complexes occurred in three stages corresponding to the release of 4, 1 and 1 NH₃ equivalents respectively. The chloride and bromide both exhibit a deammoniation onset temperature below 323 K. The di-ammoniates from the first desorption step were isolated during TPD measurements and their crystal structures determined by Rietveld refinement against PXRD data (X = Cl: orthorhombic Cmmm, a = 8.1991(9) Å, b = 8.2498(7) Å, c = 3.8212(4) Å, Z = 2; X = Br: orthorhombic Pbam, a = 6.0109(5) Å, b = 12.022(1) Å, c = 4.0230(2) Å, Z = 2).

【 授权许可】

CC BY   
© 2012 by the authors; licensee MDPI, Basel, Switzerland.