Exchange of ammine‐ and fluorido‐ligands in complex salts: The series [Cr(NH
3
)
6
][AlF
6
], [Cr(NH
3
)
5
F][SiF
6
] and K
2
[Cr(NH
3
)
4
F
2
][Si(NH
3
)
0.5
F
5.5
]
2
摘要:
AbstractThe three amminechromium(III) complex compounds [Cr(NH3)6][AlF6], [Cr(NH3)5F][SiF6] and K2[Cr(NH3)4F2][Si(NH3)0.5F5.5]2 were obtained from ammonothermal synthesis at Tmax=724 K and pmax=2120 bar. Crystal structures were determined from single crystal X‐ray diffraction. The gradual exchange of ammine ligands by fluoride ligands in the amminechromium(III) ions is reflected by an intriguing change in color. The mutual ligand exchange between ammonia ligands and fluoride ions occurs in both the cations and the anions, indicating the various dissolved species present under the synthetic conditions.
High surface area chromium(III) fluoride – Preparation and some properties
作者:Gašper Tavčar、Tomaž Skapin
DOI:10.1016/j.jfluchem.2019.04.019
日期:2019.6
Reaction of hydrated hydrazinium fluorochromate(III), [N2H6][CrF5]·H2O, with fluorine (F2) in anhydrous hydrogen fluoride (aHF) medium at room temperature yields completely amorphous CrF3-based materials with exceptionally high specific surface areas of 180–420 m2 g−1 (HS-CrF3). The stepwise reaction starts with the oxidative decomposition of the cationic part of the precursor with F2 that gives a
在室温下,无水氟化氢(aHF)介质中水合氟铬酸铬(III)[N 2 H 6 ] [CrF 5 ]·H 2 O与氟(F 2)的反应生成完全无定形的CrF 3基材料比表面积极高,为180-420 m 2 g -1(HS-CrF 3)。逐步反应从前体的阳离子部分与F 2的氧化分解开始,得到具有低表面积的CrF 3中间体。在接下来的步骤中,部分Cr 3+被氧化为Cr > 3+,并且在存在残留的H 2 O / [H 3 O] +物质的情况下,会形成Cr > 3+的氟化物。挥发性铬化合物(主要是CrO 2 F 2)的形成显然是HS-CrF 3形成的关键步骤。从最终产品中除去这些成分会降低氧含量,并产生微孔。HS-CrF 3材料完全是非晶态的,其总体组成接近化学计量的CrF 3。最终产品中的少量Cr > 3+和氧很可能源自保留的非挥发性CrOF 3。HS-CrF 3材料是路易斯酸,并且对氯氟烃(CFC