"114"‐Type Nitrides LnAl(Si4−xAlx)N7Oδ with Unusual [AlN6] Octahedral Coordination. Issue 14 (28th February 2017)

• Record Type: Journal Article
• Authors: Huang, Saifang; Huang, Zhaohui; Cao, Peng; Zujovic, Zoran; Price, Jason R.; Avdeev, Maxim; Que, Meidan; Suzuki, Furitsu; Kido, Tsuyoshi; Ouyang, Xin; Kaji, Hironori; Fang, Minghao; Liu, Yan‐gai; Gao, Wei; Söhnel, Tilo
• Is Part Of: Angewandte Chemie international edition. Volume 56:Issue 14(2017)
• Page Start: 3886
• Page End: 3891
• Publication Date: 2017-02-28
• Subjects: aluminum -- [AlN6] octahedron -- nitrides -- NMR spectroscopy -- structure elucidation; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.201612488
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: Aluminum–nitrogen six‐fold octahedral coordination, [AlN6 ], is unusual and has only been seen in the high‐pressure rocksalt‐type aluminum nitride or some complex compounds. Herein we report novel nitrides LnAl(Si4− x Alx )N7 O δ (Ln=La, Sm), the first inorganic compounds with [AlN6 ] coordination prepared via non‐high‐pressure synthesis. Structure refinements of neutron powder diffraction and single‐crystal X‐ray diffraction data show that these compounds crystallize in the hexagonal Swedenborgite structure type with P 63 mc symmetry where Ln and Al atoms locate in anticuboctahedral and octahedral interstitials, respectively, between the triangular and Kagomé layers of [SiN4 ] tetrahedra. Solid‐state NMR data of high‐purity La‐114 powders confirm the unusual [AlN6 ] coordination. These compounds are the first examples of the "33‐114" sub‐type in the "114" family. The additional site for over‐stoichiometric oxygen in the structure of 114‐type compounds was also identified. Abstract : Six Ns and an Al : An extremely unusual coordination, [AlN6 ], is found in the La‐114 compound LnAl(Si4− x Alx )N7 O δ (Ln=La, Sm) prepared at normal pressure. The crystal structure confirms the existence of the octahedral coordination, as does 27 Al NMR spectroscopy using La‐114 powders, giving a chemical shift of δ=3.5 ppm. The extra oxygen atoms distribute in a disordered manner surrounding [AlN6 ] octahedra.