Y3MnAu5: Three Distinctive d-Metal Functions in an Intergrown Cluster Phase

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• 作者：Saroj L. Samal ; Abhishek Pandey ; David C. Johnston ; John D. Corbett
• 刊名：The Journal of the American Chemical Society
• 出版年：2013
• 出版时间：January 16, 2013
• 年：2013
• 卷：135
• 期：2
• 页码：910-917
• 全文大小：533K
• 年卷期：v.135,no.2(January 16, 2013)
• ISSN：1520-5126

文摘

The new Y₃MnAu₅ intermetallic phase is obtained from the arc-melted elements in virtually quantitative yields after annealing at 1000 掳C for 3 d. Its remarkable structure [rhombohedral, R3̅, Z = 6; a = 8.489(1) 脜, c = 18.144(2) 脜] consists of a 2:1 cubic-close-packed intergrowth between edge-shared Mn-centered Au rhombohedra (Mn@Au₈) with gold-centered antiprismatic (Au@Y₆) clusters via a common gold network. Magnetic susceptibility (蠂) data for Y₃MnAu₅ were fitted by a Curie鈥揥eiss law. The Curie constant indicates a large effective moment corresponding to nearly localized Mn spins S = 5/2, and the Weiss temperature demonstrates the dominance of ferromagnetic (FM) interactions. An antiferromagnetic (AFM) transition at T_N = 75 K and a possible spin reorientation transition at 65 K were observed. Analysis of the 蠂 data for T < T_N suggests a planar noncollinear helical AFM structure that arises from competing AFM interactions between FM-aligned layers of spins in the ab-plane with a turn angle of 69掳 between the spins along the helix c-axis. A magnetic field-induced spin flop transition is observed below T_N. Spin-polarized LMTO-LSDA calculations indicate an 2 eV splitting of the Mn 3d states and a metallic ground state, and their COHP analyses demonstrate that 81% of the total Hamilton populations originate from heteroatomic polar Y鈥揂u and Mn鈥揂u bonding. The Mn 3d, Y 4d, and Au 5d characteristics are remarkably diverse: localized and magnetically polarized for Mn; reducing and cationic for Y; and relativistically strongly bonded and oxidizing for Au, bonding of the latter two being broadly delocalized.