Homoleptic Rare Earth Dipyridylamides [Ln2(N(NC5H4)2)6], Ln = Ce, Nd, Sm, Ho, Er, Tm, Yb, and Sc: Metal Oxidation by the Amine Melt and in 1,2,3,

详细信息    查看全文

• 作者：Klaus M&uuml ; ller-Buschbaum and Catharina C. Quitmann
• 刊名：Inorganic Chemistry
• 出版年：2006
• 出版时间：March 20, 2006
• 年：2006
• 卷：45
• 期：6
• 页码：2678 - 2687
• 全文大小：509K
• 年卷期：v.45,no.6(March 20, 2006)
• ISSN：1520-510X

文摘

Homoleptic dimeric dipyridylamide complexes of the rare earth elements are obtained by solvent-free oxidationreactions of the metals with melts of 2,2'-dipyridylamine. As the thermal stabilities of the ligand as well as theamide complexes are limiting factors in these high-temperature syntheses, several different metal activation procedureshave been investigated: the formation of Ln amalgams and dissolution of the metals in liquid ammonia as well ascoupling to microwaves. For comparison with a solvent that shows low solubility of the metals and products, reactionsin 1,2,3,4-tetrahydroquinoline were also carried out. For all lanthanides and group 3 metals used homoleptic dimersof the formula [Ln₂(Dpa)₆], Ln = Ce (1), Nd (2), Sm (3), Ho (4), Er (5), Tm (6), Yb (7), and Sc (8) and Dpa^- =(C₅H₄N)₂N^-, were obtained, all containing trivalent rare earth ions with a distorted square antiprismatic nitrogencoordination. Due to the large differences in the ionic radii of the metal ions, two different structure types are foundthat crystallize in the space groups P2₁/c and P2₁/n with the border of the two types being between Tm and Yb.The orientations of two 1,3/1,3-double chelating and linking dipyridylamide ligands (Dpa^- = (C₅H₄N)₂N^-) result indifferent overall orientations of the dimers and thus two structure types. All compounds were identified by single-crystal X-ray analysis. Mid-IR, far IR, and Raman spectroscopy, microanalyses, and simultaneous DTA/TG as wellas mass spectrometry regarding their thermal behavior were also carried out to characterize the products. Crystaldata for the two types follow. Ce (1): P2₁/n; T = 170(2) K; a = 1063.0(1), b = 1536.0(1), c = 1652.0(2) pm; ages/gifchars/beta2.gif" BORDER=0 ALIGN="middle">= 101.60(1)ages/entities/deg.gif">; V = 2642.2(3) × 10⁶ pm³; R₁ for F_o > 4ages/gifchars/sigma.gif" BORDER=0 >(F_o) = 0.046, wR₂ = 0.120. Sc (8): P2₁/c; T = 170(2)K; a = 1073.0(1), b = 1506.2(2), c = 1619.8(2) pm; ages/gifchars/beta2.gif" BORDER=0 ALIGN="middle"> = 103.16(9)ages/entities/deg.gif">; V = 2548.9(5) × 10⁶ pm³; R₁ for F_o > 4ages/gifchars/sigma.gif" BORDER=0 >(F_o)= 0.038, wR₂ = 0.091.