Lanthanide N,N-Dimethylaminodiboranates as a New Class of Highly Volatile Chemical Vapor Deposition Precursors
Lanthanide N,N-Dimethylaminodiboranates as a New Class of Highly Volatile Chemical Vapor Deposition Precursors
复制标题
DOI：
10.1021/ic201852j
复制
发表时间：
2012-07-02
影响因子：
4.6
通讯作者：
Girolami, Gregory S.
中科院分区：
文献类型：
--
作者：
Daly, Scott R.;Kim, Do Young;Girolami, Gregory S.
合成了新的镧系元素N，N-二甲基氨基二硼化物（DMADB）配合物Ln（H_3BNMe_2BH_3）（3）和Ln（H_3BNMe_2BH_3）（3）（thf），其中Ln =钇、镧、铈、镨、钕、钐、钆、铽、镝、钬、铒、铥和镥，不同之处在于Eu和Yb的去溶剂化配合物的分离被证明是困难的。四氢呋喃（thf）配合物都是单体，并且它们中的大多数采用13配位结构，其中每个DMADB基团通过四个B-H中心点中心点Ln桥（每个BH 3基团是kappa H-2;即，形成两个B-H中心点Ln相互作用）。对于最小的三种镧系元素Tm、Yb和Lu，金属中心是12配位的，因为DMADB基团之一仅通过三个B-H中心点Ln桥螯合到金属中心。无碱Ln（H_3BNMe_2BH_3）（3）配合物的结构高度依赖于镧系离子的尺寸：随着离子半径的减小，配位数从14（Pr）减小到13（Sm）再减小到12（Dy，Y，Er）。14配位络合物是聚合的：每个金属中心结合到两个螯合DMADB配体和以Ln（kappa H-3-H3 BNMe 2BH 3-kappa H-3）Ln方式桥接的两个配体的两个“末端”。在13配位配合物中，所有三个DMADB配体都是螯合的，但金属原子也与相邻分子的一个氢原子配位。12配位配合物采用双核结构，其中每个金属中心与两个螯合DMADB配体结合，并与两个配体的两端结合，这两个配体以Ln（kappa H-2-H3 BNMe 2BH 3-kappa H-2）Ln方式桥接。配合物与水反应，部分水解产物[La（H3 BNMe 2BH 3）（2）（OH）]（4）采用镧和氧原子形成扭曲立方体的结构;每个镧原子连接到三个桥接羟基和两个螯合DMADB配体。每个螯合DMADB配体的一个B H键形成与相邻金属中心的桥。场电离MS数据，熔点和分解点，热重数据，和NMR数据，包括顺磁性镧系元素诱导的位移（LIS）的分析，报告所有的配合物。Ln（H3 BNMe 2BH 3）（3）化合物在真空中在低至65摄氏度的温度下具有高度挥发性和升华性，适合用作薄膜的化学气相沉积（CVD）和原子层沉积（ALD）前体。
New lanthanide N,N-dimethylaminodiboranate (DMADB) complexes of stoichiometry Ln(H3BNMe2BH3)(3) and Ln(H3BNMe2BH3)(3)(thf) have been prepared, where Ln = yttrium, lanthanum, cerium, praseodymium, neodymium, samarium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, and lutetium, except that isolation of the desolvated complexes proved difficult for Eu and Yb. The tetrahydrofuran (thf) complexes are all monomeric, and most of them adopt 13-coordinate structures in which each DMADB group chelates to the metal center by means of four B-H center dot center dot center dot Ln bridges (each BH3 group is kappa H-2; i.e., forms two B-H center dot center dot center dot Ln interactions). For the smallest three lanthanides, Tm, Yb, and Lu, the metal center is 12 coordinate because one of the DMADB groups chelates to the metal center by means of only three B-H center dot center dot center dot Ln bridges. The structures of the base-free Ln(H3BNMe2BH3)(3) complexes are highly dependent on the size of the lanthanide ions: as the ionic radius decreases, the coordination number decreases from 14 (Pr) to 13 (Sm) to 12 (Dy, Y, Er). The 14-coordinate complexes are polymeric: each metal center is bound to two chelating DMADB ligands and to two "ends" of two ligands that bridge in a Ln(kappa H-3-H3BNMe2BH3-kappa H-3)Ln fashion. In the 13-coordinate complexes, all three DMADB ligands are chelating, but the metal atom is also coordinated to one hydrogen atom from an adjacent molecule. The 12-coordinate complexes adopt a dinuclear structure in which each metal center is bound to two chelating DMADB ligands and to two ends of two ligands that bridge in a Ln(kappa H-2-H3BNMe2BH3-kappa H-2)Ln fashion. The complexes react with water, and the partial hydrolysis product [La(H3BNMe2BH3)(2)(OH)](4) adopts a structure in which the lanthanum and oxygen atoms form a distorted cube; each lanthanum atom is connected to three bridging hydroxyl groups and to two chelating DMADB ligands. One B H bond of each chelating DMADB ligand forms a bridge to an adjacent metal center. Field ionization MS data, melting and decomposition points, thermogravimetric data, and NMR data, including an analysis of the paramagnetic lanthanide induced shifts (LIS), are reported for all of the complexes. The Ln(H3BNMe2BH3)(3) compounds, which are highly volatile and sublime at temperatures as low as 65 degrees C in vacuum, are suitable for use as chemical vapor deposition (CVD) and atomic layer deposition (ALD) precursors to thin films.