Synthesis, Structure, and Density Functional Theory Analysis of a Scandium Dinitrogen Complex, [(C5Me4H)2Sc]2(μ-η2:η2-N2)
摘要:
Investigation of the bis(tetramethylcyclopentadienyl) metallocene chemistry of scandium has revealed that the method involving reduction of trivalent salts with alkali metals used with lanthanides can also be applied to scandium to make a dinitrogen complex of the first member of the transition metal series. ScCl3 reacts with 2 equiv of KC5Me4H to form (C5Me4H)(2)ScCl(THF), 1, which reacts with alklylmagnesium chloride to make (C8Me4H)(2)Sc(eta(3)-C3H5), 2. Complex 2 reacts with [HNEt3][BPh4] to yield [(C5Me4H)(2)Sc]-[(mu-Ph)BPh3], 3, which has just one primary Sc-C(phenyl) contact connecting the tetraphenylborate anion and the metallocene cation. Treatment of 3 with KC8 in THF under N-2 generates [(C5Me4H)(2)Sc](2)(mu-eta(2):eta(2)-N-2), which has a coplanar arrangement of scandium and nitrogen atoms within a square planar array of tetramethylcyclopentadienyl rings. Density functional calculations explain the bonding that results in the 1.239(3) angstrom N-N bond distance in the (N=N)(2-) moiety.
Synthesis and Comparative η<sup>1</sup>-Alkyl and Sterically Induced Reduction Reactivity of (C<sub>5</sub>Me<sub>5</sub>)<sub>3</sub>Ln Complexes of La, Ce, Pr, Nd, and Sm
作者:William J. Evans、Jeremy M. Perotti、Stosh A. Kozimor、Timothy M. Champagne、Benjamin L. Davis、Gregory W. Nyce、Cy H. Fujimoto、Robert D. Clark、Matthew A. Johnston、Joseph W. Ziller
DOI:10.1021/om050402l
日期:2005.8.1
previously described Ce or Pr complexes containing the (C5Me5)- ligand. The η1-C5Me5 alkyl-like reactivity of the (C5Me5)3Ln complexes was investigated with CO, ethylene, THF, and H2. The sterically induced reduction (SIR) reactivity of the (C5Me5)3Ln complexes was examined with SePPh3, AgBPh4, C8H8, and phenazine. All of these data indicate that (C5Me5)3Ln reactivity increases with decreasing size
的合成(C 5我5)3 Ce和(C 5我5)3镨从[(C 5我5)2 LN] [(μ-PH)2 BPH 2 ]和KC 5我5完成该系列的较大的镧系元素La-Nd和Sm在空间上拥挤(C 5 Me 5)3 Ln络合物,并且可以比较结构和反应性随金属尺寸的变化。这些新的(C 5 Me 5)3的合成Ln配合物需要甲硅烷基化的玻璃器皿,这在空间上更拥挤的类似物上是不必要的。(C 5 Me 5)3 Ce和(C 5 Me 5)3 Pr显示比任何先前描述的包含(C 5 Me 5)-配体的Ce或Pr配合物更长的Ln-C(C 5 Me 5)距离。在η 1 -C 5我5烷基,如(C反应性5我5)3成LN络合物用CO,乙烯,THF,和H调查2。用Se PPh 3,AgBPh 4,C 8 H 8和吩嗪检查(C 5 Me 5)3 Ln复合物的空间诱导还原(SIR)反应性。所有这些数据表明,(C 5 Me 5)3 Ln
Neutral and cationic trimethylsilylmethyl complexes of the rare earth metals supported by a crown ether: synthesis and structural characterization
作者:Stefan Arndt、Peter M. Zeimentz、Thomas P. Spaniol、Jun Okuda、Masaru Honda、Kazuyuki Tatsumi
DOI:10.1039/b305964b
日期:——
diamagnetic derivatives with triethylammonium tetraphenylborate in thf results in the clean formation of the cationic dialkyl complexes [Ln(CH2SiMe3)2(12-crown-4)(thf)y][BPh4] (Ln = Sc, Y, y = 0; Ln = Lu, y = 1), which also exhibit an exocyclic coordination of the crown ether to the cationic dialkyl lanthanide fragment.
Mechanistic studies on hydrazido(2–)-complexes. Cleavage of the nitrogen–nitrogen bond in the reaction of [Mo{NN(CH<sub>2</sub>)<sub>4</sub>CH<sub>2</sub>}(Ph<sub>2</sub>PCH<sub>2</sub>CH<sub>2</sub>PPh<sub>2</sub>)<sub>2</sub>] with acid
作者:Richard A. Henderson、G. Jeffery Leigh、Christopher J. Pickett
DOI:10.1039/dt9890000425
日期:——
omitted]H2}(NCR)(dppe)2]+. This species can either undergo slow nitrogen–nitrogencleavage or react via an acid-catalysed pathway involving trans-[MoNH[graphic omitted]H2}(NCR)(dppe)2]2+ to yield the products. The factors influencing whether protonation of hydrazido(2–)-ligands results in amine formation (N–N bondcleavage) or hydrazine formation (N–N bondcleavage) are discussed.
[Mo N [图中未示出] H 2 }(dppe)2 ](dppe = Ph 2 PCH 2 CH 2 PPh 2)与[NHEt 3 ] BPh 4之间反应的动力学,得到了[图中未示出的] H 2和[MoN(NCR)(dppe)2 ] BPh 4(RCN是溶剂; R = Me,Et或Ph)已被研究。通常,反应机理涉及两个平行途径。hydrazido(2-)-配体的初始快速质子化和溶剂分子对金属的攻击产生了分光光度法检测到的hydrazidium物种,反式-[Mo N [graphic省略] H 2 }(NCR)(dppe)2 ] +。该物种可以经历缓慢氮-氮裂解或反应经由涉及酸催化途径反式- [莫NH [图形省略1 H 2 }(NCR)(DPPE) 2 ] 2+,得到产品。讨论了影响肼基(2-)-配体的质子化导致胺形成(N–N键断裂)还是肼形成(N–N键断裂)的因素。
Yttrium-Catalyzed Addition of Benzylic CH Bonds of Alkyl Pyridines to Olefins
Cationic half‐sandwich yttrium alkyl complexes catalyze the ortho‐selective benzylic CH addition of dialkyl pyridines to various olefins, such as ethylene, 1‐hexene, styrenes, and 1,3‐conjugated dienes, to afford new alkylated and allylated pyridine derivatives (see scheme; Cp=C5Me5). A cationic half‐sandwich yttrium picolyl species, such as [CpY(2‐CH2‐6‐CH3C5H3N)]+, has been confirmed to be a key
阳离子半三明治式钇钇烷基络合物催化二烷基吡啶向各种烯烃(如乙烯,1-己烯,苯乙烯和1,3-共轭二烯)的邻位选择性苄基CH加成,以提供新的烷基化和烯丙基化的吡啶衍生物(参见方案; Cp = C 5 Me 5)。阳离子半夹心钇吡啶甲基物种,如[CPY(2-CH 2 -6-CH 3 Ç 5 ħ 3 N)] +,已被证实是在这一转变的关键活性物质。
Cationic Methyl Complexes of the Rare-Earth Metals: An Experimental and Computational Study on Synthesis, Structure, and Reactivity
作者:Mathias U. Kramer、Dominique Robert、Stefan Arndt、Peter M. Zeimentz、Thomas P. Spaniol、Ahmed Yahia、Laurent Maron、Odile Eisenstein、Jun Okuda
DOI:10.1021/ic801259n
日期:2008.10.20
Synthesis, structure, and reactivity of two families of rare-earth metalcomplexescontaining discrete methyl cations [LnMe(2-x)(thf)n]((1+x)+) (x = 0, 1; thf = tetrahydrofuran) have been studied. As a synthetic equivalent for the elusive trimethyl complex [LnMe3], lithium methylates of the approximate composition [Li3LnMe6(thf)n] were prepared by treating rare-earth metal trichlorides [LnCl3(thf)n]