Intermolecular β-Hydrogen Abstraction in Ytterbium, Calcium, and Potassium Tris(dimethylsilyl)methyl Compounds
摘要:
A series of organometallic compounds containing the tris(dimethylsilyl)methyl ligand are described. The potassium carbanions KC(SiHMe2)(3) and {KC(SiHMe2)(3)-TMEDA}(2) are synthesized by deprotonation of the hydrocarbon HC(SiHMe2)(3) with potassium benzyl. {KC(SiHMe2)(3)-TMEDA}(2) crystallizes as a dimer with two types of three-center-two-electron K-H-Si interactions: side-on coordination of SiH (angle K-H-Si = 102(2)degrees) and more obtuse K-H-Si structures (angle K-H-Si approximate to 150 degrees). The divalent calcium and ytterbium compounds M{C(SiHMe2)(3)}(2)L (M = Ca, Yb; L = 2THF, TMEDA) are prepared from MI2 and 2 equiv of KC(SiHMe2)(3). Low (1)J(SiH) coupling constants in the NMR spectra, low-energy nu(SiH) bands in the IR spectra, and short M-Si distances and small M-C-Si angles in the crystal structures suggest beta-agostic interactions on each C(SiHMe2)(3) ligand. The IR assignments of M{C(SiHMe2)(3)}(2)L (L = 2THF, TMEDA) are supported by DFT calculations. The compounds M{C(SiHMe2)(3)}(2)L react with 1 or 2 equiv of B(C6F5)(3) to give the 1,3-disilacyclobutane {Me2SiC(SiHMe2)(2)}(2) and MC(SiHMe2)(3)HB(C6F5)(3)L or M{HB(C6F5)(3)}(2)L, respectively. In addition, M{C(SiHMe2)(3)}(2)L compounds react with BPh3 to give beta-H abstracted products. The compounds M{C(SiHMe2)(3)}(2)THF2 react with SiMe3I to yield Me3SiH and disilacyclobutane as the products of beta-H abstraction, while M{C(SiHMe2)(3)}(2)TMEDA and Me3SiI form a mixture of Me3SiH and the alkylation product Me3SiC(SiHMe2)(3) in a 1:3 ratio.
Interconverting Lanthanum Hydride and Borohydride Catalysts for C=O Reduction and C−O Bond Cleavage
作者:Smita Patnaik、Aaron D. Sadow
DOI:10.1002/anie.201813305
日期:2019.2.18
highlighted by C−O bondcleavage in the hydroboration of esters and epoxides at room temperature. The catalytic hydroboration tolerates functionality typically susceptible to insertion, reduction, or cleavage reactions. Turnover numbers (TON) up to 10 000 are observed for aliphatic esters. Lanthanum hydrides, generated by reactions with pinacolborane, are competent for reduction of ketones but are
作者:Aradhana Pindwal、KaKing Yan、Smita Patnaik、Bradley M. Schmidt、Arkady Ellern、Igor I. Slowing、Cheolbeom Bae、Aaron D. Sadow
DOI:10.1021/jacs.7b09521
日期:2017.11.22
Homoleptic tris(alkyl) rareearth complexes LnC(SiHMe2)3}3 (Ln = La, 1a; Ce, 1b; Pr, 1c; Nd, 1d) are synthesized in high yield from LnI3THFn and 3 equiv of KC(SiHMe2)3. X-ray diffraction studies reveal 1a–d are isostructural, pseudo-C3-symmetric molecules that contain two secondary Ln↼HSi interactions per alkyl ligand (six total). Spectroscopic assignments are supported by comparison with LnC(SiDMe2)3}3 and
Cerium-Catalyzed Hydrosilylation of Acrylates to Give α-Silyl Esters
作者:Aradhana Pindwal、Smita Patnaik、William C. Everett、Arkady Ellern、Theresa L. Windus、Aaron D. Sadow
DOI:10.1002/anie.201610263
日期:2017.1.9
spectroscopy and X‐ray crystallography indicate that each alkyl ligand contains two bridging Ce↼H‐Si interactions in both 1 and 2. Compound 2 serves as a precatalyst for the hydrosilylation of acrylates to give α‐silyl esters at room temperature with a turnover number of 2200.
均相有机铈配合物Ce C(SiHMe 2)3 } 3(1)与B(C 6 F 5)3反应生成两性离子双(烷基)氢硼酸盐Ce C(SiHMe 2)3 } 2 HB(C 6 F 5)3(2)。NMR,IR光谱和X射线晶体学表明,每个烷基配体在1和2中都包含两个桥接的Ce↼H-Si相互作用。化合物2 用作丙烯酸酯的硅氢加成反应的预催化剂,在室温下以2200的营业额产生α-甲硅烷基酯。
POLYMERIZATION CATALYSTS
申请人:Iowa State University Research Foundation, Inc.
公开号:US20170275402A1
公开(公告)日:2017-09-28
The present invention relates to processes for polymerizing unsaturated hydrocarbon monomers. The present invention also relates to a precatalyst having the structure of Formula (I):
MC(SiHAlk
2
)
3
}
3
(I),
and to a catalyst comprising the structure of Formula (II):
MC(SiHAlk
2
)
3
X
2
(II),
and methods for preparation thereof.
A tris(alkyl)yttrium compound containing six β-agostic Si–H interactions
作者:KaKing Yan、Andrew V. Pawlikowski、Chris Ebert、Aaron D. Sadow
DOI:10.1039/b818630h
日期:——
The new homoleptic rare earth compound [Y(C(SiHMe2)3)3] (2) is prepared in 82% yield by salt metathesis of YCl3 and 3 equivalents of [KC(SiHMe2)3] (1); two β-agostic Yâ¯(HâSi) interactions are observed for each C(SiHMe2)3 ligand in 2, giving six agostic interactions per yttrium(III) center.