Intermolecular beta-Hydrogen Abstraction in Ytterbium, Calcium, and Potassium Tris(dimethylsilyl)methyl Compounds

TitleIntermolecular beta-Hydrogen Abstraction in Ytterbium, Calcium, and Potassium Tris(dimethylsilyl)methyl Compounds
Publication TypeJournal Article
Year of Publication2013
AuthorsYan K, Schoendorff G, Upton BM, Ellern A, Windus TL, Sadow AD
Journal TitleOrganometallics
Date Published03
Type of ArticleArticle
ISBN Number0276-7333
Accession NumberWOS:000316094900020
Keywordsagostic rigidity, aluminum complexes, ansa-lanthanidocene complexes, benzyl complexes, crystal-structures, organometallic compounds, STRUCTURAL-CHARACTERIZATION, tetrahydrofuran adduct, thermal-decomposition, x-ray structures

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.

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