Homoleptic Trivalent Tris(alkyl) Rare Earth Compounds.

Homoleptic tris(alkyl) rare earth complexes Ln{C(SiHMe)} (Ln = La, 1a; Ce, 1b; Pr, 1c; Nd, 1d) are synthesized in high yield from LnITHF and 3 equiv of KC(SiHMe). X-ray diffraction studies reveal 1a-d are isostructural, pseudo-C-symmetric molecules that contain two secondary Ln↼HSi interactions per alkyl ligand (six total). Spectroscopic assignments are supported by comparison with Ln{C(SiDMe)} and DFT calculations.

Cerium-Catalyzed Hydrosilylation of Acrylates to Give α-Silyl Esters.

The homoleptic organocerium complex Ce{C(SiHMe ) } (1) reacts with B(C F ) to produce the zwitterionic bis(alkyl) hydridoborato Ce{C(SiHMe ) } HB(C F ) (2). NMR and IR 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.

Magnesium-catalyzed hydrosilylation of α,β-unsaturated esters.

ToMgHB(CF) (, To = tris(4,4-dimethyl-2-oxazolinyl)phenylborate) catalyzes the 1,4-hydrosilylation of α,β-unsaturated esters. This magnesium hydridoborate compound is synthesized by the reaction of ToMgMe, PhSiH, and B(CF). Unlike the transient ToMgH formed from the reaction of ToMgMe and PhSiH, the borate adduct persists in solution and in the solid state.

Direct hydrosilylation by a zirconacycle with β-hydrogen.

Azasilazirconacycle Cp2Zr{κ(2)-N(SiHMe2)SiHMeCH2} (1) and formaldehyde react through an uncatalyzed addition reaction (hydrosilylation) to form an exocyclic methoxysilyl-substituted zirconacycle. Although 1 contains 2-center-2-electron SiH groups, this transformation parallels the reactions of non-classical [Cp2ZrN(SiHMe2)2](+) ([2](+)) with carbonyls. Reactions of 1 with a series of nucleophilic and electrophilic agents were explored, as well as reactions of related β-SiH-containing silazidozirconium compounds, to develop a rationale for the unexpected hydrosilylation.