Hydrogen for X-Group Exchange in CH3X (X = Cl, Br, I, OMe, and NMe2) by Monomeric [1,2,4-(Me3C)3C5H2]2CeH: Experimental and Computational Support for a Carbenoid Mechanism

Reactivity Studies on Lanthanum and Cerium Hydrido Metallocenes

The alkyl complexes [5-1,3-(Me3C)2C5H3]2Ln(CH2C6H4-o-NMe2) (Ln = La 1, Ce 2) react with 9-borabicyclo[3.3.1]nonane (9-BBN) in THF to afford the lanthanum boroxide complex [5-1,3-(Me3C)2C5H3]2La(µ-OBC8H14)(THF) (3) and cerium boroxide complex [5-1,3-(Me3C)2C5H3]2Ce(µ-OBC8H14)(THF) (4)....

Catalytic N-Si coupling as a vehicle for silane dehydrocoupling via α-silylene elimination

Exploration of (N₃N)ZrNMe₂ (1, N₃N = N(CH₂CH₂NSiMe₃)₃^3-) as a catalyst for the cross-dehydrocoupling or heterodehydrocoupling of silanes and amines suggested silylene reactivity. Further studies of the catalysis and stoichiometric modeling reactions hint at α-silylene elimination as the pivotal mechanistic step, which expands the 3p elements known to engage in this catalysis and provides a new strategy for the catalytic generation of low-valent fragments.

Synthesis and molecular structure of pentadienyl complexes of the rare-earth metals

In combination with small and difficult to reduce rare-earth metals pdl′ undergoes CH-bond activations instead of sterically induced reductions to form dimeric complexes with a unique bridging six-membered metallacycle as the central structural motif.

Facile ring-opening of THF at a lithium center induced by a pendant Si-H bond and BPh3

The macrocyclic polyamine 1,4,7-trimethyl-1,4,7,10-tetraazacyclododecane [LH = (Me₃TACD)H] formed adducts with tetramethyl-silazides [M{N(SiHMe₂)₂}] (M = Li, Na, K) of light alkali metals. Upon heating, intramolecular dehydrocoupling occurred to give [M{(L)SiMe₂N(SiHMe₂)}]. BPh₃ induced facile ring-opening of THF when reacted with [Li{(L)SiMe₂N(SiHMe₂)}].

Ring-opening of cyclic ethers by aluminum hydridotriphenylborate

Ring-opening of THF or THP in the presence of pinacolborane can be catalyzed by a molecular aluminum hydride catalyst [(L)AlH₂]₂ (L = Me₃TACD)/BPh₃ and involves an isolable intermediate [(L)AlH][HBPh₃].

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

The homoleptic organocerium complex Ce{C(SiHMe₂ )₃ }₃ (1) reacts with B(C₆ F₅ )₃ to produce the zwitterionic bis(alkyl) hydridoborato Ce{C(SiHMe₂ )₃ }₂ HB(C₆ F₅ )₃ (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.

New perspectives in organolanthanide chemistry from redox to bond metathesis: insights from theory

A fifteen year contribution of computational studies carried out in close synergy with experiments is summarized.

Trinuclear alkyl hydrido rare-earth complexes supported by amidopyridinato ligands: synthesis, structures, C–Si bond activation and catalytic activity in ethylene polymerization

[(Ap^9MeLu)₃(μ²-H)₃(μ³-H)₂(CH₂SiMe₃)(thf)₂] was synthesized. For Y and Yb C–Si bond activation occurs affording [(Ap^9MeLu)₃(μ²-H)₃(μ³-H)₂(CH₂SiMe₃)(thf)₂] and [(Ap^9MeLn)₃(μ²-H)₃(μ³-H)₂(CH₂SiH₂Ph)(thf)₂].

Reversible double C-H bond activation of linear and cyclic ethers to form iridium carbenes

The double C-H bond activation of a series of linear and cyclic ethers by the iridium complex [Tp(tol')Ir(C(6)H(5))(N(2))] (2⋅N(2)), which features a cyclometalated hydrotris(3-p-tolylpyrazol-1-yl)borate ligand (Tp(tol')) coordinated in a κ(4)-N,N',N'',C manner, has been studied. Two methyl ethers, namely, Me(2)O and MeOtBu, along with diethyl ether and the cyclic ethers tetrahydrofuran, tetrahydropyran (THP), and 1,4-dioxane have been investigated with formation in every case of the corresponding hydride carbene complexes 3-8, which are stabilized by κ(4)-coordination of the ancillary Tp(tol') ligand. Five of the compounds have been structurally authenticated by X-ray crystallography. A remarkable feature of these rearrangements is the reversibility of the double C-H bond activation of Me(2)O, MeOtBu, Et(2)O, and THP. This has permitted catalytic deuterium incorporation into the methyl groups of the two methyl ethers, although in a rather inefficient manner (for synthetic purposes). Although possible in all cases, C-C coupling by migratory insertion of the carbene into the Ir-C σ bond of the metalated linkage has only been observed for complex 8 that contains a cyclic carbene that results from α,α-C-H activation of 1,4-dioxane. Computational studies on the formation of iridium carbenes are also reported, which show a role for metalated Tp ligands in the double C-H activation and account for the reversibility of the reaction in terms of the relative stability of the reagents and the products of the reaction.