The Alkylaluminate/Gallate Trap: Metalation of Benzene by Heterobimetallic Yttrocene Complexes [Cp*2Y(MMe3R)] (M = Al, Ga)

Aluminum-Boron Bond Formation by Boron Ester Oxidative Addition at an Alumanyl Anion

The potassium diamidoalumanyl, [K{Al(SiNDipp)}]2 (SiNDipp = {CH2SiMe2NDipp}2), reacts with the terminal B-O bonds of pinacolato boron esters, ROBpin (R = Me, i-Pr), and B(OMe)3 to provide potsassium (alkoxy)borylaluminate derivatives, [K{Al(SiNDipp)(OR)(Bpin)}]n (R = Me, n = 2; R = i-Pr, n = ∞) and [K{Al(SiNDipp)(OMe)(B(OMe)2)}]∞, comprising Al-B σ bonds. An initial assay of the reactivity of these species with the heteroallene molecules, N,N'-diisopropylcarbodiimide and CO2, highlights the kinetic inaccessibility of their Al-B bonds; only decomposition at high temperature is observed with the carbodiimide, whereas CO2 preferentially inserts into the Al-O bond of [K{Al(SiNDipp)(OMe)(Bpin)}]2 to provide a dimeric methyl carbonate species. Treatment of the acyclic dimethoxyboryl species, however, successfully liberates a terminal alumaboronic ester featuring trigonal N2Al-BO2 coordination environments at both boron and aluminum.

Divalent Lanthanide Tetraisobutylaluminates: Reactivity and Living Isoprene Polymerization

Lanthanide (Ln) tetraisobutylaluminates constitute key components in commercial 1,3-diene polymerization catalysts, and likewise are the homogeneous rare-earth-metal catalysts of prime industrial importance. Discrete divalent rare-earth-metal complexes [Ln(AliBu₄ )₂ ] (Ln=Sm, Eu, Yb) reported here display the first structurally characterized homoleptic metal tetraisobutylaluminates. Treatment of [Ln(AliBu₄ )₂ ] with C₂ Cl₆ gives access to Sm^II /Sm^III mixed-valence cluster [Sm₆ Cl₈ (AliBu₄ )₆ ] and the Yb^II cluster [Yb₄ Cl₄ (AliBu₄ )₄ ], respectively. Reaction with B(C₆ F₅ )₃ leads to hydride abstraction and formation of arene-coordinated hydroborates such as [Sm{HB(C₆ F₅ )₃ }₂ (toluene)₂ ]. Complexes [Ln(AliBu₄ )₂ ] engage in single-component isoprene polymerization, affording high cis-1,4 polyisoprenes with narrow molecular weight distributions. Binary [Yb(AliBu₄ )₂ ]/[HNPhMe₂ ][B(C₆ F₅ )₄ ] fabricates polyisoprene in a perfectly living manner. The catalytically active species are scrutinized by NMR spectroscopy.

Reactivity of Mixed Methyl-Aminobenzyl Guanidinate Lutetium Complex towards iPrN=C=NiPr, CS2 and Ph2PH

A heteroleptic terminal alkyl lutetium complex stabilized by a bulky guanidinato ligand, LLu(CH2C6H4NMe2-o)(Me)(THF) (1) (L = (PhCH2)2NC(NC6H3iPr2-2,6)2) has been synthesized by treatment of LLu(CH2C6H4NMe2-o)2 with AlMe3 (1 equiv) via an...