Free Aluminylenes: An Emerging Class of Compounds

Abstract

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Recent advances in the chemistry of isolable carbene analogues with group 13–15 elements

“…Further reactivity explorations reveal that the Al( i ) center of compound 5 exhibits ambiphilicity (Scheme 3). 31 Compound 5 readily engages in oxidation reactions 106 with IDippCuCl or (THT)AuCl and cycloaddition reactions 110 with unsaturated hydrocarbons, yielding the respective aluminium (di)chloride products 5-P1 to 5-P2 and aluminium heterocycles 5-P3 to 5-P5 . More recently, reactivity of compound 5 towards boron Lewis acids has been explored, giving diverse aluminum–boron-bonded species 5-P6 to 5-P7 .…”

“…27 The carbene analogues mentioned above possess an electron configuration with a lone pair of electrons and a formally unoccupied p-orbital. 25,28–31 The stable versions of these analogues often exhibit a closed-shell singlet ground state. In stark contrast, their triplet variants are typically unstable, and have been primarily documented through gas-phase studies or spectroscopic means.…”

“…The electron distribution of the singlet ground state fosters carbene analogues' ambiphilic behavior, with the lone pair of electrons acting as a σ-donor and the empty p-orbital as a π–acceptor. 25,28–31 This understanding has ushered in three distinct stabilization strategies, encompassing the use of heteroatom-substituted π-donor ligands, cyclic ligands for structural rigidity, and sterically demanding ligands to counter undesired intermolecular interactions. As illustrated in Fig.…”

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

“…Although this process initially resulted in formal B–F oxidative addition and formation of a borylfluoroaluminate ( 11 ), the highly reactive tetraorganoalumaborane ( 12 ) could be liberated by treatment with Me 3 SiOTf. Even more recently, Zhang and Liu have reported that, although unreactive toward BPh 3 , treatment of the carbazolyl aluminylene ( 13 ) with Ph 2 BOBPh 2 proceeds by B–OC oxidative addition at the Al­(I) center to provide the (boryloxy)­(boryl)­alumane ( 14 ). , In this contribution, we extend this mode of reactivity to B–O oxidative addition through the reaction of 8 with readily available cyclic and acyclic borate esters. We also describe an initial assay of the reactivity of the resultant (boryl)­(alkoxy)­aluminates with heteroallenes and the transformation of a dimethoxyboryl derivative to a terminal alumaboronic ester featuring trigonal N 2 Al-BO 2 coordination environments at both boron and aluminum.…”

“…Even more recently, Zhang and Liu have reported that, although unreactive toward BPh 3 , treatment of the carbazolyl aluminylene ( 13 ) with Ph 2 BOBPh 2 proceeds by B–OC oxidative addition at the Al(I) center to provide the (boryloxy)(boryl)alumane ( 14 ). 57 , 58 In this contribution, we extend this mode of reactivity to B–O oxidative addition through the reaction of 8 with readily available cyclic and acyclic borate esters. We also describe an initial assay of the reactivity of the resultant (boryl)(alkoxy)aluminates with heteroallenes and the transformation of a dimethoxyboryl derivative to a terminal alumaboronic ester featuring trigonal N 2 Al-BO 2 coordination environments at both boron and aluminum.…”