A new bis(cyclopentadienyl) dialane is prepared, which shows controlled, selective dialumination reactions with a conventional alkyne, an electron-rich alkyne, and an azide. The reactions provide structurally diverse products, featuring a range of aluminium coordination numbers, cyclopentadienyl binding modes, and cyclic motifs. The variable nature of the bonding in the Cp*Al units allows a range of binding modes depending on the electronic requirements of the Al atom and provides new possibilities to the chemistry of dialanes, as demonstrated by the isolation of a double internal Lewis adduct with "ring-slipped" Cp* rings in this work.

The reactivity of the diaminoacetylene Pip-C≡C-Pip (Pip=piperidyl=NC H ) towards phenyldichloro- and triphenylborane is presented. In the case of the less Lewis acidic PhBCl , the first example of a double Lewis adduct of a vicinal dicarbenoid is reported. For the more Lewis acidic triphenylborane, coordination to the bifunctional carbene leads to a mild B-C bond activation, resulting in a syn-1,2-carboboration. Ensuing cis/trans isomerization yields a novel ethylene-bridged frustrated Lewis pair (FLP). The compounds were characterized using multinuclear NMR spectroscopy, structural analysis, and mass spectrometry. Reactivity studies of both isomers with the N-heterocyclic carbene 1,3-dimethylimidazol-2-ylidene (IMe) aided in elucidating the proposed isomerization pathway. DFT calculations were carried out to elucidate the reaction mechanism. The rather low free energy of activation is consistent with the observation that the reaction proceeds smoothly at room temperature.

The complete scission of the carbon-oxygen bond of carbon monoxide, while frequently observed on bulk metals and with bimetallic and cluster transition metal complexes, is unknown with monometallic systems. Reaction of a zerovalent iron bis(borylene) complex with a cyclic (alkyl)(amino)carbene revealed a highly selective intramolecular cleavage of the C-O bond of a carbonyl ligand at room temperature, leading to the formation of a highly unusual iron complex containing a base-stabilized (bora)alkylideneborane ligand. DFT investigation of the reaction mechanism suggested that the two Lewis acidic borylene boron atoms cooperate to cleave the C-O multiple bond.

A cyclopentadienyl-substituted alumole is shown to undergo ring expansions with a series of organic azides, affording 1,2-azaaluminabenzenes either with or without an azo group.