Sodium complexes of aminotroponiminate (ATI) ligands have been reacted with a range of neutral donor ligands. Upon addition of crown ethers, they undergo an unusual ligandinduced disproportionation reaction with formation of [Na(A-TI) 2 ] À sodiate complex anions. The same structural motif has also been found in the first well-defined mixed-metal ATI complexes, which have been accessed starting from monometallic sodium and potassium species. The mixed-metal compounds confirm the possibility of ATIs to act as ditopic ligands. Using the polymerization of e-caprolactone as a model system, structure-reactivity-relationships in sodium and mixed-metal ATI compounds have been studied by comparing the reactivity of [Na(ATI)] and [Na(ATI) 2 ] À structural motifs. These studies revealed trends in the catalyst activity depending on the nuclearity of the complex and the substitution pattern at the ATI ligand. Exceptionally high activities were obtained for dinuclear sodium sodiates of type [Na(crown) 2 ][Na(ATI) 2 ], making them the most active alkali metal initiators for this reaction. The organometallic and polymeric compounds presented in this work have been characterized by techniques including (VT-)NMR spectroscopy, single-crystal X-ray diffraction, gel permeation chromatography, mass spectrometry, and DFT calculations.

The reduction of a carbene‐coordinated, sterically encumbered terphenyl‐substituted aluminium diiodide, (LRAlI2), yielded a “masked” dialumene (LRAl=AlRL), self‐stabilised through [2+2] cycloaddition with a peripheral aromatic group. During the course of the reaction, a carbene‐stabilised arylalumylene (LRAl:) was generated in situ, which was trapped using an alkyne, generating an aluminacyclopropene or a C−H activated product thereof, depending on the steric bulk of the alkyne. The masked dialumene also underwent intramolecular cycloreversion and dissociation into alumylene fragments, which reacted with various organic azides to yield monomeric or dimeric iminoalanes depending on the sterics of the azide substituent. The thermodynamics of monomeric and dimeric iminoalane formation were probed by theoretical calculations.

The formation of salicylaldimine derivatives via ring contraction as byproducts in 2-aminotropone syntheses has been investigated. Salicylaldiminate (SAI) complexes of the alkali metals Li–K have been synthesized and transformed into heterobimetallic complexes. Important findings include an unusual double heterocubane structure of the homometallic sodium SAI, an unprecedented ligand-induced E/Z isomerization of the aldimine functional group in the homometallic potassium SAI, and the first example of a structurally authenticated mixed-metal SAI based on s-block central atoms. Rapid equilibria have been shown to play a crucial role in the solution phase chemistry of mixed-metal SAIs. Analytical techniques applied in this work include (heteronuclear) NMR spectroscopy, VT- and DOSY NMR spectroscopy, high-resolution mass spectrometry, single-crystal X-ray diffraction analysis, and DFT calculations.