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Abstract The reaction of three equivalents of LiCH(SiMe₃)₂with TiCl₃(NMe₃)₂afforded the rare homoleptic Ti(III) alkyl Ti{CH(SiMe₃)₂}₃(1) which crystallized as blue needles in 32 % yield. Single crystal X‐Ray data for1showed a trigonal pyramidal coordination geometry around titanium, which could be ascribed to weak interactions between the C−H bonds and the Ti(III) atom based on computational results. X‐band EPR spectroscopy gives spectral parameters consistent with the proposed Ti(III) formulation. Solutions of1are unstable at room temperature owing to intramolecular C−H activation that gave a dimeric Ti(IV) complex [{(Me₃Si)₂HC}Ti{μ‐CHSiMe₂CHSiMe₃}]₂(2). 

Abstract London dispersion (LD) interactions, which stem from long‐range electron correlations arising from instantaneously induced dipoles can occur between neighboring atoms or molecules, for example, between H atoms within ligand C−H groups. These interactions are currently of interest as a new method of stabilizing long bonds and species with unusual oxidation states. They can also limit reactivity by installing LD enhanced groups into organic frameworks or ligand substituents. Here, we address the most recent advances in the design of LD enhanced ligands, the sterically counterintuitive structures that can be generated and the consequences that these interactions can have on the structures and reactivity of sterically crowded heavy group 14 species. 

Abstract Careful analysis of the crystals formed in the reduction of Ar^iPr8AlI₂(Ar^iPr8=C₆H‐2,6‐(C₆H₂‐2,4,6‐ⁱPr₃)₂‐3,5‐ⁱPr₂) with sodium on sodium chloride showed them to contain the long sought‐after dialuminene Ar^iPr8AlAlAr^iPr8(1) that forms alongside the previously characterized alanediyl :AlAr^iPr8. The single crystal X‐ray structure of1revealed a nearly planar,trans‐bent C(ipso)AlAlC(ipso) core with an Al−Al distance of 2.648(2) Å. The molecular and electronic structure of1are consistent with an Al−Al double dative interaction augmented with diradical character and stabilized by dispersion interactions. Density functional theory calculations showed that the reactivity of :AlAr^iPr8with dihydrogen involves1, not :AlAr^iPr8, as the reactive species. In contrast, the reaction of :AlAr^iPr8with ethylene gave two products, the 1,4‐dialuminacyclohexane Ar^iPr8Al(C₂H₄)₂AlAr^iPr8(2) and the aluminacyclopentane Ar^iPr8Al(C₄H₈) (3), that can both form from the aluminacyclopropane intermediate Ar^iPr8Al(C₂H₄). Although the [2+2+2] cycloaddition of1with two equivalents of ethylene was also calculated to be exergonic, it is likely to be kinetically blocked by the numerous isopropyl substituents surrounding the Al−Al bond. Attempts to fine‐tune the steric bulk of the terphenyl ligand to allow stronger Al−Al bonding were unsuccessful, leading to the isolation of the sodium salt of a cyclotrialuminene, Na₂[AlAr^iPr6]₃(4), instead of Ar^iPr6AlAlAr^iPr6. 

One-electron reduction of the diplumbyne Ar^iPr6PbPbAr^iPr6 gives its radical anion in which the lead–lead bond is shortened by ca. 0.25 Å due to the population of a π-type orbital between the Pb atoms. EPR spectroscopy confirms coupling of the unpaired electron to the ²⁰⁷Pb nuclei. 

We report the reactivity of NH₃with ferrioplumbyl- and ferriostannylene complexes. DFT analysis of the Sn system describes a mechanism of reactivity and X-ray analysis shows a long Sn–N bond, giving a structural snapshot into its reversible nature. 

Thermal Sn–C cleavage in the diarylstannylene Sn(Ar^iPr4)₂(Ar^iPr4= C₆H₃-2,6-(C₆H₃-2,6-iPr₂)₂) was used to generate ˙Sn(Ar^iPr4) and ˙Ar^iPr4radicals for alkyne arylstannylation.