A donor-supported silavinylidene and silylium ylides: boroles as a flexible platform for versatile Si(ii) chemistry.

Electron-deficient, -aromatic 2,5-disilyl boroles are shown to be a flexibly adaptive molecular platform with regards to SiMe mobility in their reaction with the nucleophilic donor-stabilised precursor dichloro silylene SiCl(IDipp). Depending on the substitution pattern, selective formation of two fundamentally different products of rivalling formation pathways is achieved. Formal addition of the dichlorosilylene gives the 5,5-dichloro-5-sila-6-borabicyclo[2.

Linear and Bent Cp* Si: Reversible Phase Transition of a Key Molecule.

The solid-state structure of decamethylsilicocene Cp* Si with a bent and a linear molecule in the same unit cell was so far considered an exception in relation to the structures of its all-bent heavier analogues Cp* E with E=Ge, Sn, Pb. Here, we present the solution to this conundrum by reporting a low-temperature phase, where all three symmetrically independent molecules are present in a bent formation. This reversible enantiotropic phase transition occurs in the temperature range between 80 K and 130 K and provides a rationale for the unexpected linear molecule based in entropy beyond hand-waving explanations such as electronic reasons or packing effects.

Borole-based half-sandwich complexes of germanium and tin.

The synthesis and initial observations regarding the reactivity of borole-based half-sandwich complexes with apical divalent group 14 elements germanium and tin are described. The 2,5-disilylborole substitution pattern allows their access salt metathesis of the respective borole dianions.

A Neutral Silicon(II) Half-Sandwich Compound.

Metathesis reaction of a dilithio borole dianion, a cyclic π-ligand isoelectronic to ubiquitous cyclopentadienyls, with two equivalents of "silicocenium" cation [Cp*Si] as a source of low-valent Si(II), cleanly gives a borole half-sandwich π-complex of Si(II) and silicocene. The resulting half-sandwich complex is a neutral isoelectronic analogue to the iconic silicocenium cation and features the rare structural motif of an apical silicon(II) atom with an energetically high lying lone pair of electrons that is shown to be accessible for coordination chemistry toward tungsten carbonyl. Protonation at the Si(II) atom with [H(OEt)][Al{OC(CF)}] induces formal oxidation, and the compound rearranges to incorporate the Si atom into the carbocyclic base to give an unprecedented cationic 5-sila-6-borabicyclo[2.