The characteristic features of bulk silicon surfaces are echoed in the related partially substituted—and thus unsaturated—neutral silicon clusters (siliconoids). The incorporation of siliconoids into more‐extended frameworks is promising owing to their unique electronic features, but further developments in this regard are limited by the notable absence of functionalized siliconoid derivatives until now. Herein we report the isolation and full characterization of the lithium salt of an anionic R5Si6‐siliconoid, thus providing the missing link between silicon‐based Zintl anions and siliconoid clusters. Proof‐of‐principle for the high potential of this species for the efficient transfer of the intact unsaturated R5Si6 moiety is demonstrated by clean reactions with representative electrophiles of Groups 13, 14, and 15.

Reaction of the (pentamethylcyclopentadienyl)silicon cation with the (pentamethylcyclopentadienyl)dicarbonylferrate anion leads to the formation of the crystalline, thermolabile silicon(II) compound [(η 5 -pentamethylcyclopentadienyl)dicarbonylferrio](η 3 -pentamethylcyclopentadienyl)silicon. The singlet-triplet energy difference ΔE ST is calculated to be 25.4 kcal/mol.

Small‐ to medium‐sized clusters occur in various areas of chemistry, for example, as active species of heterogeneous catalysis or as transient intermediates during chemical vapor deposition. The manipulation of stable representatives is mostly limited to the stabilizing ligand periphery, virtually excluding the systematic variation of the property‐determining cluster scaffold. We now report the deliberate expansion of a stable unsaturated silicon cluster from six to seven and finally eight vertices. The consecutive application of lithium/naphthalene as the reducing agent and decamethylsilicocene as the electrophilic source of silicon results in the expansion of the core by precisely one atom with the potential of infinite repetition.

The recent progress in the synthesis of partially substituted neutral silicon clusters (siliconoids) revealed unique structures and electronic anisotropies that are reminiscent of bulk and nano surfaces of silicon.

A new type of Si(II): A novel silylene stabilized by a Cp* and an imidazolin-2-iminato ligand has been prepared using two different methods. The X-ray crystallographic structure shows that the silicon(II) center is coordinated to an η(2)-Cp* ligand and the nitrogen atom of an imidazolin-2-iminato ligand. This silylene easily reacts with B(C(6)F(5))(3) to give a stable borane adduct having a zwitterionic resonance structure.

Main group analogues of cyclobutane‐1,3‐diyls are fascinating due to their unique reactivity and electronic properties. So far only heteronuclear examples have been isolated. Here we report the isolation and characterization of all‐silicon 1,3‐cyclobutanediyls as stable closed‐shell singlet species from the reversible reactions of cyclotrisilene c‐Si3Tip4 (Tip=2,4,6‐triisopropylphenyl) with the N‐heterocyclic silylenes c‐[(CR2CH2)(NtBu)2]Si: (R=H or methyl) with saturated backbones. At elevated temperatures, tetrasilacyclobutenes are obtained from these equilibrium mixtures. The corresponding reaction with the unsaturated N‐heterocyclic silylene c‐(CH)2(NtBu)2Si: proceeds directly to the corresponding tetrasilacyclobutene without detection of the assumed 1,3‐cyclobutanediyl intermediate.

SiSi activation: Reversible formation of a donor–acceptor complex between an N‐heterocyclic carbene and a cyclotrisilene with carbon‐based substituents shifts the electron density of the double bond and thus induces strong polarization, as shown by the significantly pyramidal tricoordinate silicon atom.

Catalytic open sandwiches: Oligo(ethyleneglycol) diethers RO(CH2CH2O)nR are degraded by the unusual catalyst Cp*Si+ (see scheme). The open coordination sphere at silicon allows up to four SiO contacts; crystal structure data of the reactive compounds [Cp*Si(dme)]+BR4− and [Cp*Si([12]crown‐4)]+BR4− (R=C6F5) show weakly bound ether molecules.