Snapshots of sequential polyphosphide rearrangement upon metallatetrylene addition

Applications of low-valent compounds with heavy group-14 elements

Over the last two decades, the low-valent compounds of group-14 elements have received significant attention in several fields of chemistry owing to their unique electronic properties. The low-valent group-14 species include tetrylenes, tetryliumylidene, tetrylones, dimetallenes and dimetallynes. These low-valent group-14 species have shown applications in various areas such as organic transformations (hydroboration, cyanosilylation, N-functionalisation of amines, and hydroamination), small molecule activation (e.g. P4, As4, CO2, CO, H2, alkene, and alkyne) and materials. This review presents an in-depth discussion on low-valent group-14 species-catalyzed reactions, including polymerization of rac-lactide, L-lactide, DL-lactide, and caprolactone, followed by their photophysical properties (phosphorescence and fluorescence), thin film deposition (atomic layer deposition and vapor phase deposition), and medicinal applications. This review concisely summarizes current developments of low-valent heavier group-14 compounds, covering synthetic methodologies, structural aspects, and their applications in various fields of chemistry. Finally, their opportunities and challenges are examined and emphasized.

Activation of non-polar bonds by an electron-rich gallagermylene

The electron-rich germylene LGa(μ-Cl)GeArMes (1) (L = CH[C(Me)N(Dipp)]2, Dipp = 2,6-iPr2C6H3, ArMes = 2,6-Mes2C6H3, Mes = 2,4,6-Me3C6H2) shows promising potential in the σ-bond activation of unpolar molecules as is shown in oxidative addition reactions with H2 and P4, yielding L(Cl)GaGe(H)2ArMes (2) and L(Cl)Ga(P4)GeArMes (3). Compounds 2 and 3 were characterised spectroscopically (1H, 13C{1H}, (31P{1H}), IR) and by single-crystal X-ray diffraction (sc-XRD).

Multiple ethylene activation by heteroleptic L(Cl)Ga-substituted germylenes

Ethylene insertion into the Ga-Ge bond of the L(Cl)Ga-substituted germylene LGa(μ-Cl)GeDMP 1 (L = HC(C(Me)NAr)2, Ar = 2,6-iPr2C6H3; DMP = 2,6-Mes2C6H3, Mes = 2,4,6-Me3C6H2) at ambient temperature is followed by dimerization of the as-formed germylene to give the digermene 3, which further reacted with ethylene in a [2 + 2] cycloaddition to give the 1,2-digermacyclobutane 4. In marked contrast, the amino-substituted germylene L(Cl)GaGeN(SiMe3)Ar 2 reacted directly to the 1,2-digermacyclobutane 5. Quantum chemical calculations confirmed the assumed reaction mechanism, hence demonstrating the crucial role of the substituent on the reaction mechanism.