Tetryl-Tetrylene Addition to Phenylacetylene

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.

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.

Accessing Cationic α-Silylated and α-Germylated Phosphorus Ylides

The synthesis and full characterization of α-silylated (α-SiCPs; 1-7) and α-germylated (α-GeCPs; 11-13) phosphorus ylides bearing one chloride substituent R3 PC(R1 )E(Cl)R2 2 (R=Ph; R1 =Me, Et, Ph; R2 =Me, Et, iPr, Mes; E=Si, Ge) is presented. The molecular structures were determined by X-ray diffraction studies. The title compounds were applied in halide abstraction studies in order to access cationic species. The reaction of Ph3 PC(Me)Si(Cl)Me2 (1) with Na[B(C6 F5 )4 ] furnished the dimeric phosphonium-like dication [Ph3 PC(Me)SiMe2 ]2 [B(C6 F5 )4 ]2 (8). The highly reactive, mesityl- or iPr-substituted cationic species [Ph3 PC(Me)SiMes2 ][B(C6 F5 )4 ] (9) and [Ph3 PC(Et)SiiPr2 ][B(C6 F5 )4 ] (10) could be characterized by NMR spectroscopy. Carrying out the halide abstraction reaction in the sterically demanding ether iPr2 O afforded the protonated α-SiCP [Ph3 PCH(Et)Si(Cl)iPr2 ][B(C6 F5 )4 ] (6 dec) by sodium-mediated basic ether decomposition, whereas successfully synthesized [Ph3 PC(Et)SiiPr2 ][B(C6 F5 )4 ] (10) readily cleaves the F-C bond in fluorobenzene. Thus, the ambiphilic character of α-SiCPs is clearly demonstrated. The less reactive germanium analogue [Ph3 PC(Me)GeMes2 ][B{3,5-(CF3 )2 C6 H3 }4 ] (14) was obtained by treating 11 with Na[B{3,5-(CF3 )2 C6 H3 }4 ] and fully characterized including by X-ray diffraction analysis. Structural parameters indicate a strong CYlide -Ge interaction with high double bond character, and consequently the C-E (E=Si, Ge) bonds in 9, 10 and 14 were analyzed with NBO and AIM methods.

Molecular Main Group Metal Hydrides

This review serves to document advances in the synthesis, versatile bonding, and reactivity of molecular main group metal hydrides within Groups 1, 2, and 12-16. Particular attention will be given to the emerging use of said hydrides in the rapidly expanding field of Main Group element-mediated catalysis. While this review is comprehensive in nature, focus will be given to research appearing in the open literature since 2001.

Tetryl-Tetrylene Addition to Phenylacetylene

Phenylacetylene adds [Ar*GeH2 -SnAr'], [Ar*GeH2 -PbAr'] and [Ar'SnH2 -PbAr*] at rt in a regioselective and stereoselective reaction. The highest reactivity was found for the stannylene, which reacts immediately upon addition of one equivalent of alkyne. However, the plumbylenes exhibit addition to the alkyne only in reaction with an excess of phenylacetylene. The product of the germylplumbylene addition reacts with a second equivalent of alkyne and the product of a CH-activation, a dimeric lead acetylide, were isolated. In the case of the stannylplumbylene the trans-addition product was characterized as the kinetically controlled product which isomerizes at rt to yield the cis-addition product, which is stabilized by an intramolecular Sn-H-Pb interaction. NMR chemical shifts of the olefins were investigated using two- and four-component relativistic DFT calculations, as spin-orbit effects can be large. Hydride abstraction was carried out by treating [Ar'SnPhC=CHGeH2 Ar*] with the trityl salt [Ph3 C][Al(OC{CF3 })4 ] to yield a four membered ring cation.