Aromaticity Suppression by Intermolecular Coordination. Optical Spectra and Electronic Structure of Heavy Carbene Analogues with an Amidophenolate Backbone

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.

Estimating structure, stability, and electronic properties on halogenated derivatives of 2-germabicyclo[1.1.1.]pentane-2-ylidenes at density functional theory

In this computational survey, substituent effects of group 17 on the stability (singlet-triplet energy gaps, ΔE_s-t) and reactivity of singlet (s) and triplet (t) forms of 2-germabicyclo[1.1.1.]pentane-2-ylidenes are considered by using B3LYP/6-311 +  + G**, B3LYP/aug-cc-pvtz, and B3LYP/def2-TZVP level of theories. In all germylene structures, singlets appear more stable than their corresponding triplet congeners, revealing a singlet ground state and the order of stability appears to be 1,3,4,4,5,5-hexachloro-2-germabicyclo[1.1.1.]pentane-2-ylidenes (3) > 1,3,4,4,5,5-hexabromo-2-germabicyclo[1.1.1.]pentane-2-ylidenes (4) > 1,3,4,4,5,5-hexafluoro-2-germabicyclo[1.1.1.]pentane-2-ylidenes (2) > 1,3,4,4,5,5-hexaiodo-2-germabicyclo[1.1.1.]pentane-2-ylidenes (5) > 2-germabicyclo[1.1.1.]pentane-2-ylidenes (1), at the three levels of theory. The positive and negative effects on germylene stability are LP_{(F, Cl, Br, and I)} → LP^*_G̈e and σ_(C-Ge) → σ^*_{(C-F, Cl, Br, and I)} interactions, respectively. The results of our calculations show that every singlet germylene with high LP_{(F, Cl, Br, and I)} → LP^*_G̈e interactions has higher electrophilicity. Also, in going from the most electronegative F to the least electronegative I, the nucleophilicity index (N) for germylene increases. Finally, this survey introduces that germylene 4 _s with rather high band gap (ΔE_HOMO-LUMO = 97.19 kcal/mol), nucleophilicity (2.20 eV), and stability (ΔE_s-t = 76.95 kcal/mol) has high proton affinity (171.55 kcal/mol) that can be applied as multidentate ligands and it is hoped that this will prompt experimental attention toward its.

O,N-Heterocyclic germylenes as efficient catalysts for hydroboration and cyanosilylation of benzaldehyde

Novel O,N-heterocyclic germylenes were examined as catalysts for cyanosilylation and hydroboration of benzaldehyde.