Low Valent N‐Coordinated Cations and Dications of Heavier Group 14 Elements: Lewis Acids or Bases?

Abstract

Low‐valent N‐coordinated cations and dications of heavier group 14 elements are of great interest in recent years. Their unique electronic structure gives them an ambiphilic character, as they contain both a lone electron pair and an empty p‐orbital on the central metal atom. Thanks to their nucleophilic character, these compounds can act as ligands in transition metal chemistry, and conversely, their electrophilic character allows them to interact with a wide range of organic substrates and thus replace catalysts based on transition metal complexes in many chemical transformations. The aim of this article is to summarize the synthesis of N‐coordinated ionic compounds of heavier group 14 elements with their subsequent reactivity towards various nucleophiles and electrophiles.

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

“…The chemistry of stannyliumylidenes is significantly less explored compared to their Ge( ii ) and Sn( ii ) analogs, which is attributed to the large energy difference between their s- and p-orbitals, making them less reactive. 149 Unlike neutral stannylenes, reports on the hydroboration of carbonyl compounds by the Sn( ii ) cation are rare. Nagendran and group synthesized Sn62 and used it as a catalyst for the hydroboration of carbonyl compounds (0.025 mol% for aldehyde and 0.25 for ketone) (Scheme 147).…”

Tetryliumylidene ions in synthesis and catalysis

“…29,30 Following these discoveries, researchers have successfully isolated a range of tetryliumylidene ions. 31 This was made possible by employing sterically demanding ligands for kinetic stabilisation, including bulky amide groups, 32 β-diketiminato, 33 aminotroponiminate, 34 and cyclophane groups. 35 Alternatively, Lewis basic ligands, such as carbenes, 36,37 imines, 38 or weakly coordinating arenes, 39 have been utilised for the enhancement of the thermodynamic stability.…”