Isolation and Reactivity of Stannylenoids Stabilized by Amido/Imino Ligands

Reactivity of NHI-Stabilized Heavier Tetrylenes towards CO2 and N2 O

A heteroleptic amino(imino)stannylene (TMS2 N)(It BuN)Sn: (TMS=trimethylsilyl, It Bu=C[(N-t Bu)CH]2 ) as well as two homoleptic NHI-stabilized tetrylenes, (It BuN)2 E: (NHI=N-heterocyclic imine, E=Ge, Sn) are presented. VT-NMR investigations of (It BuN)2 Sn: (2) reveal an equilibrium between the monomeric stannylene at room temperature and the dimeric form at -80 °C as well as in the solid state. Upon reaction of the homoleptic tetrylenes with CO2 , both compounds insert two equivalents of CO2 , however differing bonding modes can be observed. (It BuN)2 Sn: (2) inserts one equivalent of CO2 into each Sn-N bond, giving carbamato groups coordinated κ2 O,O' to the metal center. With (It BuN)2 Ge: (3), the Ge-N bonds stay intact upon activation, being bridged by one molecule of CO2 respectively, forming 4-membered rings. Furthermore, the reactivity of 2 towards N2 O was investigated, resulting in partial oxidation to form stannylene dimer [((It BuN)3 SnO)(It BuN)Sn:]2 (6).

Synthesis and isolation of a cyclic bis-vinyl germylene via a diazoolefin adduct of germylene dichloride

Since the successful isolation of various stable diazoolefins, an array of complexes containing these promising ligands have been synthesized. We herein report the synthesis, characterization, and structures of neutral group 14 diazoolefin complexes and the subsequent transformation into a new cyclic bis-vinyl germylene.

Insight into the addition reactions of stannylenoid H2SnLiF with ethylene

CONTEXT

Tetrylenoids, R₂EXM (E = Si, Ge, and Sn; X = electronegative group; M = alkali metal), have electrophilic and nucleophilic properties just like carbenoid. As the products of carbenoid compounds with olefins, the cyclopropane fraction has been found to be biologically active in many natural and artificial compounds. Can carbenoid analogues of stannylenoid facilitate similar cyclopropanation reactions?

METHODS

Addition reaction of the stannylenoid compound H₂SnLiF with ethylene was investigated using density function theory (DFT) at the M062X/def2-TZVP level. The single-point energy calculations were performed on the basis of QCISD/def2-TZVP level.

RESULTS

Two possible pathways were found for the addition reaction of H₂SnLiF (R1) with ethylene (R2). The most favorable path is the two successive reactions of H₂SnLiF and ethylene through the ternary ring product c-H₂Sn(CH₂)₂ (P1) and then the formation of the five-membered ring product (P2). Solvation-related studies have shown that addition reactions are more likely to occur in the presence of THF solvents. This work provides theoretical support for the reactions of stannylenoid with olefins.

An Air-Stable "Masked" Bis(imino)carbene: A Carbon-Based Dual Ambiphile

Carbenes, once considered laboratory curiosities, now serve as powerful tools in the chemical and material sciences. To date, all stable singlet carbenes are single-site ambiphiles. Here we describe the synthesis of a carbene which is a carbon-based dual ambiphile (both single-site and dual-site). The key is to employ imino substituents derived from a cyclic (alkyl)(amino)carbene (CAAC), which imparts a 1,3-dipolar character to the carbene. Its dual ambiphilic nature is consistent with the ability to activate simple organic molecules in both 1,1- and 1,3-fashion. Furthermore, its 1,3-ambiphilicity facilitates an unprecedented reversible intramolecular dearomative [3 + 2] cycloaddition with a proximal arene substituent, giving the carbene the ability to "mask" itself as an air-stable cycloadduct. We perceive that the concept of dual ambiphilicity opens a new dimension for future carbene chemistry, expanding the repertoire of applications beyond that known for classical single-site ambiphilic carbenes.