One-Pot Synthesis of Heavier Group 14 N-Heterocyclic Carbene Using Organosilicon Reductant

Abstract

Syntheses of heavier Group 14 analogues of "Arduengo-type" N-heterocyclic carbene majorly involved the use of conventional alkali metal-based reducing agents under harsh reaction conditions. The accompanied reductant-derived metal salts and chances of over-reduced impurities often led to isolation difficulties in this multi-step process. In order to overcome these shortcomings, we have used 1,4-bis-(trimethylsilyl)-1,4-diaza-2,5-cyclohexadiene as a milder reducing agent for the preparation of N-heterocyclic germylenes (NHGe) and stannylenes (NHSn). The reaction occurs in a single step with moderate yields from the mixture of N-substituted 1,4-diaza-1,3-butadiene, E(II) (E(II) = GeCl 2 ·dioxane, SnCl 2 ) and the organosilicon reductant. The volatile byproducts trimethylsilyl chloride and pyrazine could be removed readily under vacuum. No significant over reduction was observed in this process. However, N-heterocyclic silylene (NHSi) could not be synthesized using an even stronger organosilicon reductant under thermal and photochemical conditions.

Coherent Solution‐phase Synthesis of a Germanium‐Graphitic Nanocomposite and Its Evaluation for Lithium‐Ion Battery Anodes: Non‐innocent Role of the Mashima Reagent

“…Recently, this reduction method has been applied to main group compounds such as dibismuthene and distibene . Our group has reported the one‐pot syntheses of N ‐heterocyclic germylene and stannylene using 1,4‐bis‐(trimethylsilyl)‐1,4‐diaza‐2,5‐cyclohexadiene as the reductant . The reaction occurs in a single step and the volatile byproducts trimethylsilylchloride and pyrazine could be easily removed under vacuum yielding the heavier carbenes .…”

“…Our group has reported the one‐pot syntheses of N ‐heterocyclic germylene and stannylene using 1,4‐bis‐(trimethylsilyl)‐1,4‐diaza‐2,5‐cyclohexadiene as the reductant . The reaction occurs in a single step and the volatile byproducts trimethylsilylchloride and pyrazine could be easily removed under vacuum yielding the heavier carbenes . This organosilicon reagent proved to be crucial for an elusive reductive cyclization step from bis(α‐iminopyridine) stabilized bis(chlorogermyliumylidene) …”

“…[6] The reaction occurs in a single step and the volatile byproducts trimethylsilylchloride and pyrazine could be easily removed under vacuum yielding the heavier carbenes. [6] This organosilicon reagent proved to be crucial for an elusive reductive cyclization step from bis(α-iminopyridine) stabilized bis(chlorogermyliumylidene). [7] In the nano regime, metal (0) particles have been achieved using this salt-free reduction method for both transition metal chlorides and also main-group chlorides (Ga, In, Sb and Bi).…”

Synthesis and Thermal Investigations of Eleven-Membered Ring Systems Containing One of the Heavier Group 14 Element Atoms Si, Ge, and Sn

“…Although heterocyclic compounds containing group 14 elements are very advanced and can be designed using several synthetic approaches [12,13] they fall short of a detailed materials characterization. An important aspect to consider is the influence of the group 14 elements on the structural properties of the investigated molecule.…”

Coordination Chemistry of Silicon

“…XRD analysis unveiled the structures of these compounds, and hydrogen-bond interactions were discussed. The group of Majundar describes the facile one-pot synthesis of N-heterocyclic germylene and stannylene using 1,4-bis(trimethylsilyl)-1,4-diaza-2,5-cyclohexadiene as a mild organosilicon reductant [22]. In this reaction, the volatile byproducts trimethylsilyl chloride and pyrazine can easily be removed under vacuum, and significant over reduction was not observed.…”