Phosphine-Stabilized Germylidenylpnictinidenes as Synthetic Equivalents of Heavier Nitrile and Isocyanide in Cycloaddition Reactions with Alkynes

Yuhao He; Chenshu Dai; Dongmin Wang; Jun Zhu; Gengwen Tan

doi:10.1021/jacs.2c00305

Phosphine-Stabilized Germylidenylpnictinidenes as Synthetic Equivalents of Heavier Nitrile and Isocyanide in Cycloaddition Reactions with Alkynes

J Am Chem Soc. 2022 Mar 23;144(11):5126-5135. doi: 10.1021/jacs.2c00305. Epub 2022 Mar 9.

Authors

Yuhao He¹, Chenshu Dai², Dongmin Wang¹, Jun Zhu², Gengwen Tan¹

Affiliations

¹ College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, China.
² State Key Laboratory of Physical Chemistry of Solid Surfaces, Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China.

PMID: 35263091
DOI: 10.1021/jacs.2c00305

Abstract

The reactions of chlorogermylene M^sFluind^tBu-GeCl 1, supported by a sterically encumbered hydrindacene ligand M^sFluind^tBu, with NaPCO(dioxane)_2.5 and NaAsCO(18-c-6) in the presence of trimethylphosphine afforded trimethylphosphine-stabilized germylidenyl-phosphinidene 2 and -arsinidene 3, respectively. Structural and computational investigations reveal that the Ge-E' bond (E' = P and As) features a multiple-bond character. 2 and 3 exhibit diverse reactivity toward trimethylsilylacetylene and 4-tetrabutylphenylacetylene. Specifically, 2 underwent cycloadditions with both alkynes affording the first six-membered aromatic phosphagermabenzen-1-ylidenes 4 and 5, respectively, through the heavier isocyanide intermediate M^sFluind^tBu-PGe. In contrast, 3 could serve as a synthetic equivalent of heavier isocyanides and nitriles when treated with trimethylsilylacetylene and 4-tetrabutylphenylacetylene yielding arsagermene 6 and arsolylgermylene 7, respectively. The reaction mechanisms for the cycloadditions were investigated through density functional theory calculations. The reactivity studies highlight the potential of 2 and 3 in accessing heavy main-group element-containing heterocycles.