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Spectroscopic Evidence for Aminomethylene (H−C̈−NH 2 )—The Simplest Amino Carbene
Author(s) -
Eckhardt André K.,
Schreiner Peter R.
Publication year - 2018
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201800679
Subject(s) - flash vacuum pyrolysis , carbene , matrix isolation , chemistry , singlet state , matrix (chemical analysis) , ab initio , pyrolysis , argon , excited state , organic chemistry , physics , atomic physics , catalysis , chromatography
Although N‐heterocyclic carbenes have been well‐studied, the simplest aminocarbene, aminomethylene H−C̈−NH 2 , has not been spectroscopically identified to date. Herein we report the gas‐phase preparation of aminomethylene by high‐vacuum flash pyrolysis of cyclopropylamine and subsequent trapping of the pyrolysate in an inert argon matrix at 12 K. Aminomethylene was characterized by matching matrix IR and UV/Vis spectroscopic data with ab initio coupled cluster computations. After UV irradiation of the matrix aminomethylene rearranges to its isomer methanimine (formaldimine) H 2 C=NH. Based on our experimental results and computations aminomethylene has a singlet ground state with a reaction barrier of almost 46 kcal mol −1 to methanimine so that H‐tunneling is excluded.