Microwave Spectrum, Conformation, Dipole Moment, and Quantum Chemical Calculations of 1-Amino-1-ethenylcyclopropane

Abstract

The microwave spectrum of 1-amino-1-ethenylcyclopropane has been investigated in the 13-40 GHz spectral region at about -45 °C. The prevailing (ap)-rotamer (sp with respect to the cyclopropyl and amino, ap with respect to cyclopropyl and the vinyl group) was assigned. This rotamer is virtually a hybrid of the most stable conformer of unsubstituted ethenylcyclopropane and unsubstituted cyclopropylamine, each in its preferred orientation; it has a symmetry plane (C s symmetry) with the CsN bond and the CdC double bond syn to each another. In this conformation, both of the hydrogen atoms of the amino group may be involved in weak intramolecular hydrogen bonds with the π electrons of the double bond. The dipole moment components and the total dipole moment are (in units of 10 -30 C m): µ a ) 2.00(1), µ b ) 0.89( 14), µ c ) 0.0 (for symmetry reasons), and µ tot ) 2.19(9). Four vibrationally excited states belonging to three different normal modes were assigned and their frequencies determined by relative intensity measurements. The microwave work has been assisted by quantum chemical computations at the elaborate MP2/cc-pVTZ, as well as at the B3LYP/6-31G* levels of theory.

Microwave Spectrum, Conformational Composition, and Intramolecular Hydrogen Bonding of (2-Chloroethyl)amine (ClCH2CH2NH2)

“…6,7 This is also the case for one of the preferred conformers of amino acids exemplified by glycine 8À10 and alanine. 11,12 π-Electrons are involved in a number of cases such as H 2 NCH 2 CHdCH 2 , 13À16 H 2 NCH 2 CH 2 CHdCH 2 , 17 1-amino-1-ethenylcyclopropane, 18 H 2 NCH 2 CtCH, 19 H 2 N-CH 2 CtN, 20,21 H 2 NCH 2 CH 2 CtN, 22 H 2 NCH 2 CH 2 CtCH, 23 and 1-amino-1-ethynylcyclopropane. 24 Pseudo π-electrons 25 are acceptors in (aminomethyl)cyclopropane, 26 while the π-electrons of the phenyl group are active in intramolecular H bonding in, for example, amphetamine.…”

Intramolecular hydrogen bonding in chiral alcohols: The microwave spectrum of the chloropropanols

“…The work of Møllendal and co-workers [2][3][4][5] has demonstrated the true diversity of compounds which are capable of forming hydrogen bonds. Hydrogen donors such as phosphines, selenols, thiols, and even amines have been observed forming weak hydrogen bonds to electron donors such as furan rings, p-bonds of alkenes and cyclopropyl rings.…”

Microwave Spectrum, Conformational Equilibrium, Intramolecular Hydrogen Bonding, Tunneling, and Quantum Chemical Calculations for 1-Ethenylcyclopropan-1-ol

“…These are some of the questions we attempt to answer in this work. It should be added that the present work is a continuation of the studies of intramolecular H bonding made in Oslo …”