Ni+ reactions with aminoacetonitrile, a potential prebiological precursor of glycine

TL;DR

This study investigates Ni+ reactions with aminoacetonitrile, revealing dominant HCN loss and the role of a cyclic intermediate, providing insights into prebiotic chemistry relevant to glycine formation.

Contribution

It combines experimental mass spectrometry with DFT calculations to elucidate the reaction mechanisms of Ni+ with aminoacetonitrile, a potential prebiotic precursor of glycine.

Findings

HCN loss is the dominant decomposition pathway.

A cyclic intermediate facilitates HCN and H2CNH loss.

Aminoacetonitrile-Ni+ bond energy is comparable to adenine.

Abstract

The gas-phase reactions between Ni+ (2D5/2) and aminoacetonitrile, a molecule of prebiological interest as possible precursor of glycine, have been investigated by means of mass spectrometry techniques. The mass-analyzed ion kinetic energy (MIKE) spectrum reveals that the adduct ions [NCCH2NH2, Ni+] spontaneously decompose by loosing HCN, H2, and H2CNH, the loss of hydrogen cyanide being clearly dominant. The structures and bonding characteristics of the aminoacetonitrile-Ni+ complexes as well as the different stationary points of the corresponding potential energy surface (PES) have been theoretically studied by density functional theory (DFT) calculations carried out at B3LYP/6-311G(d,p) level. A cyclic intermediate, in which Ni+ is bisligated to the cyano and the amino group, plays an important role in the unimolecular reactivity of these ions, because it is the precursor for the observed losses of HCN and H2CNH. In all mechanisms associated with the loss of H2, the metal acts as hydrogen carrier favoring the formation of the H2 molecule. The estimated bond dissociation energy of aminoacetonitrile-Ni+ complexes (291 kJ mol-1) is larger than those measured for other nitrogen bases such as pyridine or pyrimidine and only slightly smaller than that of adenine.