Formamide formation on forsterite and Mg(OH)2·H2O
Abstract
Context. Formamide formation in the Universe has been the subject of debate due to its importance as a precursor to amino acids and RNA. Current studies focus on the gas-phase and icy grain formation routes. However, formamide formation on bare silicate surfaces or hydrated Mg-bearing molecular models remains largely unexplored in environments relevant to protoplanetary disks. Aims. This study presents a quantum-chemical investigation of formamide formation on an Mg center and a silicate surface. Mg(OH)2· H2O and the bare (010) forsterite (Mg2SiO4) surface, used as an analog of a bare dust-grain surface, may promote formamide formation via NH2 addition to H2CO. Methods. I employed density functional theory (DFT) to study the addition of NH2 to H2CO with an isolated Mg(OH)2· H2O molecular model and on the forsterite (010) surface. First, I benchmarked various theoretical methodologies. I then examined the ability of Mg(OH)2· H2O and the forsterite (010) surface to promote formamide formation. Finally, for the case with an entrance barrier, I computed unimolecular rate constants and half-lives to assess its kinetic behavior. Results. Mg(OH)2· H2O promotes proton transfer within the NH2-CH2O intermediate via the O-H group coordinated with Mg following NH2 addition to H2CO, whereas on the forsterite, a barrier-less addition pathway is found when NH2 is initially physisorbed close to the formaldehyde center, followed by proton transfer leading to formamide formation. Conclusions. The Mg-bearing model systems considered here can promote rapid proton transfer following NH2 addition to H2CO. For the Mg(OH)2· H2O model, the reaction step from the pre-reactive complex is predicted to occur on nanosecond timescales at temperatures approaching 300 K. The present work provides kinetic data for astrochemical models.
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BibTeX
@misc{campisi2026formamide,
title = {{Formamide formation on forsterite and Mg(OH)$_2\cdot$H$_2$O}},
author = {Dario Campisi},
howpublished = {arXiv},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2611.07172},
eprint = {2611.07172},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2611.07172},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Formamide formation on forsterite and Mg(OH)_2·H_2O
AU - Dario Campisi
PY - 2026
DA - 2026/11/04
PB - arXiv
DO - 10.48550/arxiv.2611.07172
UR - https://arxiv.org/abs/2611.07172
AB - Context. Formamide formation in the Universe has been the subject of debate due to its importance as a precursor to amino acids and RNA. Current studies focus on the gas-phase and icy grain formation routes. However, formamide formation on bare silicate surfaces or hydrated Mg-bearing molecular models remains largely unexplored in environments relevant to protoplanetary disks. Aims. This study presents a quantum-chemical investigation of formamide formation on an Mg center and a silicate surface. Mg(OH)_2· H_2O and the bare (010) forsterite (Mg_2SiO_4) surface, used as an analog of a bare dust-grain surface, may promote formamide formation via NH_2 addition to H_2CO. Methods. I employed density functional theory (DFT) to study the addition of NH_2 to H_2CO with an isolated Mg(OH)_2· H_2O molecular model and on the forsterite (010) surface. First, I benchmarked various theoretical methodologies. I then examined the ability of Mg(OH)_2· H_2O and the forsterite (010) surface to promote formamide formation. Finally, for the case with an entrance barrier, I computed unimolecular rate constants and half-lives to assess its kinetic behavior. Results. Mg(OH)_2· H_2O promotes proton transfer within the NH_2-CH_2O intermediate via the O-H group coordinated with Mg following NH_2 addition to H_2CO, whereas on the forsterite, a barrier-less addition pathway is found when NH_2 is initially physisorbed close to the formaldehyde center, followed by proton transfer leading to formamide formation. Conclusions. The Mg-bearing model systems considered here can promote rapid proton transfer following NH_2 addition to H_2CO. For the Mg(OH)_2· H_2O model, the reaction step from the pre-reactive complex is predicted to occur on nanosecond timescales at temperatures approaching 300 K. The present work provides kinetic data for astrochemical models.
ER -