Interstellar branched chain molecules: A theoretical-rotational study

Abstract

Interstellar detection of the straight-chain (n-propyl cyanide, n-C$_{3}$H$_{7}$CN) and branched-chain (i-propyl cyanide, i-C$_{3}$H$_{7}$CN) molecules toward the star-forming region, Sagittarius B2(N2) (Sgr B2(N2)) has attracted attention to study the formation mechanism and chemical evolution of branched carbon-chain molecules. These molecules are the precursors of biologically relevant prebiotic molecules, i.e., amino acids. In this light, we consider n-butyl cyanide and higher-order branched chain molecule, t-butyl cyanide from the C$_{5}$H$_{9}$N isomeric group. Quantum chemical calculations, such as rotational constants, dipole moments and other spectroscopic information will assist to study the chemical evolution and examine the possibility of detecting higher-order branched-chain molecules in high-mass star-forming regions.