Complexes of Formaldehyde and α-Dicarbonyls with Hydroxylamine: FTIR Matrix Isolation and Theoretical Study

Abstract

The interactions of formaldehyde (FA), glyoxal (Gly) and methylglyoxal (MGly) with hydroxylamine (HA) isolated in solid argon and nitrogen were studied using FTIR spectroscopy and ab initio methods. The spectra analysis indicates the formation of two types of hydrogen-bonded complexes between carbonyl and hydroxylamine in the studied matrices. The cyclic planar complexes are stabilized by O-H⋯O(C), and C-H⋯N interactions and the nonplanar complexes are stabilized by O-H⋯O(C) bond. Formaldehyde was found to form with hydroxylamine, the cyclic planar complex and methylglyoxal, the nonplanar one in both argon and nitrogen matrices. In turn, glyoxal forms with hydroxylamine the most stable nonplanar complex in solid argon, whereas in solid nitrogen, both types of the complex are formed.

Keywords: carbonyls; computational chemistry; hydrogen bond; hydroxylamine; matrix isolation; vibrational spectroscopy.

Figure 1

The optimized structures of the HCHO–NH₂OH complexes, I_FH–V_FH. The ∆E_CP(ZPE)-binding energies in kJ mol⁻¹ are given in parentheses. The intermolecular distances are given in Å.

Figure 2

The spectra of the HCHO/Ar (a), NH₂OH/Ar (b) and HCHO/NH₂OH/Ar (c) matrices recorded after matrix deposition at 11 K. The bands of the HCHO–NH₂OH complex are marked by the arrows.

Figure 3

The optimized structures of the CHOCHO–NH₂OH complexes, I_GH–IV_GH. The ∆E^CP (ZPE)-binding energies in kJ mol⁻¹ are given in parentheses. The intermolecular distances are given in Å.

Figure 4

The spectra of the CHOCHO/Ar (a), NH₂OH/Ar (b) and CHOCHO/NH₂OH/Ar (c) matrices recorded after matrix deposition at 11 K. The bands of the CHOCHO–NH₂OH complex are indicated by the arrows.

Figure 5

The spectra of the CHOCHO/N₂ (a), NH₂OH/N₂ (b) and CHOCHO/NH₂OH/N₂ (c) matrices recorded after matrix deposition at 11 K. The bands of CHOCHO–NH₂OH complexes are indicated by the arrows. Solid and dashed arrows correspond to the III_GH and I_GH structures, respectively.

Figure 6

The optimized structures of the CH₃COCHO–NH₂OH complexes, I_MHk–IV_MHk and I_MHa–IV_MHa. The intermolecular distances are given in Å. The ∆E^CP(ZPE)-binding energies in kJ mol⁻¹ are given in parentheses.

Figure 7

The spectra of the CH₃COCHO/Ar (a), NH₂OH/Ar (b) and CH₃COCHO/NH₂OH/Ar (c) matrices recorded after matrix deposition at 11 K. The bands of the CH₃COCHO–NH₂OH complex are indicated by the arrows.

Figure 8

The spectra of the CH₃COCHO/N₂ (a), NH₂OH/N₂ (b) and CH₃COCHO/NH₂OH/N₂ (c) matrices recorded after matrix deposition at 11 K. The bands of CH₃COCHO–NH₂OH complex are indicated by the arrows.