Electron spin resonance investigation of H2+, HD+, and D2+ isolated in neon matrices at 2 K

Abstract

Various isotopologues of nature's simplest molecule, namely H(2)(+), HD(+), and D(2)(+), have been isolated in neon matrices at 2 K for the first time and studied by electron spin resonance (ESR). Over many years, hundreds of matrix isolation experiments employing a variety of deposition conditions and ion generation methods have been tried to trap the H(2)(+) cation radical in our laboratory. The molecule has been well characterized in the gas phase and by theoretical methods. The observed magnetic parameters for H(2)(+) in neon at 2 K are: g(∥) ≈ g(⊥) = 2.0022(1); A(iso)(H) = 881(7) MHz; and A(dip)(H) = 33(3) MHz. Reasonable agreement with gas phase values of the isotropic hyperfine interaction (A(iso)) is observed; however, the neon matrix dipolar hyperfine interaction (A(dip)) is noticeably below the gas phase value. The smaller matrix value of A(dip) is attributable to motional averaging of the H(2)(+) radical in the neon matrix trapping site--an occurrence that would prevent the full extent of the hyperfine anisotropy from being measured for a powder pattern type ESR sample.

Electrons Trapped in Solid Neon–Hydrogen Mixtures Below $$1\, \hbox {K}$$

“…Several techniques were used previously for studies of ions and electrons in cryocrystals of hydrogen and its isotopes and rare-gas matrices, including infrared spectroscopy [21], ESR [18,[22][23][24] registration of electron emission current [7] and detection of the cyclotron resonance of emitted electrons [4,25]. Ionization of matrix atoms or molecules was done by irradiation with UV, γ or x rays.…”

“…Ionization of matrix atoms or molecules was done by irradiation with UV, γ or x rays. This process was accompanied by rapid recombination of charged particles and various chemical tunneling reactions leading to a number of exotic ions stabilized in the solids [23,24,26]. In the other technique, the beams of electrons with energies of several keV and higher were directed on the solid samples [7,20].…”

Confirmed by X‐ray Crystallography: The B⋅B One‐Electron σ Bond

“…Yet, as early as 1931 Pauling suggested the existence of one-electron bonds [2] and the simplest of all molecules, the H 2 C + radical cation, is nowadays taken as a role model to explain the detailed physical nature of chemical bonding. [6][7][8][9][10][11][12][13][14][15][16] Specifically, radical anions of the type [R 3 B·BR 3 ]C À ([I]C À , Scheme 1; R = H, OMe) were detected. [6][7][8][9][10][11][12][13][14][15][16] Specifically, radical anions of the type [R 3 B·BR 3 ]C À ([I]C À , Scheme 1; R = H, OMe) were detected.…”

“…[3] Owing to their intrinsically high reactivity, however, most molecules containing one-electron bonds are highly elusive and, in striking contrast to the large body of theoretical knowledge accumulated on such systems in the past decades, the paucity of experimentally characterized examples is remarkable: [4] With two exceptions, [5] experimental evidence has only been gathered for highly sensitive substances by means of elaborate techniques, such as matrix isolation, g-irradiation, H-atom abstraction, or one-electron reduction at low temperatures. [6][7][8][9][10][11][12][13][14][15][16] Specifically, radical anions of the type [R 3 B·BR 3 ]C À ([I]C À , Scheme 1; R = H, OMe) were detected. [13][14][15][16] Moreover, during electrochemical studies on the reduction of Ph 3 B, Mills and DuPont found indications of B·B adduct formation between [Ph 3 B]C À and unreduced Ph 3 B.…”

Confirmed by X‐ray Crystallography: The B⋅B One‐Electron σ Bond

“…[3] Owing to their intrinsically high reactivity, however, most molecules containing one-electron bonds are highly elusive and, in striking contrast to the large body of theoretical knowledge accumulated on such systems in the past decades, the paucity of experimentally characterized examples is remarkable: [4] With two exceptions, [5] experimental evidence has only been gathered for highly sensitive substances by means of elaborate techniques, such as matrix isolation, g-irradiation, H-atom abstraction, or one-electron reduction at low temperatures. [6][7][8][9][10][11][12][13][14][15][16] Specifically, radical anions of the type [R 3 B·BR 3 ]C À ([I]C À , Scheme 1; R = H, OMe) were detected. [13][14][15][16] Moreover, during electrochemical studies on the reduction of Ph 3 B, Mills and DuPont found indications of B·B adduct formation between [Ph 3 B]C À and unreduced Ph 3 B.…”