TY - JOUR

T1 - Temperature dependence of the νs(OH) band shape of ortho-Mannich bases in gas phase and liquid xenon solution

AU - Rutkowski, K.

AU - Melikova, S. M.

AU - Koll, A.

PY - 1994/1/1

Y1 - 1994/1/1

N2 - Infrared spectra of the two ortho-Mannich bases 2-(N,N-dimethylaminomethyl)-4-chlorophenol (I) and 2-(N,N-dimethylaminomethyl)-4,6-dichlorophenol (II) with a medium-strong intramolecular hydrogen bond, were measured in a wide frequency (4000-50 cm-1) and temperature (-105°C to +120°C) range in liquid Xe, CCl4 solutions and gas phase. The temperature studies of the first and second spectral moments of the νs(OH) band in liquid Xe within the temperature range from -105 to +30°C allow for the analysis of the νs(OH) mode coupled with the low-frequency vibrations (νl) of the non-linear hydrogen bond. Transitions located at ca. 150, 250 and 340 cm-1 were selected as such νl modes. The effective coupling parameter between high-frequency νs(OH) and low-frequency νl vibrations of the hydrogen bridge was evaluated: b = αssl/ωl {reversed tilde equals} 0.7. Model calculations accounting for the hot and combination transitions give satisfactory reproduction of the gas phase νs(OH) and νs(OD) bands shapes. Both temperature experiments and model calculations predict that even at 0 K the halfwidth of the νs(OH) band can be quite large, viz. ca. 200-400 cm-1.

AB - Infrared spectra of the two ortho-Mannich bases 2-(N,N-dimethylaminomethyl)-4-chlorophenol (I) and 2-(N,N-dimethylaminomethyl)-4,6-dichlorophenol (II) with a medium-strong intramolecular hydrogen bond, were measured in a wide frequency (4000-50 cm-1) and temperature (-105°C to +120°C) range in liquid Xe, CCl4 solutions and gas phase. The temperature studies of the first and second spectral moments of the νs(OH) band in liquid Xe within the temperature range from -105 to +30°C allow for the analysis of the νs(OH) mode coupled with the low-frequency vibrations (νl) of the non-linear hydrogen bond. Transitions located at ca. 150, 250 and 340 cm-1 were selected as such νl modes. The effective coupling parameter between high-frequency νs(OH) and low-frequency νl vibrations of the hydrogen bridge was evaluated: b = αssl/ωl {reversed tilde equals} 0.7. Model calculations accounting for the hot and combination transitions give satisfactory reproduction of the gas phase νs(OH) and νs(OD) bands shapes. Both temperature experiments and model calculations predict that even at 0 K the halfwidth of the νs(OH) band can be quite large, viz. ca. 200-400 cm-1.

KW - Band shape

KW - Hydrogen bonds

KW - Infrared spectrometry

KW - Mannich bases

KW - Temperature dependence

KW - Xenon solutions

UR - http://www.scopus.com/inward/record.url?scp=0028497731&partnerID=8YFLogxK

U2 - 10.1016/0924-2031(94)85016-X

DO - 10.1016/0924-2031(94)85016-X

M3 - Article

AN - SCOPUS:0028497731

VL - 7

SP - 265

EP - 274

JO - Vibrational Spectroscopy

JF - Vibrational Spectroscopy

SN - 0924-2031

IS - 3

ER -