Temperature Dependence of 2H Nuclear Quadrupole Interaction in Very Short Hydrogen Bonds in Some Organic Acidic Salt Crystals

نویسندگان

  • K. Miyakubo
  • N. Nakamura
چکیده

The H nuclear quadrupole interaction parameters, 2 and , are closely related to the shape of the potential energy surface at hydrogen bonds and depend sensitively on their geometry. We measured the temperature dependence of the H NMR spectra of the crystalline acidic salts KDCO3, KD acetylenedicarboxylate, RbD acetylenedicarboxylate, and KD maleate, which contain very short O-D O type hydrogen bonds. The temperature coefficient decreases with increase in the O O distance in the hydrogen bond. Ab inito molecular orbital calculations of the electric field gradient tensor based on the temperature dependent structure of each crystal indicate that thermal expansion of the hydrogen bond geometry is not responsible for this tendency. Ab initio calculations also predict that a fictitious off center shift of the hydrogen position in a symmetric hydrogen bond causes very high 2 values. This suggests that low energy vibrational excitation may be responsible for large positive d ( 2 )/d values in symmetric hydrogen bonds.

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

Study of Dehydrogenation of Pressure-induced NaBH4 Structures Using Calculated NQCC Parameters

Nuclear quadrupole resonance (NQR) spectroscopy is an accurate method for determination of electric charge distribution around quadrupolar nuclei. Using ab initio computational methods, it is possible to calculate the Nuclear Quadrupole Coupling Constants (NQCCs) with high accuracy and obtain the useful structural information by using these parameters. Sodium Borohydride, NaBH4, is a metal hydr...

متن کامل

Comparison of metal additives and Boron atom on MgH2 absorbing-desorbing characteristics using calculated NQCCs

Using ab initio calculations, the hydrogen desorption from Magnesium hydride (MgH2) was studied. We presented the calculated nuclear quadrupole coupling constants (NQCCs) of hydrogen atom in various systems of MgH2. The effect of interactions of some metal atoms as well as Boron atom with MgH2 host matrix; (MgH2+M) nanostructures (M=Al, Ti, V, Fe, Ni ...

متن کامل

Comparison of metal additives and Boron atom on MgH2 absorbing-desorbing characteristics using calculated NQCCs

Using ab initio calculations, the hydrogen desorption from Magnesium hydride (MgH2) was studied. We presented the calculated nuclear quadrupole coupling constants (NQCCs) of hydrogen atom in various systems of MgH2. The effect of interactions of some metal atoms as well as Boron atom with MgH2 host matrix; (MgH2+M) nanostructures (M=Al, Ti, V, Fe, Ni ...

متن کامل

Temperature dependent deuterium quadrupole coupling constants of short hydrogen bonds

Very short hydrogen bonds universally show large positive dependences of the deuterium NMR quadrupolar coupling constant with temperature. We present temperature dependent NMR data for eight such systems, with O/O distances of between 238 and 250 pm, and show we can model the temperature dependences by density functional methods, as long as proper attention is paid to intermolecular effects and...

متن کامل

Terahertz Vibrations and Hydrogen-Bonded Networks in Crystals

The development of terahertz technology in the last few decades has made it possible to obtain a clear terahertz (THz) spectrum. THz vibrations clearly show the formation of weak bonds in crystals. The simultaneous progress in the code of first-principles calculations treating noncovalent interactions has established the position of THz spectroscopy as a powerful tool for detecting the weak bon...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

عنوان ژورنال:

دوره   شماره 

صفحات  -

تاریخ انتشار 2002