Coherent D2 rotational tunneling and incoherent D2 dynamics in a solid non-classical RuD2 complex studied by 2H solid state NMR spectroscopy

Abstract

The 2H solid state NMR spectra and relaxation data of a transition metal g2-dideuterium complex, namely T 1 have been measured in the temperature regime from 5.4 to 320 K. trans-[Ru(D 2)Cl(PPh 2 CH 2 CH 2 PPh 2) 2 ]PF 6 , In the sample, coherent and incoherent exchange processes on the time scale of the quadrupolar RuÈD 2 interaction have been found, leading at low temperatures to a tunnel splitting of the 2H NMR spectrum. With increasing temperature a slight increase of the tunnel splitting is observed, in conjunction with a strong increase of the incoherent exchange process, which Ðnally, at temperatures above 20 K, destroys the tunnel splitting and determines the spectral line shape. For the description of the experimental spectra a Liouville formulation of the AlexanderÈBinsch NMR line shape theory, adapted for exchanging deuterons, is employed. It is shown that the whole evaluation of the 2H magnetization takes place in four 2D and two 4D subspaces of the 81D Liouville space, leading to a drastic simpliÐcation of the numerical e †orts in the simulation of the spectral line shapes. The height of the tunnel barrier calculated from the value of the tunnel splitting is 270 meV (6.22 kcal mol~1). The incoherent exchange rates extracted from the spectra and from relaxation data T 1 are analyzed in terms of a Bell tunneling model, with a temperature dependent e †ective potential.

Deuteron NMR Study of the Diverse Mobility of the Ammonium Ions in the Ordered Phase of (ND4)2PtCl4

“…8 suggests for ammonium tetrachloroplatinate, and eventually n t always dropped towards zero. On the other hand, however, incoherent rates raising from 5 kHz at 5:4 K to 2:5 MHz at 103 K were observed for D 2 in a RuD 2 complex [26]. Therefore, we tend to interprete Fig.…”

Orientations of the principal components of electric field gradients and internal motions in dihydrogen ligands from the 2H T1 NMR relaxation data in solution

“…Solid-state 2 H NMR 3 and NMR relaxation measurements in solutions 5,6 and solids 6,7 have also revealed a high D 2 mobility resulting in averaged deuterium quadrupole coupling constants (DQCC). Note, however, that parameters of static quadrupolar tensors at D, reported for similar dihydrogen complexes, 5,6 are in poor agreement for several reasons.…”

“…Second, the static DQCC has reliably been measured thus far for only one dihydrogen complex. 7 In such a situation, an analysis of the 2 H relaxation data T 1 will suffer from many uncertainties. 5,6 Ł Correspondence to: Vladimir I.…”

Efficient Deuterium–Carbon REDOR NMR Spectroscopy

“…One way of representing the efficiency of a REDOR pulse sequence is to calculate numerically, following Eqs. [2] to [8], the powder averaged values of the eigenvalues of : [10] as a function of the angle ␤, with 1 Ͻ 2 Ͻ 3 for each crystallite. Maximization of these parameters can provide a method for optimization of the REDOR pulses.…”