NMR Spectroscopy in the Solid State

This chapter consists of three main parts Motion in Solids , Structure of Solids and Molecules Sorbed Onto Solids . There is an Appendix at the end of the chapter where reference numbers of papers involving the use of the less common nuclei are collected. 

Following the criteria established in earlier volumes, only books and reviews directly relevant to this chapter are included, and the reader who requires a complete list is referred to the Specialist Periodical Reports Nuclear Magnetic Resonance , where a complete list of books and reviews is given. 

An lUPAC recommendation has been published which is of relevance in this chapter. NMR nomenclature. Nuclear spin properties and conventions for chemical shifts - (lUPAC recommendations 2001) recommends a unified scale for reporting the NMR chemical shifts of nuclei relative to the resonance of TMS.2 

Spectroscopic Properties of Inorganic and Organometallic Compounds, Volume 35 

Minami, A. Hayashi and M. Tatsumisago, Solid State Ionics, 2000,136,1015. 

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For the 1,4-dithiane skeleton, two S-alkyl-l,4-dithianium salts 72 and 73 were studied by variable temperature NMR spectroscopy in the solid state (13C CP-MAS) (99JMS93) line shape variations were attributed to the conformational motion of the six-membered ring (cf. Scheme 26). Also, the vibrational frequencies of the 1,4-dithiane derivative were analysed in detail it was corroborated that the molecule exists in the C2h configuration similar to the chair form of cyclohexane (99SA(A)121). 

In the case of NMR spectroscopy in the solid state, T is the rigorous liou-villian iL where... 

For both NMR spectroscopy in the solid state and EPR spectroscopy in the liquid state it is possible to determine a fairly large number of parameters s . After solving this first problem, one has then to determine the absorption lineshapes in terms of this information. The main aim of this chapter is to show the algorithm of Chapter III at work. However, before launching into this illustration, we would like to mention the alternative approaches currently being used in the field of magnetic resonance. 

Three solid state wide-line studies of the Yb nucleus have appeared [40-42]. More recently, a static powder and a MAS study have been reported for RbYbl3 [43]. Two CP MAS reports have also recently appeared [44-45]. These large csa values do not constitute any obstacle for the routine observation of Yb NMR spectroscopy in the solid state. 

A combination of methods which include MM2 and MNDO calculations, NMR spectroscopy in the solid state (CPMAS) and in solution ( H, C, LSR, chiral solvents, and NOE experiments), DSC and x-ray powder diffraction, has been used to study the conformation of tris(pyrazol-l-yl)methanes (94) and ethanes <89T7805>. It has been shown that tris(3,5-dimethylpyrazol-l-yl)me-thane exists in two isolable isomers, the abb and the bbb (a or b depending on the orientation of the lone pair with regard to the substituent, H or CHj, on the sp carbon), whose interconversion by melting, crystallization, and sublimation has been studied. 

The great power of NMR compared with other spectroscopic techniques is the ability to study both the frequency and geometry of molecular rearrangements in the solid state. It is true to say that there have been few studies of molecular motion in poly(imide)s using NMR spectroscopy. The main reason for this has been the previously limited temperature range of commercial CPMAS probes. Therefore, future work in poly(imide)s is expected to exploit the ground-breaking efforts of other workers in the field of multidimensional NMR spectroscopy in the solid state [3]. 

Related studies have made use of 2H NMR spectroscopy in the solid state. The theoretical foundation for the study of dynamics in dihydrogen complexes was developed by Buntkowsky and coworkers.124 Solid-state 2H NMR spectroscopy has been used to study the dynamics of bound D2 in tntns- Ru( D2)CI(dppe)2 PI>, where evidence was found for coherent rotational tunneling, with a barrier of 6.2kcal/ mol.125 In more recent work, solid-state 2H NMR spectroscopy has been used to determine the structure and dynamics of several dihydrogen Ru complexes.126... 

Most metals have quadrupolar nuclei. For these, Jp coupling constants are measured by CP/MAS P-NMR spectroscopy in the solid state. This technique is not within the scope of this book. We will limit ourselves to the dipolar nuclei Rh and... 

Similarly, a C3 symmetric wefa-trimethoxy substituted hexaphenylbenzene precursor 95 with three alternating methoxy and alkyl (dodecyl) substituents was synthesized and planarized by cyclodehydrogenation (Scheme 22) [55]. A strong aggregation in solution was also observed (by NMR spectroscopy). In the solid state a complex helical superstructure was formed due to the influence of the methoxy groups in meta position as well as intermolecular interactions. After deposition on a surface, microfibers were obtained. 

I. SchneU, H.W. Spiess, High-resolution H NMR spectroscopy in the solid state very st sample rotation and multiple-quantum coherences, J. Magn. Reson. 151 (2001) 153-227. 

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