Nuclear Magnetic Resonance Spectroscopy

BY B.E. MANN

1 Introduction

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. Reviews which are of direct relevance to a section of this report are included in the beginning of that section rather than here. Papers where only 1H, 2H, 13C, 19F, and/or 31P NMR spectroscopy is used are only included when they make a non-routine contribution, but complete coverage of relevant papers is still attempted where nuclei other than these are involved. In view of the greater restrictions on space, and the ever growing number of publications, many more papers in marginal areas have been omitted. This is especially the case in the sections on solid-state NMR spectroscopy, silicon and phosphorus.

Several reviews have been published which are relevant to this review: 'Understanding NMR chemical shifts', 'Two-dimensional correlation spectroscopy by scalar couplings: A walk through the Periodic Table', 'In vivo31P and 23Na NMR spectroscopy and imaging', 'Application to the calcium-binding regulatory enzyme, calmodulin. A quantitative study on metalloenzymes', which contains 43Ca and 113Cd NMR spectroscopy, 'The correlation between transition metal NMR chemical shifts and the stability of coordination compounds', 'Transition metal complexes containing hydrazine and substituted hydrazines', which contains 15N and 103Rh NMR spectra, 'Coordination chemistry of metallodrugs: insights into biological speciation from NMR spectroscopy', which contains 15N, 109Ag, and 195Pt NMR spectra, '1H-31P pulsed field gradient heteronuclear multiple-bond correlation (PFG-HMBC) spectroscopy', which contains spectra of compounds such as [(η5-C5H5)Ni(µ-H)(µ-CO) -W(η5-C5H5)2], 'An assessment of the parameters relevant to the subdivision of σ and π electronic effects in M–P bonds', which contains δ(13CO) and 1J(M–P), NMR in the study of inorganic complexes of the noble metals', 'Metallothio-neins', which contains 113Cd NMR spectra, 'The chemistry of metal complexes with selenolate and tellurolate ligands', which contains 77Se and 125Te NMR spectra, 'NMR spectroscopy (of halides and pseudo-halides)', 'Mesoionic compounds - structure and NMR spectral parameters', which contains 14N, 15N, 17O, and 77Se NMR spectra, 'Molecular architecture of bimetallic active centres and their bifunctional catalysis', which contains 129Xe NMR spectra, 'Preparation of samples for analysis of wastewaters by NMR spectroscopy', 'Applications of nuclear magnetic resonance in the study of magnetic materials', and 'Application of NMR methods to catalysis'.

A number of papers have been published which are too broadly based to fit into a later section and are included here. A three-pulse sequence has been described which generates detectable three quantum coherence in I = 3/2 and 3 and five quantum coherence in I = 5/2 spin systems. The variation of the NMR shielding with the Periodic Table has been examined. The spin-lattice relaxation times of 1H2 and 2H 2 have been determined in aqueous solutions. The theory of thermal effects in the nuclear magnetic resonance spectra of metal hydrides undergoing quantum mechanical exchange has been developed. A theoretical study of the origin of 1H chemical shifts in low-valent transition metal hydrides has been reported. A theoretical study of 13C and 17O NMR shielding tensors in transition metal carbonyls based on density functional theory and gauge-including atomic orbitals has been carried out. High-pressure NMR spectroscopy has been used to study metal complexes in supercritical fluids. The molecular dynamics in [M(OMe)6], M = U, Mo, W, Sb, have been analysed using 1H T1 measurements. The O NMR chemical shifts of several previously characterized mono- and diperoxo complexes of vanadium (V), molybdenum (VI), tungsten(VI) and titanium (IV) have been measured. Monoperoxo complexes exhibit 17O chemical shifts of δ 500–660, while those of diperoxo complexes fall in the range δ 350–460. The lineshapes in solution of an I = 1/2 nucleus with scalar coupling to one quadrupolar nucleus which is subject to random-field relaxation have been calculated using a relaxation matrix treatment and applied to 59C coupled to Co. The analysis of the signal to noise ratios for noise excitation of quadrupolar nuclear spins, e.g., Cl, has been performed in zero field. The shift of the NMR frequency under sample spinning has been examined and applied to 1H and 119Sn in liquid samples.

2 Stereochemistry

Complexes of Groups 1 and 2. – Four reviews have appeared entitled 'In vivo MRS measurement of lithium levels in brain', which includes Li NMR spectra,'Use of 23Na NMR to study sodium-macromolecule interactions', 'Nuclear magnetic resonance analyses of Grignard reagents', and 'Physical methods for studying the biological chemistry of magnesium', which contains 25Mg NMR spectroscopy.

Pulsed field gradient 'inverse' HOESY has been applied to the isotope pair 1H, 7Li in Bun Li. IGAIM 13C and 1H chemical shifts have been calculated for organolithium compounds. The formation of [Li2((Me3Si)PhCC-(SiMe3) C(SiMe3)CPh(SiMe3)}] has been demonstrated using 1J(13C6Li) = 2.7 Hz, and by using two-dimensional 6Li-29Si HMQC which detected 2J (29Si6Li) and 3J(29Si6Li). 1J(13C6Li) = 17.6 Hz has been observed in Li enriched [LiC=C(SiMe3)CMe2]. The nature of the lithium counter cations in lithiated (E)-1-(RS)-but-2-ene has been investigated by 6Li-1H HOESY NMR spectroscopy. 1H-7Li HOESY NMR spectroscopy has been used to show short contacts between the peri hydrogen and lithium in [(ArOLi)m(BuLi)n]. NMR data have also been reported for [(2-Ethexyl)M], (M = Li, Na; 7Li, 23Na), [But2SiFCLi(GeMe3)2·THF], (7Li, 29Si),[LiOCBut2C=C(Li) CMe2], (7Li), [(η3-ButMe2 SiCHCHCHSiButMe)Li(tmeda)], (7Li, 29Si), [Li{η5-C5(CH2Ph)5}][Al {η5-C5(CH2Ph)5}2], (7Li, 27Al), (1), (7Li), [(µ-Li)3{µ-C6H3-2,6-(NMe2) 2}3], (6Li), [LiC6H3 -2,6-(C6H3Pri2-2,6)2], (7Li), [Cs2(Me2SiNHMe2SiN) 2·3(THF)], (29Si, 133Cs), [Ar2HGeLi], (7Li), and [Me3Si)3GeLi(THF)3], (7Li).

Ab initio molecular orbital calculations of 1J(15N 6Li) have been carried out for lithium amide monomers and oligomers, and mixed aggregates with LiCL. There is a linear correlation between δ (7Li) and the...