NMR Spectroscopy in the Liquid and Gas Phase

BY B.E. MANN

1 Introduction

In order to reduce the length of individual chapters, this report on 'NMR Spectroscopy' has been divided into two chapters: 'NMR Spectroscopy in the Liquid and Gas Phase' and 'NMR Spectroscopy in the Solid State'. 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. 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.

Several reviews have been published which are relevant to this review: 'High resolution NMR as a probe of molecular structure, dynamics and diffusion', which contains 6Li NMR spectra, 'Characterization method of the isomers of tetra-substituted metal phthalocyanines by 1H NMR', 'Perspectives in inorganic structural biology: solution structures of metalloproteins', 'Electro-negativity and chemical hardness of organoelement groups' and 'Calculating the NMR properties of minerals, glasses and aqueous species'.

Two IUPAC recommendations have been published which are of relevance in this chapter. 'NMR nomenclature. Nuclear spin properties and conventions for chemical shifts – (IUPAC recommendations 2001)' recommends a unified scale for reporting the NMR chemical shifts of nuclei relative to the 1H resonance of TMS. 'Guidelines for the representation of pulse sequences for solution-state nuclear magnetic resonance spectroscopy – (IUPAC recommendations 2001)' have also been published.

A number of papers have been published which are too broadly based to fit into a later section and are included here. Quantum chemical B3LYP/cc-pvqz computation of ground-state structures and properties of small molecules with atoms of Z ≤ 18 has included NMR chemical shifts. The temperature- and pressure-dependence of the self-diffusion and spin-lattice relaxation in fluid hydrogen and deuterium has been determined. The effects of temperature and isotopic substitution on H–H distances in elongated transition metal dihydrogen complexes have been reported. The structural and dynamic properties of tetrahydroborate complexes have been investigated. The dynamics of I = 3/2 nuclei, including 23Na, under spin-locking conditions in an ordered environment, have been determined. The line widths of 14N, 53Cr, 59Co, 91Zr and 95Mo of coordination complexes in supercritical and liquefied gases have been shown to be significantly less than in conventional solvents. The 29Si chemical shifts of silylene, : [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII], complexes of Cr, Mo, W, Fe, Ru and Ni complexes have been reported. The perturbation of 13C chemical shifts of metal complexes of 3-oxido-2-Ph-propenal by 2H has been determined and positive shifts have been found. The measurement of aromaticity by NMR spectroscopy has been investigated for compounds including organometallic compounds. 55Mn, 63Cu, 95Mo, 125Te and 195Pt NMR spectra have been reported for complexes of 1,2-(MeTeCH2)2C6H4. Cross-correlation effects in NMR spectra of a I = 1/2 nucleus scalar coupled to a I ≥ 1 nucleus have been studied for pairs of nuclei such as 13C-11B and 31P-Co. Diffusion data from pulsed-field gradient spin-echo methods have been shown to be qualitatively useful in the investigation of problems involving unknown molecular aggregation and/or the nature of inter-ionic interactions in metal complexes.

2 Stereochemistry

This section is subdivided into eleven parts which contain NMR information about Groups 1 and 2 and transition metal complexes presented by Groups according to the Periodic Table. Within each Group, classification is by ligand type.

2.1 Complexes of Groups 1 and 2. – The 6Li NMR spectrum of [CyCH=CHCH{NAr(COBut)}6Li·(-)sparteine] shows two signals due to chirality. 7Li, 13C and 14N NMR spectra of the lithiated 1,2,2,5,5-Me5-3-imidazoline 3-oxide have been discussed. The 7Li NMR spectrum of [[FORMULA NOT REPRODUCIBLE IN ASCII]] shows six signals. 7Li NMR chemical shifts have been calculated for lithiated corannulene rings in order to analyse the aromaticity. 1J(13C7Li) and the coupling pattern of the lithiated carbon of [(1-Me2N-8-naphthyl)Li(THF)] 2 have demonstrated that the compound is a dimer. Si Chemical shifts have been calculated for amino-functionalized silyl lithium compounds such as [Ph2SiLi(NEt2)]. NMR data have also been reported for [LiBH4}HN(CH2Ph)2}2], (7Li, 11B), BunLi complexes with anisyl fencholates [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII].

One- and two-dimensional 6Li and 15N NMR spectroscopy has been used to study [LiNPri2] solvated by oxetane, THF, Et2O and HNPri2. NMR data have also been reported for [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII].

Dynamic nuclear polarization of water protons has been used to measure the relaxation time of 7Li at very low magnetic field. NMR data have also been reported for [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII], Li salts in poly(ethylene oxide)-poly(methyl methacrylate), (7Li), Li salts in poly(acrylonitrile), (7Li) and Li salts in graphite, (7Li).

23Na NMR shieldings and quadrupole coupling constants have been calculated for Na+ complexes with crown ethers. 1H, 13C and 23Na NMR spectroscopy has been used to study the solution structure and complexation behaviour of some bis(benzo crown ether)s. The states of water and sodium ions in poly(N-Pri-acrylamide) gel have been studied using 1H and 23Na NMR spectroscopy. 2H, 19F and 23Na NMR spectroscopy has been used to study dilute lamellar liquid crystals. The accumulation of Na+ in human red cells has been investigated using 23Na NMR spectroscopy. Intracellular Na+ in the presence of Dy tripolyphosphate in HeLa cells has been monitored using 23Na NMR spectroscopy. Intra- and extra-cellular Na+ ions have been investigated using [Tm(DOTP)] 5- as a 23Na shift reagent. The effects of 1,3-(ClCH2CH2)2-1-nitrosourea on 23Na and 31P NMR signals of subcutaneously implanted 9L glioma have been investigated. The measurement of 23Na-1H NMR spectroscopy in mice has been described. 23Na and 31P NMR spectroscopy has been used to look at Na+, K+, Cl- co-transport. 23Na MRI has been applied to determining myocardial viability. The 23Na chemical shift of NaXe has been reported. NMR data have also been reported for [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII], (29Si).

The use of a rubidium–xenon polarization unit has enabled the measurement of both 85Rb and 129Xe polarization. Three-dimensional 87Rb NMR imaging has been applied to pig hearts. 133Cs chemical shifts have been studied in binary melts of [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII]. J(133Cs19F) = 54.9 Hz has been observed in the Cs+ complex of (4). 133Cs NMR spectra of the liquid crystalline medium have been examined for NMR quantum computing. NMR data have also been reported for potassium hydrido iodide, (39K).

13C T1 values of the carboxylate groups of EDTA and its complexes with Mg2+, Ca2+, Zn2+ and Al3+ have been measured at different fields and the chemical shift anisotropy determined. NMR data have also been reported for [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII], (29Si) and [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII], (29Si).

2.2 Complexes of Group 3, the Lanthanides and Actinides. – NMR data have been reported for (5), (7Li), [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII].

2.3 Complexes of Group 4. – Heterometallic triethanolamine isopropoxide derivatives of aluminium and titanium have been characterized using Al NMR spectroscopy. The NMR signals of [(η5 -neomenthylcyclopentadienyl)2TiCl2] have been assigned by use of NOE measurements. NMR data have also been reported for [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII].

2.4 Complexes of Group 5. – A review entitled 'Sandwich and half-sandwich complexes derived from [(η5-C5Me5)V(CO)4]' has appeared.

The 51V NMR spectrum of [VO{(S)-OCHMeEt}{(R)-salicylaldehyde (benzyl-mercaptothiocarbonylhydrazonate)}] shows two signals for the diastereomers. Medium effects on 51V NMR chemical shifts have been calculated for ions such as [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII], (51V). [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] has four 51V NMR signals. NMR data have also been reported for [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII], (51V), [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII], (11B), (8), (7Li), [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII], (51V), [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII], (51V), [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII], (29Si), [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII], (51Si), [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII], (119Sn), [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII], (M1 = Nb, Ta; M2 = Mn, Re; 17O), [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII], (51V), [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII], (51V), [VO(O2) (uracil-H)2]-, (51V), [VO(O2)2(bipy)] -, (51V), [VO(acetylacetamido)2], (51V), [VO(acetylacetosalicylhydrazone)(OEt)], (51V), [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII], (17O, 51V), [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] (17O, 51V, 77Se), [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII], (51V), [(acac)VOF2]-, [(acac) MoO2F2]-, (51V, 95Mo) and [NbOH(O2)2(8-quinolinolate)]-, (93Nb).

2.5 Complexes of Group 6. – A review entitled 'Synthesis and property of phosphenium complexes containing double bond character between a transition metal and a phosphorus atom', which contains 31P and 95Mo NMR data, has appeared.

Variable temperature 95Mo NMR spectra of [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII], L = substituted biphenylphenanthroline, 1,4-R2-diazabutadiene and bipyridine, show that the complexes are stable. α-Agostic interactions in [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] and related compounds have been investigated by 1H and 13C NMR spectroscopy. 13C NMR studies show that the 3-hexyne is donating four electrons to molybdenum in [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII]. 1H NMR data for [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] suggest O–H··O hydrogen bonding between the alcohol OH and the triflate O. For [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] there is a linear correlation between δ(183W) and 1J(183W31P) which allows monitoring trends in W–P multiple bonding. The 31P chemical shift of [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] is 868 ppm. NMR data have also been reported for [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] and [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII].

The 31P NMR spectrum of [(η5- C5H4Me)3Mo3S4Pt(PPh3)] shows 1J(195Pt31P) = 6656 Hz. NMR data have also been reported for [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII].

2.6 Complexes of Group 7. – 1H T1 Measurements have been used to characterize the hydrides in [ReH7(Ph2POCH2CH2OPPh2)] and [Re2H8(Ph2POCH2CH2OPPh2)]. Solution 1H NMR, NOE and T1 measurements of [K(1,10-diaza-18-crown-6][ReH6(PPh3)2] indicate NH ... HRe interactions are present in solution. The H-H distance in [ReCl2(H2) (AsMe2Ph2)4] has been estimated from 1H T1 measurements. The enantiomeric purity of [(η6-arene)Mn(CO)3]+ has been determined by 1H NMRspectroscopy using the TRISPHAT chiral anion. A detailed analysis of the COSY and TOCSY experiments has been applied to [Mn12O12(O2CEt)16(H2O)3]·4H2O. The solution structures of [MO2F3], M = Tc, Re, have been studied by 19F and 99Tc NMR spectroscopy. NMR data have also been reported for [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII]

2.7 Complexes of Group 8. – A review entitled 'NMR, IR, Mossbauer and quantum chemical investigations of metalloporphyrins and metalloproteins', which contains 13C and 17O NMR data of coordinated CO, has appeared. 1H NOE, T1 and 1J(HD) have been used to determine the structure of (10). The hydride 1H T1 value for [RuH3(SiMe2Cl2)(PPh3)3] is 340 ms indicating a classic hydride. However, the hydride shows J(29Si1H) = 39.7 Hz indicating an agostic interaction. A set of empirically derived 13C NMR chemical shift additivity constants has been calculated for the [(η5-C5H5)(OC)2Fe]-substituted cyclohexanes, dioxanes and tetrahydropyrans. Extensive use has been made of two-dimensional NMR spectroscopy, 31P1H correlation and NOESY to determine the structure of (11). The structure of the ion pairs between trans-[Ru(COMe)(pz2CH2)(CO)(PMe3)2] and anions such as [BPh4]- and [PF6]- has been investigated using 1H NOESY and 19F{1H} HOESY NMR spectroscopy. The enantiomeric purity of (12) has been determined using TRISPHAT as a chiral counter-ion. The 15N spectrum of (13) shows 2J(31P15N) = 32 Hz indicating a trans-geometry. The 31P chemical shifts of [(η5-C5Me5)Ru{=C=CHCH(OH)Ph}(Pri2PCH2CH2PPri2)] are very temperature dependent with the signal changing from AB to A2 to AB as the temperature is increased. NMR data have also been reported for [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII].