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: 'Solution and Gas Phase NMR Spectroscopy' and 'Solid-State NMR Spectroscopy'.

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: 'Connectivities in molecules by INADEQUATE: recent developments', which contains 29Si and 183W NMR spectra, 'Temperature measurements using nuclear magnetic resonance', which describes various thermometers based on 1H, 13C, 15N, 119Sn and 207Pb, 'Multiquantum filters and order in tissue', which contains 23Na NMR spectroscopy, 'Applications of advanced experimental techniques: high pressure NMR and computer simulations', '2H NMR relaxation as a method for characterisation and study of transition metal hydride systems in solution', 'NMR relaxation studies of polynuclear hydrides derivatives', 'A Half-century of nonclassical organometallic chemistry: A personal perspective', 'NMR studies of metal complexes and clusters with carbonyls and phosphines', 'Adventures in organometallic NMR: steric restraints, slowed rotations, and skeletal rearrangements', 'Applications of pulsed-gradient spin-echo (PGSE) diffusion measurements in organometallic chemistry'," 'Metal ion-assisted interactions involving biological molecules. From small complexes to metalloproteins', '113Cd and 207Pb NMR spectroscopic studies of calcium-binding proteins', 'Local and band susceptibility on π-d hybridised organic-inorganic system disclosed by site-selective NMR', and 'Relaxation and dynamics of molecules in the liquid crystalline phases'.

A number of papers have been published which are too broadly based to fit into a later section and are included here. NMR chemical shifts have been calculated for H2, N2, NH3, CH4, C2H4, HCN, MeCN and H2O. The magnetic shielding has been calculated for [CO3]2-, [NO3]-, [SO4]2- and [N]3-. Calculated and experimental 15N shifts of NaN5, KN5, Mg(N5)2, Ca(N5)2 and Zn(N5)2 have been reported. 31P and 35Cl PGSE diffusion studies have been applied to phosphine ligands and selected organometallic complexes. The direct determination of 119Sn, 195Pt, 199Hg and 204Pb NMR correlation times from spin-lattice and spin-spin relaxation times has been described. 3He, 11B, 21Ne, 27Al and 69Ga NMR chemical shifts have been calculated for icosahedral closo-borane, -alane and -gallane dianions with endohedral noble gas atoms and their lithium salts. The nuclear magnetic shielding polarisabilities of N2, F2, CO, HF, HCl, HCN, HNC and C2H2 have been computed. The 19F NMR chemical shieldings of M1F2, M1 = Zn, Cd, Pb, M2F2, M2 = Al, Ga, In, and SnF4, have been studied by the GIAO-B3LYP method.

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. – 87Rb-129Xe spin exchange and relaxation rates have been measured at high pressure and high magnetic field. 1J(1H-1H) and 3J(M-X) coupling constants have been examined as fingerprints for hydrogen bond type. The 7Li NMR spectra of [Li2C4Ph2(SiMe3)2] indicate that the two lithium atoms are considerably shielded by the ring current. NMR data have also been reported for [LiBun], (6Li), [LiCH2-2-(1-Me-imidazole)], (6Li), [Li(THF)4][Li{C(SiR3)Ph2}2], (7Li, 29Si), [CuLi2CN)], (6Li), [({(S)-α-(PhCHMe)(CH2CH = CHLi)N})Li]6, (7Li), [LiButLiC6H3-2,6(C6H2-2,4,6- Pri3)2], (7Li), [MLi2XAr2], (M = Cu, Ag, Au; 6Li), (1), (7Li), [Li{Si({NCH2But} 2C6H4-1,2)R}L], (7Li, 29Si), [(But2MeSi)3MLi], (M = Si, Ge; 29Si), [Na{C(SiMe3)Ph2}]n (23Na, 29Si), and [Cs(PC4Me4)], (133Cs).

6LiH HOESY experiments have shown that in (2), lithium prefers the five-membered chelate while sodium prefers the six-membered chelate. 15N T1 measurements have been used to study Li+ binding to the nitrogens in polyphosphazenes. 7Li1H HOESY has been applied to probe solvent-cellulose interactions in cellulose dissolution. The relaxation characteristics in the 17O NMR spectra of Na+ and K+ water clusters have been reported. 23Na and 31P NMR spectra have been used to study the time course of myocardial sodium accumulation after burn trauma. The phase behaviour of a mixture of phospholipid bicelles has been investigated using 2H, 23Na and 31P NMR spectroscopy. 1H and 13C NMR chemical shifts have been calculated for Ag+, K+ and Rb+ salts of hydroorotate (2,6-dioxo-1,2,3,6-tetrahydropyrimidine-4-carboxylate) anion. 87Rb MRI has been used to follow Rb+ uptake in pig hearts. NMR data have also been reported for [Li4B(N-2-pyridyl)3(NH-2-pyridyl)(THF)3], (7Li, 11B), [LiMg(NPri2)2(OR)]2, (7Li), [ArfC(NSiMe3)2Li]n, (29Si) [PhCH2NLiN-(SiMe3)CH2Ph], (7Li, 29Si), [Li{μ-N(SiMe3)2}2 Ca{N(SiMe3}2], (7Li), [Li{Si[(NCH2But)2C6H4-1,2]R}(THF)2], (7Li, 29Si), [(C6H4-1-OMe-2- NSiMe3)Li(OEt2)]2, (7Li), [(But2SiFLiNBut)2OEt2)], (29Si), [1,8-{(Me3SiN)Li(THF)}2C10H6], (7Li, 29Si), [{Me2Si(2,6- Pri2C6H3)NLi}2]2, (7Li, 29Si), [2-PhC6H4NLi2]n [2-PhC6H4N{B(NMe2)2}2], [2- PhC6H4N(SiMe3)2], (7Li, 11B, 29Si), [Li{N(C6H3Me2- 2,6)CC(SiMe3)Si(SiMe3)2N(C6H3Me2-2,6)}(tmeda)], (7Li), [Li2{C6H4-1,3-(CH2NC6H3-2,6- Pri2)2}], (7Li), [Yb{(N{SiMe3}CPh)2CH-μ-Li(THF)}2], (7Li, 29Si), [Li{Me2(MeO)SiNC(Ad)-CHSiMe3}2], (7Li, 29Si), [Li2(THF){P(O)(NBut)2(NHBut)}]2, (7Li),62 (3), (7Li, 29Si), [CyPSe3Li2(tmeda)2], (77Se), [(THF)2Li2{PhP(Se)(NBut)2}2], (7Li, 77Se), [Li(tmeda)2][Te(NBut)P(μ- NBut)2P(NBut)Te], (7Li, 125Te), [{As(NBut)3}2Li6], (7Li), [{Sb(μ-NCy)2(μ- N)}3{Li(THF)}3], (7Li, 14N), [M{N(SiMe3) = CC6H3-2,6-Me2}2SiSiMe3], (29Si), Li+ in polyacrylonitrile-based electrolytes, (7Li), Li containing lipophilic nucleosides, (7Li), [{(2-O-4-Me- quinoline)Li}8 (THF)4], (7Li), Li-crown ether complexes, (7Li), [M3L3], {M = Li, Na; L = (4); 7Li, 23Na}, [Li6K6M(Pri3SiP)6(OSiMe3)2], (M = Sr, Ba; 7Li, 29Si), [(But3SiO)4Na4],(29Si),76 and Cs+ in phosphonato cavitands, (133Cs).

2.2 Complexes of Group 2. – Two relevant reviews have appeared: '23Ca NMR of calcium-binding proteins' and 'Shape and dynamics of calcium-binding protein investigation by 15N NMR relaxation'.

The quadrupole moments of 41Ca and 41Sc have been determined. Evidence of a near-critical solvation effect on rotational correlation time of 9Be NMR T1 of [Be(acac)2] has been obtained in liquid and supercritical CO2. The 1H and 13C NMR signals of bacteriochlorophyll a have been assigned. NMR chemical shifts of [ML2], M = Mg, Ca, Sr, Ba, L = [2,6-Pri2C6H3NCMeCHCMeNC6H3-2,6- Pri2] point to increased ionicity of the ligand-metal bond in the order Mg

2.3 Complexes of Group 3, the Lanthanides, and Actinides. – The quadrupole moment of 41Sc, and the magnetic moment of 48Sc, have been determined. Three isomers of [Tm/C82] have been studied by 13C NMR spectroscopy. 1J (89Y31P) = 144 Hz and 1J (31P1H) = 201 Hz in [(THF){1,3-(Me3 Si)2C5H}2Y{PH(SiButS)}] U NMR chemical shifts have been calculated for some diamagnetic uranium compounds. NMR data have also been reported for [{HB(3,5-But, Me-C3HN2)3}Yb(μ-D)]2, (2H, 171Yb), [Li(THF)4] [Yb{CH (SiMe3)2}3], (7Li, 29Si, 171Yb), [Y(η5:η 1-C5Me4CH2SiMe2 NBut)(μ-2-C4H3O)]2, (89Y), [(η5-C5H5) 2Y{N(SiMe3)2PPh2}2 CH2], (29Si), [(η6-3,5-Me2 C5H3BNMe2)2Y(μ-Cl) 2Li]2, (7Li, 11B), [({(Et2CH2CH2NCMe)2CH} Mg-Br)2ScBr], (45Sc), [Sc(acac)2 (μ-Cy7Si8O12)]2, (29Si), [ScXx(OPMe3)6-x], 3-x (45Sc), [Y{μ-OPri)2 M(OPri)}3], (M = Nb, Ta; 89Y), and [Yb(NPh)2(THF)4], (171Yb).

2.4 Complexes of Group 4. – The 1H and 13C chemical shifts of [(η5-C5H5) Zr(μ-Me)AlMe3][Me2AlO] and [(η 5-C5H5)2ZrMe][Me2 AlO] have been calculated and compared with experiment. The size of the ion pair, [(η5-C5H5)2 Zr(μ-Me)AlMe3][Me2AlO], has been determined by PFG NMR spectroscopy. 1H-1H TOCSY and 1 H-1H NOESY have been used to study the structures of a series of substituted indenyl titanium and zirconium complexes. The reactivity of some substituted cyclopentadienyl zirconium chloride/[Me AlO]n towards H2 has been correlated with 91Zr chemical shifts.10H-H NOESY has been used to identify [{η 5-1-(2-MeOC6H4)-indenyl}2 ZrCl2]. There is a correlation of 13C NMR and IR data for a zirconacyclopropene. The coordinative interaction of various organoaluminiums with [ZrCl4] has been studied using 1H and 27Al NMR spectroscopy. NMR data have also been reported for [(η5-C5H5) Zr(μ-H)2BC5H10], (11B), [Ti(CH2SiMe3)(NMe2){MeN (CH2-2-pyrrole)}], (14N), [MeSi{SiMe2 N(C6H4-4-Me)}3SnZr(η5-C 5H5)2Me], (29Si, 119Sn), [Zr3Al(μ4-O)(μ-OMe)6Cl6 Me(THF)3], (27Al), [(η5-C5 Me5)Hf(η4-C6H10)(CH2 SiMe3)], (29Si), (5), (29Si), [{(Me3Si)2N}(C2H4Si2 Me4N)-Ti(C[equivalent to]CR)2], (11B, 15N, 29Si), [(2,6-Pri2C6 H3)N = Hf(THF)2(SiPh3)2], (29Si), [η5-C5H3C5 H8)2Ti(η2-Me3SiC[equivalent to] CSiMe3)], (29Si), (6), (15N), [(η5-C5H5){η5-(Et 3SiCH2CH2)3SiC5 H4}TiCl2], (29Si), (7), (15N), (8), (29Si), [(η5-C5 H5)-(OC)2FeCH2SiMe2OZrCl (η5-C5H5)2], (29Si), [(η5-C5H5)2Zr(μ-O2 BC6H2-2,4,6-Me3)], (11B), [(η5-C5Me5)(η6-C5 H5BCH = CHPh)ZrCl2], (11B), (9), (11B), [Tl4,Ti2(μ-O)(μ3-OEt) 8(OEt)2], (205Tl), [{9-(Me3Si) fluorenyl}4O12(TiOBut)4], (29Si), [(H2C = CH)Cy6Si7O 12TiOPri], (29Si), [(Zr6NCl 12)Cl6]3-, (15N), and [(Me 2NCH2CH2NMe2)HfCl2 {Si(SiMe3)3}], (29Si).

2.5 Complexes of Group 5. – The 31P and 51V NMR spectra of [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] show 51V coupling. NMR data have also been reported for [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] (11B, 29Si), [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] (29Si), (10), (11C), (11), (11B), (12), (7Li), [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] (29Si), [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] (15N), (7Li, 29Si).

The 14N NMR signals of the terminal and bridging imido groups of some imidovanadium complexes show marked differences in their lineshapes that could be used as an additional criterion for signal assignment. NMR data have also been reported for [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] (13), (51V), 1: complexes between aryl hydroxamic acids and vanadate, (15N, 51V), [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] (51V), vanadyl complexes of [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] (51V) [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] (L = tridentate aryloxy ligand, 15N), and (14), (29Si).