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, 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.

One book has been published which is relevant to this review:- 'Studies in Inorganic Chemistry, 13: Transition Metal Nuclear Magnetic Resonance', ed. by P.S. Pregosin.

Several relevant reviews have been published, including 'Molecular hydrogen (η2-H2) complexes of transition metals, 'Metal NMR chemical shifts of polynuclear early transition metal complexes with direct metal-metal bonds' 'Electronic states of transition metal complexes and the electronic mechanism of metal-nucleus NMR chemical shifts' 'Synthesis and characterization of heterometallic carbonyl cluster anions', 'Applications of spectroscopic measurements to homogeneous catalysis', and 'Use of NMR spectroscopy in the study of glass structure. I. NMR spectroscopy of silicate solutions'.

A number of papers have been published which are too broadly based to fit into a later section and are included here. The use of 1J(13 C1H) as a criterion of agostic bonding has been examined for C2H4 coordinated to early transition metals. N NMR spectroscopy has been used to probe the bonding, bending and fluxionality of the imido ligand on Ta, Mo, W, Re, and Os. Inorganic phosphates have been analysed quantitatively using 31P NMR spectroscopy.' The solution and solid state conformations of Ni2+, Zn2+, Cd2+, and Hg2+ have been investigated both in solution and the solid state by 13C NMR spectroscopy and in solution by 199Hg NMR spectroscopy. The relaxation and dynamical properties of water in partially filled porous materials have been investigated using NMR techniques. The measurement of I = 5/2 relaxation in biological and macromolecular systems using multiple-quantum NMR techniques has been described and applied to 17O, 25Mg, and 27Al. The characterisation of compounds using 13C and 29Si NMR spectroscopy has been discussed, NMR data have also been reported for 1-Me3Si-cycloocta-1,5-diene complexes with RhI, PdII, PtII, and AgI, (13C), pyridoxalisonicotinoyl hydrazone complexes with some 3 d metal ions, (13C), 17U, Mo, W, Re, Rh, and Pd complexes of (1), (13C), NiII and ZnII complexes of (2), (13C), salicylaldehyde-2-aminobenzophenone-2-thenoylhydrazone complexes with 3d metal ions, (13C), [M(RNCMeCH2CMe2NHR)]2+, (M = Co, Ni, Zn, Cd; 13C), complexes of metals with 1,15-diaza-3,4:12,13-dibenzo-5,8, 11-trioxacyclooctadecane, (13C), and metal complexes of 4-acyl-5-pyrazolone, (13C).

2 Stereochemistry

This section is subdivided into eleven parts which contain n.m.r. 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.

Complexes of Groups 1 and 2. — Reviews entitled 'NMR of lithium-6 enriched organolithium compounds', and 'Applications of NMR in sensory science', which includes Na NMR spectroscopy, have appeared.

The 13C NMR spectrum, including IJ(13 C6Li), has been reported for [LiCH2NMeCH2 CH2-NMeCH2CH2NMe2]. 6Li-6Li COSY of PriLi/sparteine in Et2O shows coupling between two sites. The 13C NMR spectrum was also reported. The structures of [Ph3CLi] and [Cs(3-Et-3-heptoxide)] in solution have been studied using 6Li, 1H HOESY, 133Cs, 1H HOESY, and 1H, 1H ROESY, and close contacts identified. 6Li,1H HOESY has been used to determine Li — H distances to an accuracy of ca 0.2 Å in [C2H3Li.thf]4. The solution structures of [[Li(TMEDA))2(Me3Si-CH=CH)2] and [(Li(TMEDA))2(Me3SiCH=CMe)2] have been determined using 7Li, 1H HOESY. 7Li T1 measurements were also reported. The one-dimensional and two-dimensional 6Li, 6Li INADEQUATE experiments have been described and applied to compounds such as (E)-1-Li-2- (2-LiC6H4)-1-Ph-hex-1-ene. [2-Me2N-6-Bu1 O-C6H3Li] shows extreme distortion of the benzene ring from hexagonal at Li and a very low 1J(13C13C) of 27.8 Hz results. The 6Li NMR spectrum was also recorded. 13C NMR spectroscopy, 6Li,1H HOESY, and HETCOR have been used to determine the structure of (3). 6Li, 13C, and 15N NMR spectroscopic studies have been used to show that [LiNPri2] in neat TMEDA is a dimer. Heteronuclear multiple quantum correlation has been used to correlate 6Li and 15N chemical shifts of mixed aggregates of [6Li, 15N] lithium 2,2,6,6-tetramethylpiperidide with 6LiBr, 6LiCl, and 6Li(OC6H11). The aggregated forms of [LiNPri2] and Li 2,2,6, 6-tetramethylpiperidide in THF have been unambiguously shown to be dimers rather than trimers or higher oligomers by 6Li detection of 15N homonuclear zero quantum coherence. 6Li, 1H HOESY and 13C NMR spectroscopy have been applied to (4). 13C NMR spectroscopy has been used to study the structure of the complex of CH2(CH2O-I-C6H4-2-OCH2) 2CHCH2OP(O)(OH)-(OBun) with Li+. A method has been developed to measure Li+ concentrations in the human brain using in vivo1H and 7Li NMR spectroscopy. NMR data have also been reported for [LiCH(CN)2(H2O)(TMEDA)], (1Li, 1H HOESY, 13C), [(PhC=CLi)4 (TMEDA)2], (13C),' (5),( 13C), (6), [C6H4CH=CHSnBun2], (6Li, 13C, 119Sn), [Li(C6H2Ph3). 2Et2O], (13C),[(Li(2,4,6-But3 C6H2))(LiP(H)(2,4,6-But3C6 H2))]2, (7Li),45 [(Et2N)Ph2 SiLi], (13C), [(2,4,6-Me3C6H2)H2 GeLi], (13C), [((Et2O)Li)2(Ph(Me2N)BB (NMe2)Ph)], (11B), [Li(l2-crown-6)][(THF)Li (µ-NSiMeBut2)2SiBut], (7Li, 13C, 29Si), (7), (6Li, 15N) [Li(PhNPPh2)(OEt2)]2, (7Li), [((BUtNPNC6H2BUt3,2,4, 6) Li)n(Et2O)m], (7Li), (8), (7Li, 13C, 29Si), [(Me3SiN)2-SPhLi]2 OEt2, (6Li, including 6Li, 1H HOESY, 7Li, 13C, 29Si), (9), (7Li, 11B, 13C), and LiHC(O)PH.DME, (13C).

23Na NMR spectroscopy has been used to study the binding of Na+ to N(CH2CH2N=CHXCH=N-CH2CH2)3N, X = 2,5-furyl, 2,6-pyridyl, 2,5-pyrole, or 2,6-4-Me-phenol. The conformation of the potassium salt...