Publisher Summary Inorganic lead compounds as stabilizers for polymers or as components in glasses, the toxicity of lead chemicals, and basic research in organolead chemistry are important topics of discussion. In lead chemistry, nuclear magnetic resonance (NMR) spectroscopy has become one of the prominent tools for studying lead compounds in solution, and it may also be valuable for studying various classes of solid lead compounds. This chapter aims to present the results of the study of 207 Pb NMR measurements performed in liquids. In addition, the chapter outlines some aspects of the solid-state 207 Pb NMR, as it is a rapidly growing area at present. Multinuclear magnetic resonance (mNMR) is used for obtaining consistent information on the systems under consideration. A larger set of 207 Pb NMR data helps in understanding the NMR parameters of the lighter magnetically active isotopes in Group IV of the periodic table, in particular for l19 Sn and 29 Si nuclei. Furthermore, 207 Pb NMR parameters serve as a crucial test for the validity of theoretical models, aiming at the description of chemical and physical properties of the heavy elements. Many old problems in the solid-state chemistry of lead can be tackled, taking advantage of the improvements in modern NMR instrumentation.

207Pb-NMR Parameters

Metal NMR of organometallic (d-block) systems

Zum reaktionsverhalten eines vinylidentitanocen-intermediates gegenüber protischen agenzien—selektive synthesen von 1-alkenyltitanocenverbindungen

207 Pb NMR parameters [chemical shifts δ 207 Pb, indirect nuclear spin—spin coupling constants n J ( 207 Pb,X), and relaxation times T 1 ( 207 Pb), T 2 ( 207 Pb)] are listed and discussed with respect to the structure and dynamics of lead compounds, focusing mainly on the liquid state. Referencing of δ 207 Pb data is described, as well as the usual experimental techniques for observing 207 Pb NMR signals. The importance of the chemical shift anisotropy (CSA) as a relaxation mechanism at moderate to high field strengths is emphasized. Patterns of δ 207 Pb data (range of ≈ 17000 ppm with plumbylenes at the high frequency and plumbocenes at the low frequency end) are related to structure, substituent effects, and the lead coordination number. Contributions of relativistic effects to 207 Pb nuclear shielding become obvious, in particular for lead(II) compounds. Isotope-induced chemical shifts n ΔX ( 207 Pb) may attract more attention in the future. Many coupling constants n J ( 207 Pb,X) are reported, where X stands for numerous nuclei throughout the Periodic Table. The determination of the sign of n J is demonstrated for various examples. It is shown that these signs are not always predictable, even for X = 13 C and n = l, and therefore experimental evidence is required.

Application of 207Pb NMR parameters

Synthesis, Crystal Structures, and Fluxional Behavior of Donor-Bridged Bis(silylene)molybdenum and -chromium Complexes

Nuclear magnetic resonance measurements of metallic nuclei (δ 207Pb, δ 95Mo, and 1J(W–Pb)) have been carried out on dimetallic Cp(CO)3MPbR3 (M = Mo, W; R = Me, Et, Ph) and trimetallic [Cp(CO)3M]2PbPh2 (M = Mo, W) complexes. 207Pb chemical shifts increase in the sequence PbEt3 < PbMe3 < PbPh3 and are observed at higher fields in the tungsten compounds than in the molybdenum ones. It is suggested that both paramagnetic and diamagnetic contributions determine the overall shielding of lead, and that the higher field resonances of 207Pb in the case of W–Pb compounds are due to an efficacious operation of the Z/r dependent diamagnetic term (higher atomic number Z of tungsten and roughly the same Mo–Pb and W–Pb distances resulting from the 4f level induced lanthanide contraction). 95Mo chemical shifts (−1838 to −2007 ppm) lie in the region typical of the molybdenum – main group metal bonded complexes but at lower fields than in the corresponding Mo–Sn compounds. It is concluded from this observation that the Z/r...

Cyclopentadienyl complexes with transition metal – main group metal bonds. VII. 207Pb and 95Mo nuclear magnetic resonance studies on molybdenum and tungsten complexes [(η5-C5H5)(CO)3M]nPbR4−n (n = 1, R = Me, Et, Ph; n = 2, R = Ph)

Transition metalcyanocarbon chemistry. Part V. Crystal and molecular structure of biscyclopentadienyl complexes containing a σ-cyanoalkyl and a σ-cyanoalkenyl ligand: (η5-C5H5)2Mo[S(C6H5)](σ-CH(CN)CH3) and (η5-C5H5)2Mo(S2CN(C2H5)2)(σ-C(CN)CH2)

Transition metalcyanocarbon chemistry. Part IV. Reactions of bent biscyclopentadienyl complexes of molybdenum and tungsten of the type (η5-C5H5)2MH(σ-CRCHR′) (M = Mo, W; R = CN; R′ = H; M = Mo; R = CN, CF3; R′ = H; R = R′ = CN) and (η5-C5H5)2Mo(σ-C(CN)CH2) ((Z)-CHCHCN) with HX (X = Cl, O2CCF3, SPh, SMe, SH) reagents. Protonation of σ-alkenyl ligands

Luiz C. Gomes De Lima

Papers

Cyclopentadienyl complexes with transition metal – main group metal bonds. VII. 207Pb and 95Mo nuclear magnetic resonance studies on molybdenum and tungsten complexes [(η5-C5H5)(CO)3M]nPbR4−n (n = 1, R = Me, Et, Ph; n = 2, R = Ph)

Transition metalcyanocarbon chemistry. Part V. Crystal and molecular structure of biscyclopentadienyl complexes containing a σ-cyanoalkyl and a σ-cyanoalkenyl ligand: (η5-C5H5)2Mo[S(C6H5)](σ-CH(CN)CH3) and (η5-C5H5)2Mo(S2CN(C2H5)2)(σ-C(CN)CH2)