Trends in NMR chemical shifts of d0 transition metal compounds

Chen, Xue-Tai; Cook, Tabitha M.; Lamb, Adam C.

doi:10.1016/j.jorganchem.2017.03.044

Cited by 14 publications

(17 citation statements)

References 227 publications

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“…The corresponding signal for the carbon atom is extremely shifted to lower fields at δ =277.2 ppm, which can be observed in the DEPT135 NMR spectrum. This value is comparable to other d 0 early transition‐metal carbene complexes . Owing to the coupling of the carbon atom to the 93 Nb quadrupolar nucleus ( I =9/2, 100 %), the carbene signal is not observed in the standard 13 C NMR experiment.…”

Section: Methodssupporting

confidence: 78%

Bis(η⁵:η¹‐pentafulvene)niobium(V) Complexes: Efficient Synthons for Niobium Carbene and Imido Derivatives

et al. 2018

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Transition-metal carbene complexes and their reactivities are akey topic of chemistry.They are an integral part of researches in catalysis,organic synthesis,coordination chemistry,a nd numerous other areas.I nt his context, we report the synthesis of al ow-valent bis(h 5 :h 1 -(di-p-tolyl)-pentafulvene)niobium chloride.O wing to the p-h 5 :s-h 1 coordination mode of the pentafulvenes and the resulting high nucleophilic character of the exocyclic carbon atom of the ligand, the bis(h 5 :h 1 -pentafulvene)niobium complex is able to achieve the umpolung of ac oordinated vinyl unit and the resulting formation of the first h 5 :h 1 cyclic niobium Schrock carbene complex. This new synthetic route is,incomparison to classical a-hydrogen elimination reactions or thermolysis of diazo compounds,c ompletely unprecedented. The reactivity of the cyclic carbene function and the remaining fulvene ligand is demonstrated by double NÀHb ond activation of primary amines to niobium imido complexes.

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Section: Methodssupporting

confidence: 78%

Bis(η⁵:η¹‐pentafulvene)niobium(V) Complexes: Efficient Synthons for Niobium Carbene and Imido Derivatives

et al. 2018

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“…This value is comparable to other d 0 early transition-metal carbene complexes. [26] Owing to the coupling of the carbon atom to the 93 Nb quadrupolar nucleus (I = 9/2, 100 %), the carbene signal is not observed in the standard 13 CNMR experiment. The protons of the acyclic CH 2 group along the Nb = CH unit generate an ABX-system with coupling constants of 2 J AB = 18.1 Hz, 3 J AX = 6.7 Hz, 3 J BX = 4.8 Hz.…”

Section: Methodsmentioning

confidence: 99%

Bis(η⁵:η¹‐pentafulvene)niobium(V) Complexes: Efficient Synthons for Niobium Carbene and Imido Derivatives

et al. 2018

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Transition-metal carbene complexes and their reactivities are a key topic of chemistry. They are an integral part of researches in catalysis, organic synthesis, coordination chemistry, and numerous other areas. In this context, we report the synthesis of a low-valent bis(η :η -(di-p-tolyl)-pentafulvene)niobium chloride. Owing to the π-η :σ-η coordination mode of the pentafulvenes and the resulting high nucleophilic character of the exocyclic carbon atom of the ligand, the bis(η :η -pentafulvene)niobium complex is able to achieve the umpolung of a coordinated vinyl unit and the resulting formation of the first η :η cyclic niobium Schrock carbene complex. This new synthetic route is, in comparison to classical α-hydrogen elimination reactions or thermolysis of diazo compounds, completely unprecedented. The reactivity of the cyclic carbene function and the remaining fulvene ligand is demonstrated by double N-H bond activation of primary amines to niobium imido complexes.

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“…Note that throughout section we will use the notation LA for light atoms and also for heavier spectator NMR atoms (e.g., Se or Te) in the vicinity of an even heavier HA. Based on refs , , , , , , , , , , and − , the following general rules can be derived for periodic trends in the SO-HALA shifts: A formally empty valence shell at the HA (p 0 , d 0 , or f 0 configuration) gives rise to SO-HALA deshielding of LA(s) bonded directly. This is the case particularly for HAs with 5d 0 and a positive oxidation state Cs I –Os VIII , for 6p 0 Hg II –Bi III (the 6s 2 shell is present but unimportant in this context), and for 6d 0 5f 0 Ac III –U VI . ,,,, For the corresponding lighter analogs, the effect exists in diminished form (Figure ).…”

Section: Trends In So-hala Shifts Across the Periodic Tablementioning

confidence: 99%

Relativistic Heavy-Neighbor-Atom Effects on NMR Shifts: Concepts and Trends Across the Periodic Table

et al. 2020

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Chemical shifts present crucial information about an NMR spectrum. They show the influence of the chemical environment on the nuclei being probed. Relativistic effects caused by the presence of an atom of a heavy element in a compound can appreciably, even drastically, alter the NMR shifts of the nearby nuclei. A fundamental understanding of such relativistic effects on NMR shifts is important in many branches of chemical and physical science. This review provides a comprehensive overview of the tools, concepts, and periodic trends pertaining to the shielding effects by a neighboring heavy atom in diamagnetic systems, with particular emphasis on the "spin-orbit heavy-atom effect on the light-atom" NMR shift (SO-HALA effect). The analyses and tools described in this review provide guidelines to help NMR spectroscopists and computational chemists estimate the ranges of the NMR shifts for an unknown compound, identify intermediates in catalytic and other processes, analyze conformational aspects and intermolecular interactions, and predict trends in series of compounds throughout the Periodic Table . The present review provides a current snapshot of this important subfield of NMR spectroscopy and a basis and framework for including future findings in the field.

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Trends in NMR chemical shifts of d0 transition metal compounds

Cited by 14 publications

References 227 publications

Bis(η⁵:η¹‐pentafulvene)niobium(V) Complexes: Efficient Synthons for Niobium Carbene and Imido Derivatives

Bis(η⁵:η¹‐pentafulvene)niobium(V) Complexes: Efficient Synthons for Niobium Carbene and Imido Derivatives

Bis(η⁵:η¹‐pentafulvene)niobium(V) Complexes: Efficient Synthons for Niobium Carbene and Imido Derivatives

Relativistic Heavy-Neighbor-Atom Effects on NMR Shifts: Concepts and Trends Across the Periodic Table

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Trends in NMR chemical shifts of d0 transition metal compounds

Cited by 14 publications

References 227 publications

Bis(η5:η1‐pentafulvene)niobium(V) Complexes: Efficient Synthons for Niobium Carbene and Imido Derivatives

Bis(η5:η1‐pentafulvene)niobium(V) Complexes: Efficient Synthons for Niobium Carbene and Imido Derivatives

Bis(η5:η1‐pentafulvene)niobium(V) Complexes: Efficient Synthons for Niobium Carbene and Imido Derivatives

Relativistic Heavy-Neighbor-Atom Effects on NMR Shifts: Concepts and Trends Across the Periodic Table

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Bis(η⁵:η¹‐pentafulvene)niobium(V) Complexes: Efficient Synthons for Niobium Carbene and Imido Derivatives

Bis(η⁵:η¹‐pentafulvene)niobium(V) Complexes: Efficient Synthons for Niobium Carbene and Imido Derivatives

Bis(η⁵:η¹‐pentafulvene)niobium(V) Complexes: Efficient Synthons for Niobium Carbene and Imido Derivatives