Bright luminescent lithium and magnesium carbene complexes

Pinter, Piermaria; Schüßlbauer, Christoph M.; Watt, Fabian A.; Dickmann, Nicole; Herbst‐Irmer, Regine; Morgenstern, Bernd; Grünwald, Annette; Ullrich, Tobias; Zimmer, Michael; Hohloch, Stephan; Guldi, Dirk M.; Munz, Dominik

doi:10.1039/d1sc00846c

Cited by 28 publications

(38 citation statements)

References 149 publications

(139 reference statements)

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“…The lithium and magnesium complexes 137 and 138 ( Scheme 29 ) containing CNC pincer ligand featuring carbazole-based bis-MIC donors show bright luminescence. 61 Their photophysical properties have been investigated by absorption and luminescence spectroscopy. The lithium and magnesium centers prevent the distortion of the ligand following excitation, which supports bright luminescence by avoiding nonradiative deactivation.…”

Section: Redox Photochemical/photophysical Properties Of Metal Complexesmentioning

confidence: 99%

“…The lithium and magnesium centers prevent the distortion of the ligand following excitation, which supports bright luminescence by avoiding nonradiative deactivation. 61 A MIC-containing macrocyclic scandium complex exhibits fluorescence. 60 As the corresponding triazolium ligand displays similar fluorescent behavior, the excited and emissive states are likely ligand-centered.…”

Section: Redox Photochemical/photophysical Properties Of Metal Complexesmentioning

confidence: 99%

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Chemistry of Compounds Based on 1,2,3-Triazolylidene-Type Mesoionic Carbenes

Maity

Sarkar

2021

JACS Au

106

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Mesoionic carbenes (MICs) of the 1,2,3-triazolylidene type have established themselves as a popular class of compounds over the past decade. Primary reasons for this popularity are their modular synthesis and their strong donor properties. While such MICs have mostly been used in combination with transition metals, the past few years have also seen their utility together with main group elements. In this paper, we present an overview of the recent developments on this class of compounds that include, among others, (i) cationic and anionic MIC ligands, (ii) the donor/acceptor properties of these ligands with a focus on the several methods that are known for estimating such donor/acceptor properties, (iii) a detailed overview of 3d metal complexes and main group compounds with these MIC ligands, (iv) results on the redox and photophysical properties of compounds based on MIC ligands, and (v) an overview on electrocatalysis, redox-switchable catalysis, and small-molecule activation to highlight the applications of compounds based on MIC ligands in contemporary chemistry. By discussing several aspects from the synthetic, spectroscopic, and application point of view of these classes of compounds, we highlight the state of the art of compounds containing MICs and present a perspective for future research in this field.

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Section: Redox Photochemical/photophysical Properties Of Metal Complexesmentioning

confidence: 99%

Section: Redox Photochemical/photophysical Properties Of Metal Complexesmentioning

confidence: 99%

Chemistry of Compounds Based on 1,2,3-Triazolylidene-Type Mesoionic Carbenes

Maity

Sarkar

2021

JACS Au

106

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“… 5 − 7 After their initial reporting by Albrecht et al , 8 they quickly became prominent synthetic targets for (electro-)catalysis, 9 − 23 supramolecular chemistry, 24 − 27 magnetism, 28 and photochemistry due to their versatile synthesis and comparatively straightforward handling. 29 − 36 Throughout these studies, a great effort has been made to decipher their electronic structure. Mesoionic carbenes are commonly believed to be strong σ-donor ligands paralleling heteroaryls; however, recent reports emphasize their π-accepting properties 37 − 39 as demonstrated by the isolation of a reduced triazolinylidene ligand.…”

Section: Introductionmentioning

confidence: 99%

“…Almost two decades after the first report of an abnormal 5-imidazolinylidene carbene complex, mesoionic carbenes have been developed into a distinguished ligand class. , Among them, 1,2,3-triazole derived mesoionic carbenes, namely 1,2,3-triazolinylidenes, stand out by their modular synthesis via the copper-catalyzed [3 + 2] cycloaddition between azides and alkynes. − After their initial reporting by Albrecht et al , they quickly became prominent synthetic targets for (electro-)catalysis, − supramolecular chemistry, − magnetism, and photochemistry due to their versatile synthesis and comparatively straightforward handling. − Throughout these studies, a great effort has been made to decipher their electronic structure. Mesoionic carbenes are commonly believed to be strong σ-donor ligands paralleling heteroaryls; however, recent reports emphasize their π-accepting properties − as demonstrated by the isolation of a reduced triazolinylidene ligand .…”

Section: Introductionmentioning

confidence: 99%

Mesoionic Carbenes in Low- to High-Valent Vanadium Chemistry

et al. 2021

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We report the synthesis of vanadium(V) oxo complex 1 with a pincer-type dianionic mesoionic carbene (MIC) ligand L 1 and the general formula [VOCl(L 1 )]. A comparison of the structural (SC-XRD), electronic (UV–vis), and electrochemical (cyclic voltammetry) properties of 1 with the benzimidazolinylidene congener 2 (general formula [VOCl(L 2 )]) shows that the MIC is a stronger donor also for early transition metals with low d-electron population. Since electrochemical studies revealed both complexes to be reversibly reduced, the stronger donor character of MICs was not only demonstrated for the vanadium(V) but also for the vanadium(IV) oxidation state by isolating the reduced vanadium(IV) complexes [Co(Cp*) 2 ][1] and [Co(Cp*) 2 ][2] ([Co(Cp*) 2 ] = decamethylcobaltocenium). The electronic structures of the compounds were investigated by computational methods. Complex 1 was found to be a moderate precursor for salt metathesis reactions, showing selective reactivity toward phenolates or secondary amides, but not toward primary amides and phosphides, thiophenols, or aryls/alkyls donors. Deoxygenation with electron-rich phosphines failed to give the desired vanadium(III) complex. However, treatment of the deprotonated ligand precursor with vanadium(III) trichloride resulted in the clean formation of the corresponding MIC vanadium(III) complex 6 , which undergoes a clean two-electron oxidation with organic azides yielding the corresponding imido complexes. The reaction with TMS-N 3 did not afford a nitrido complex, but instead the imido complex 10 . This study reveals that, contrary to popular belief, MICs are capable of supporting early transition-metal complexes in a variety of oxidation states, thus making them promising candidates for the activation of small molecules and redox catalysis.

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“…The exploration of MIC-based pincer ligands has attracted a great deal of attention in the past decade, leading to the isolation of several interesting pincer platforms. For instance, a series of anionic CNC tridentate ligands composed of carbazole and two MIC carbenes efficiently coordinate with transition metals with the respective complexes displaying remarkable catalytic and photophysical applications . Moreover, the coordination chemistry and applications of MIC-based CNC pincer ligands featuring central pyridine rings, COC ligands with a central ether fragment, and phenolate-derived OCO pincers have also been reported recently.…”

Section: Introductionmentioning

confidence: 99%

Palladium(II) Complexes of a Neutral CCC-Tris(N-heterocyclic carbene) Pincer Ligand: Synthesis and Catalytic Applications

et al. 2021

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Treatment of tris-azolium precursor 1 with palladium acetate under thermal conditions provided a CCC-pincer palladium(II) complex (2) bearing three NHCs (one imidazolylidene and two triazolylidenes) and one iodide ligand. Further treatment of complex 2 with an excess of AgSbF6 generates tris(carbene) dicationic palladium complex 3 in which the iodine ligands are exchanged with SbF6 anions and the metal center is stabilized by one acetonitrile ligand. Complexes 2 and 3 were tested in several cross coupling reactions showing high conversions under low catalyst loadings and mild reaction conditions. Additionally, complexes 2 and 3 performed well in the hydrosilylation of terminal alkynes with good selectivity toward the E-isomer.

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Bright luminescent lithium and magnesium carbene complexes

Abstract: We report on the convenient synthesis of a CNC pincer ligand com¬po-sed of car¬ba¬zole and two mesoionic carbenes, as well as the corresponding lithium- and magnesium complexes. Mono-deprotonation affords a...

Cited by 28 publications

References 149 publications

Chemistry of Compounds Based on 1,2,3-Triazolylidene-Type Mesoionic Carbenes

Chemistry of Compounds Based on 1,2,3-Triazolylidene-Type Mesoionic Carbenes

Mesoionic Carbenes in Low- to High-Valent Vanadium Chemistry

Palladium(II) Complexes of a Neutral CCC-Tris(N-heterocyclic carbene) Pincer Ligand: Synthesis and Catalytic Applications

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