Electron‐Deficient Imidazolium Substituted Cp Ligands and their Ru Complexes

Mazzotta, Fabio; Zitzer, Georg; Speiser, Bernd; Kunz, Doris

doi:10.1002/chem.202002801

Cited by 7 publications

(30 citation statements)

References 84 publications

(163 reference statements)

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“…The X-ray structure analysis of a single crystal obtained from the reaction mixture by overlaying with pentane confirms the metallocene 4·NTf 2 as the product (Scheme ). It is advantageous to add the Li salt in a second step after formation of the metallocene 4[Sc(OTf) 4 (thf) 2 ] ; otherwise, the reaction takes several days to complete, which is possibly due to the initial coordination of 1 to LiNTf 2 . , …”

Section: Resultsmentioning

confidence: 99%

“…With at least one cationic substituent directly attached to the Cp moiety, the donor strength is reduced in comparison to unsubstituted Cp. 20,21 This can lead to stability problems in the presence of coordinating solvents. In the past, we introduced several C-ylidic Cp ligands and used imidazolium moieties to stabilize the cationic charge attached to the Cp: for example, in ligand 1.…”

Section: ■ Introductionmentioning

confidence: 90%

“…In the past, we introduced several C-ylidic Cp ligands and used imidazolium moieties to stabilize the cationic charge attached to the Cp: for example, in ligand 1. 21,22 Furthermore, the Cp-like reactivity was confirmed and the donor properties were elucidated. 20,21 The coordination of the ylidic Cp ligand can be achieved either by simple addition to the metal center or by substitution of a neutral or anionic ligand.…”

Section: ■ Introductionmentioning

confidence: 91%

“…Elemental analyses were determined using a varioMICRO cube by the elemental analysis section of the Institut für Anorganische Chemie at the University of Tübingen. 1 and [ScCl 3 (thf) 3 ] were synthesized according to the published procedure. [Sc(OTf) 3 ] was purchased and dried for 48 h at 150 °C and 10 –5 mbar.…”

Section: Experimental Sectionmentioning

confidence: 99%

“…A – C − and 1 (Scheme ), are a very interesting class of electron-poor Cp ligands. With at least one cationic substituent directly attached to the Cp moiety, the donor strength is reduced in comparison to unsubstituted Cp. , This can lead to stability problems in the presence of coordinating solvents. In the past, we introduced several C -ylidic Cp ligands and used imidazolium moieties to stabilize the cationic charge attached to the Cp: for example, in ligand 1 . , Furthermore, the Cp-like reactivity was confirmed and the donor properties were elucidated. , The coordination of the ylidic Cp ligand can be achieved either by simple addition to the metal center or by substitution of a neutral or anionic ligand.…”

Section: Introductionmentioning

confidence: 99%

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An Ylidic Cp and its Scandium Complexes in Equilibrium

Mazzotta

Kunz

2021

Organometallics

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Scandium complexes bearing a C-ylidic, electron-deficient Cp ligand are presented by starting from [ScCl 3 (thf) 3 ]. As ylidic ligands do not require salt metathesis, the coordination of the Cp ligand is realized by mere substitution of the tetrahydrofuran ligands. In acetonitrile an equilibrium among the free ligand, the half-sandwich complex, and the cationic metallocene with its tetrachloridoscandate counterion is observed via NMR spectroscopy. This equilibrium is fully confirmed by 1 H and 45 Sc NMR EXSY experiments. In the absence of coordinating solvents, the selective formation of all compounds of the equilibrium has been achieved, and the structures have been confirmed by NMR spectroscopy and X-ray structure analysis. Especially 45 Sc NMR spectroscopy reveals signals with characteristic chemical shifts for the half-sandwich complex and the metallocene. With scandium triflate the corresponding scandocene is also accessible.

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Section: Resultsmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 90%

Section: ■ Introductionmentioning

confidence: 91%

Section: Experimental Sectionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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An Ylidic Cp and its Scandium Complexes in Equilibrium

Mazzotta

Kunz

2021

Organometallics

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Phosphonium‐substituted Diphosphaindenylide (PPI): Exploration of Biradical Character and Ligand Properties

Coburger,

Zuber,

Schweinzer

et al. 2024

Chemistry A European J

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Starting from C6H4(PCl2)2 and the TMS‐substituted ylide (TMS)2C=PR3 (TMS = trimethylsilyl, R = p‐tolyl), the phosphonium‐substituted diphosphaindenylide PPI was prepared in two steps. CASSCF calculations as well as the reactivity toward diphenyl acetylene suggest a notable biradical character in PPI. Reaction with [Cr(CO)3(MeCN)3] affords the complex [Cr(CO)3(η5‐PPI)] (5). This complex was employed to explore the ligand properties of PPI, which demonstrates considerable potential through the combination of strong metal‐ligand interactions and the possibility of a pronounced indenyl effect.

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IZCp and PZCp: Redox Non-innocent Cyclopentadienyl Ligands as Electron Reservoirs for Sandwich Complexes

Choi,

Yoo,

Song

et al. 2024

Inorg. Chem.

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A long-sustained effort of systematic steric and electronic modification of cyclopentadienyl (Cp) ligands has enabled them to find wide-ranging, valuable applications. Herein, we present two novel Cp ligands: imidazolium- and pyrrolinium-substituted zwitterionic Cps (IZCp and PZCp), whose key utility is redox non-innocencethe ability to participate cooperatively with the metal center in redox reactions. Through the simple metalation of ZCps, the Cr(0) and Mo(0) half-sandwich complexes (IZCp)Cr(CO)3, (PZCp)Cr(CO)3, (IZCp)Mo(CO)3, and (PZCp)Mo(CO)3, respectively, as well as the Ru(II) sandwich complexes [(IZCp)RuCp]PF6 and [(PZCp)RuCp]PF6 were prepared. The sandwich complexes were fully characterized and showed by cyclic voltammetry reversible one-electron reduction at E 1/2 potentials ranging from −1.7 to −2.7 V vs Fc/Fc+. These values are unusually low and have not been observed with other Cp ligands due to the instability of the reduced complexes. Density functional theory (DFT) calculations for the reduced sandwich derivatives with IZCp and PZCp showed their spin densities to be highly delocalized over their ZCp ligand moieties (70–90%). Electron paramagnetic resonance (EPR) analysis of the isolated K[(PZCp)Mo(CO)3] and (PZCp)RuCp also indicated a high degree of ligand-localized radical character. Thus, the IZCp and PZCp ligands act as electron reservoirs to sustain these sandwich complexes in highly reduced states. At the same time, the CO stretching frequencies of K[(PZCp)Mo(CO)3]: νCO 1871, 1748, and 1699 cm–1, rank the [PZCp]− ligand as the strongest electron-donating Cp ligand among the reported CpMo(CO)3 derivatives, whose νCO > 1746 cm–1. In addition, these redox non-innocent Cps were obtained in high yields and found to be practically air- and moisture-stable, unlike typical Cps.

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Electron‐Deficient Imidazolium Substituted Cp Ligands and their Ru Complexes

Cited by 7 publications

References 84 publications

An Ylidic Cp and its Scandium Complexes in Equilibrium

An Ylidic Cp and its Scandium Complexes in Equilibrium

Phosphonium‐substituted Diphosphaindenylide (PPI): Exploration of Biradical Character and Ligand Properties

IZCp and PZCp: Redox Non-innocent Cyclopentadienyl Ligands as Electron Reservoirs for Sandwich Complexes

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