A complex with nitrogen single, double, and triple bonds to the same chromium atom: synthesis, structure, and reactivity

Beaumier, Evan P.; Billow, Brennan S.; Singh, Amrendra K.; Biros, Shannon M.; Odom, Aaron L.

doi:10.1039/c5sc04608d

Cited by 22 publications

(34 citation statements)

References 25 publications

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“…By 14 N NMR spectroscopy, the NCr(N- i -Pr 2 ) 2 X compounds generally exhibit two distinct peaks in the 14 N spectrum. , A broad signal downfield, in the range of 900–1100 ppm, correlates to the nitrido nitrogen, and a sharper signal typically in the 100–300 ppm range correlates to the diisopropylamido nitrogens. Our group previously reported the 14 N NMR chemical shifts of NCr(N i Pr 2 )(NPh) ( CrN123 ), which bears nominally single, double, and triple bonds between nitrogen and Cr(VI) . In this complex, the N–Cr amido, imido, and nitrido chemical shifts are found at 214.33, 559.6, and 963.25 ppm, respectively.…”

Section: Results and Discussionsupporting

confidence: 65%

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Weakly Coordinating yet Ion Paired: Anion Effects on an Internal Rearrangement

et al. 2017

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“Weakly coordinating anions” such as tetraarylborates are ubiquitous in applications of inorganic and organometallic chemistry, with great industrial importance. In this work, we probe the ion-pairing ability of these weakly coordinating anions using the highly sensitive chromium(VI) nitrido bis(diisopropylamido) system NCr(N-i-Pr2)2X, with one variable coordination site (X). This system is being used in the quantification of ligand donor ability to high-valent metal centers and has simply been called the ligand donor parameter (LDP). The donor ability of the variable ligand can be measured by solution-state rotational barrier studies via NMR spectroscopy. If the variable ligand is neutral, the chromium complex is cationic, {NCr(N-i-Pr2)2L}+, with its pendant anion. Despite the weakly coordinating nature of the counteranions employed, a significant amount of ion pairing has been noted in solution, the result of which is substantial enough to perturb the sensitive LDP measurement. These effects have been noted for many commonly used counteranions, including hexafluoroantimonate(V), hexafluorophosphate(V), tetraphenylborate, and tetrakis(bis(3,5-trifluoromethyl)phenyl)borate (BArF24). Using diffusion ordered (DOSY) and rotating-frame Overhauser effect (ROESY) NMR spectroscopy and LDP values, we have shown, predictably, that the extent of ion pairing is solvent dependent and appears to be minimized by increasing the dielectric constant of the NMR solvent utilized. Additionally, we have gained insight into differences in the nature of ion pairing dependent upon the identity of the weakly coordinating anion employed. It was found that the tetraarylborate anions appear to be fully ion paired in CDCl3 but affect amido rotation less in comparison to other anions. We postulate that the smaller effect on the internal rearrangement by these fluorinated tetraarylborate anions is due to a lack of specificity in the interaction with the cation rather than a lack of ion pairing, which may be a general feature of these anions.

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Section: Results and Discussionsupporting

confidence: 65%

“…Our group previously reported the 14 N NMR chemical shifts of NCr(N i Pr 2 )(NPh) (CrN123), which bears nominally single, double, and triple bonds between nitrogen and Cr(VI). 20 In this complex, the N−Cr amido, imido, and nitrido chemical shifts are found at 214.33, 559.6, and 963.25 ppm, respectively.…”

Section: ■ Results and Discussionmentioning

confidence: 86%

Weakly Coordinating yet Ion Paired: Anion Effects on an Internal Rearrangement

et al. 2017

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“… Structures of Schrock and Clark’s “yl-ene-yne” complex of refs ( 41 , 42 ), Wilkinson’s nitride-imido complex (half of the dimer is shown and the chloride bridges to one lithium of a chemically equivalent manganese center) of ref ( 46 ), and the NCr(NPh) (NPr i 2 ) 2 anion of ref ( 43 ). Reprinted with permission from ref ( 43 ). Copyright 2016 PCCP Owner Societies.…”

Section: Introductionmentioning

confidence: 99%

Metal Ion Modeling Using Classical Mechanics

2017

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Metal ions play significant roles in numerous fields including chemistry, geochemistry, biochemistry, and materials science. With computational tools increasingly becoming important in chemical research, methods have emerged to effectively face the challenge of modeling metal ions in the gas, aqueous, and solid phases. Herein, we review both quantum and classical modeling strategies for metal ion-containing systems that have been developed over the past few decades. This Review focuses on classical metal ion modeling based on unpolarized models (including the nonbonded, bonded, cationic dummy atom, and combined models), polarizable models (e.g., the fluctuating charge, Drude oscillator, and the induced dipole models), the angular overlap model, and valence bond-based models. Quantum mechanical studies of metal ion-containing systems at the semiempirical, ab initio, and density functional levels of theory are reviewed as well with a particular focus on how these methods inform classical modeling efforts. Finally, conclusions and future prospects and directions are offered that will further enhance the classical modeling of metal ion-containing systems.

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“…The LOD for Cr 3+ just equals the current limit of 2 µM suggested by WHO for drinking water, whereas the LOD for Cu 2+ is well below the current limit of 30 µM. The different behaviors of N-CQDs-40 min and N-CQDs-15 h with respect to Cr 3+ and Cu 2+ can be correlated with the larger presence of amine groups on N-CQDs-15 h, which may have given a more specific interaction, i.e., a larger affinity toward N-derivatives as compared to the other probed ions, such as in Reinecke's salt (NH 4 [Cr(NCS) 4 (NH 3 ) 2 ]•H 2 O) or other stable Cr 3+ complexes with N-derivatives, which can form with multiple bonds [54]. Similarly, Cu 2+ may undergo a substitution of oxygen-dented ligands bonded to Cu 2+ by nitrogen-dented ones [55], thus shifting the selectivity as well.…”

Section: Selectivity Of the N-cqds As A Probe For Heavy Metal Detectionmentioning

confidence: 99%

Top-Down N-Doped Carbon Quantum Dots for Multiple Purposes: Heavy Metal Detection and Intracellular Fluorescence

et al. 2021

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In the present study, we successfully synthesized N-doped carbon quantum dots (N-CQDs) using a top-down approach, i.e., hydroxyl radical opening of fullerene with hydrogen peroxide, in basic ambient using ammonia for two different reaction times. The ensuing characterization via dynamic light scattering, SEM, and IR spectroscopy revealed a size control that was dependent on the reaction time, as well as a more pronounced -NH2 functionalization. The N-CQDs were probed for metal ion detection in aqueous solutions and during bioimaging and displayed a Cr3+ and Cu2+ selectivity shift at a higher degree of -NH2 functionalization, as well as HEK-293 cell nuclei marking.

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A complex with nitrogen single, double, and triple bonds to the same chromium atom: synthesis, structure, and reactivity

Abstract: A complex with single, double and triple bonds between nitrogen and the same metal center has been synthesized, [NCr(NPh)(NPri2)2]–. The complex shows differential activity, with some electrophiles attacking the imido and others the nitrido.

Cited by 22 publications

References 25 publications

Weakly Coordinating yet Ion Paired: Anion Effects on an Internal Rearrangement

Weakly Coordinating yet Ion Paired: Anion Effects on an Internal Rearrangement

Metal Ion Modeling Using Classical Mechanics

Top-Down N-Doped Carbon Quantum Dots for Multiple Purposes: Heavy Metal Detection and Intracellular Fluorescence

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