Experimental and DFT Evidence for the Fractional Non‐Innocence of a β‐Diketonate Ligand

Das, Amit; Scherer, Thomas M.; Mondal, Prasenjit; Mobin, Shaikh M.; Kaim, Wolfgang; Lahiri, Goutam Kumar

doi:10.1002/chem.201201785

Cited by 35 publications

(22 citation statements)

References 51 publications

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“…Hopo and the three Fe III , Cu II , and Zn II complexes were studied through cyclic voltammetry in parallel with the corresponding acac derivatives. Hopo and the complexes can be reduced twice in the range from −1 to −2.5 V (Figure 5) in line with previous observation on Hopo and opo complexes [1,11,15,16,25,[44][45][46][47][48]57,59,62,67] while oxidation was not observed in the range of 0.0 to 3.0 V (Table 1).…”

Section: Electrochemistrysupporting

confidence: 92%

“…Since about 2010, researchers have recognised the enormous potential of the so-called non-innocent ligand opo − with its high similarity to the o-semiquinones (Scheme 1) [18,[44][45][46][47][48]. In complexes of non-innocent ligands, the ligands can have variable charges and oxidation states, thus making the metal oxidation state ambiguous [18].…”

Section: Introductionmentioning

confidence: 99%

“…In complexes of non-innocent ligands, the ligands can have variable charges and oxidation states, thus making the metal oxidation state ambiguous [18]. Opo complexes of main-group and transition metals are therefore intensely studied for their magnetic, electron-and chargetransfer phenomena [44][45][46][47][48][49][50][51][52][53][54][55] as well as for their use in electroactive materials [51][52][53][54][55][56][57][58][59] or in electron transfer or related catalysis [53,55,57,[60][61][62][63][64][65][66][67][68][69][70].…”

Section: Introductionmentioning

confidence: 99%

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FeIII, CuII and ZnII Complexes of the Rigid 9-Oxido-phenalenone Ligand—Spectroscopy, Electrochemistry, and Cytotoxic Properties

Butsch

Haseloer

Schmitz

et al. 2021

IJMS

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The three complexes [Fe(opo)3], [Cu(opo)2], and [Zn(opo)2] containing the non-innocent anionic ligand opo− (opo− = 9-oxido-phenalenone, Hopo = 9-hydroxyphenalonone) were synthesised from the corresponding acetylacetonates. [Zn(opo)2] was characterised using 1H nuclear magnetic resonance (NMR) spectroscopy, the paramagnetic [Fe(opo)3] and [Cu(opo)2] by electron paramagnetic resonance (EPR) spectroscopy. While the EPR spectra of [Cu(opo)2] and [Cu(acac)2] in dimethylformamide (DMF) solution are very similar, a rather narrow spectrum was observed for [Fe(opo)3] in tetrahydrofuran (THF) solution in contrast to the very broad spectrum of [Fe(acac)3] in THF (Hacac = acetylacetone, 2,4-pentanedione; acac− = acetylacetonate). The narrow, completely isotropic signal of [Fe(opo)3] disagrees with a metal-centred S = 5/2 spin system that is observed in the solid state. We assume spin-delocalisation to the opo ligand in the sense of an opo− to FeIII electron transfer. All compounds show several electrochemical opo-centred reduction waves in the range of −1 to −3 V vs. the ferrocene/ferrocenium couple. However, for CuII and FeIII the very first one-electron reductions are metal-centred. Electronic absorption in the UV to vis range are due to π–π* transitions in the opo core, giving Hopo and [Zn(opo)2] a yellow to orange colour. The structured bands ranging from 400 to 500 for all compounds are assigned to the lowest energy π−π* transitions. They show markedly higher intensities and slight shifts for the CuII (brown) and FeIII (red) complexes and we assume admixing metal contributions (MLCT for CuII, LMCT for FeIII). For both complexes long-wavelength absorptions assignable to d–d transitions were detected. Detailed spectroelectrochemical experiments confirm both the electrochemical and the optical assignments. Hopo and the complexes [Cu(opo)2], [Zn(opo)2], and [Fe(opo)3] show antiproliferative activities against HT-29 (colon cancer) and MCF-7 (breast cancer) cell lines in the range of a few µM, comparable to cisplatin under the same conditions.

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Section: Electrochemistrysupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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FeIII, CuII and ZnII Complexes of the Rigid 9-Oxido-phenalenone Ligand—Spectroscopy, Electrochemistry, and Cytotoxic Properties

Butsch

Haseloer

Schmitz

et al. 2021

IJMS

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“…region in CH 3 CN (Figure , Experimental Section) and the band position/intensity varied to some extent based on the nature and binding mode of the transformed L 1 ‐L 6 with the metal ions including isomeric identities of the complexes. The origin of the transitions were evaluated by time‐dependent DFT (TD‐DFT) calculations (Table S38, Supporting Information) which revealed (π * )L or (π * )PPh 3 targeted mixed metal‐ligand to ligand based M/LLCT transitions in the visible region (633‐510 nm) due to metal‐ligand covalency besides intra‐ligand/inter‐ligand π‐π * transitions in the higher energy UV‐region.…”

Section: Resultsmentioning

confidence: 99%

Ruthenium‐Hydride Assisted Remarkable Diversity Towards Non‐Spectator Feature of Benzodifuroxan

Dey

Panda

Lahiri

2020

Chemistry An Asian Journal

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The present article demonstrates that rutheniumhydride [Ru II (H)(Cl)(CO)(PPh 3) 3 ] mediated diverse functionalization modes of benzodifuroxan (BDF) encompassing two furoxan rings. Hydride transfer from the metal precursor facilitated multiple cascade reactions involving unsymmetrical cleavage of the furoxan rings of BDF, leading to the onepot formation of a series of ruthenium (II) coordinated functionalized ligands exhibiting bidentate k 2-N,O, k 2-N,N' and bis-bidentate μ-bis(k 2-N,O) modes. Further, a moderately stable intermediate species was also encountered in the reaction sequence in which the transformed deoxygenated ligand coordinated to the metal ion via the rarely manifested furazan ring (k 2-N,N'' mode). The products were authenticated by their single-crystal X-ray structures and other spectroscopic/analytical techniques. Redox non-innocence of the functionalized ligands in the complexes was illustrated by spectroelectrochemistry (cyclic voltammmetry, UV-Vis. and EPR) in conjunction with DFT/TD-DFT calculations. Mechanistic outline for the facile ring opening processes of BDF including interconversions of complexes (e. g. reductive ring opening) were also addressed.

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“…A collective consideration of molecular orbital (MO) compositions (see Tables S3–S12 in the Supporting Information) revealed metal‐based oxidation with an appreciable contribution from L 1 and metal‐based reduction, leading to the primary electronic structural forms of [Ru IV (acac) 2 (L 1 ) − ] + ( S= 0)/antiferromagnetically coupled [Ru III (acac) 2 (L 1. )] + ( S= 0) and [Ru II (acac) 2 (L 1 ) − ] − ( S= 0) for 1 + and 1 − , respectively (Scheme ), which implied the fractional noninnocent potential of L 1 …”

Section: Resultsmentioning

confidence: 99%

Solvent‐Mediated Functionalization of Benzofuroxan on Electron‐Rich Ruthenium Complex Platform

Ghosh

Dey

Panda

et al. 2018

Chemistry An Asian Journal

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An unprecedented reactivity profile of biochemically relevant R-benzofuroxan (R=H, Me, Cl), with high structural diversity and molecular complexity on a selective {Ru(acac) } (acac=acetylacetonate) platform, in conjugation with EtOH solvent mediation, is revealed. This led to the development of monomeric [Ru (acac) (L )] (1 a-1 c; L =2-nitrosoanilido derivatives) and dimeric [{Ru (acac) } (L )] (2 a-2 b; L =(1E,2E)-N ,N -bis(2-nitrosophenyl)ethane-1,2-diimine derivatives) complexes in one pot with a change in the metal redox conditions. The functionalization of benzofuroxan in 1 and 2 implied in situ reduction of N=O to NH in the former and solvent-assisted multiple N-C coupling in the latter. The aforesaid transformation processes were authenticated through structural elucidation of representative complexes, and evaluated by their spectroscopic/electrochemical features, along with C D OD labeling and monitoring of the impact of substituents (R) in the benzofuroxan framework on the product distribution process. The noninnocent potential of newly developed L and L in 1 and 2, respectively, was also probed by spectroelectrochemistry in combination with DFT calculations.

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Experimental and DFT Evidence for the Fractional Non‐Innocence of a β‐Diketonate Ligand

Cited by 35 publications

References 51 publications

FeIII, CuII and ZnII Complexes of the Rigid 9-Oxido-phenalenone Ligand—Spectroscopy, Electrochemistry, and Cytotoxic Properties

FeIII, CuII and ZnII Complexes of the Rigid 9-Oxido-phenalenone Ligand—Spectroscopy, Electrochemistry, and Cytotoxic Properties

Ruthenium‐Hydride Assisted Remarkable Diversity Towards Non‐Spectator Feature of Benzodifuroxan

Solvent‐Mediated Functionalization of Benzofuroxan on Electron‐Rich Ruthenium Complex Platform

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