Spectroscopic characterization of a Ru(<scp>iii</scp>)-OCl intermediate: a structural mimic of haloperoxidase enzymes

Kumar, Ramayya; Awasthi, Ayushi; Gupta, Sikha; Eerlapally, Raju; Draksharapu, Apparao

doi:10.1039/d2dt01947g

Cited by 5 publications

(16 citation statements)

References 37 publications

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“…S12 and S13 †). 23,27 A vibrational band at 2270 cm −1 in the IR spectrum (Fig. S14A †) affirms the bound acetonitrile ligand at the sixth site which fits well with the computationally optimised structure (Fig.…”

Section: Dalton Transactions Papersupporting

confidence: 72%

“…The average Ru-N bond distance of 2.066 Å illustrates a Ru II low spin complex. 23,25,26 The 1 H NMR spectrum of 4 recorded in CD 3 CN revealed signals in the 1-10 ppm range, confirming the low spin nature of the Ru II centre in the solution (Fig. S12 and S13 †).…”

Section: Dalton Transactions Papermentioning

confidence: 67%

“…The reported [(L)Ru III -OCl] 2+ species serves as the structural model for haloperoxidases. 23 However, in the present case with two (L)Ru II complexes 1 and 4, it was interesting to witness the generation of a [(L)Ru III -OCl] 2+ species carried out by modeling naturally occurring heme-dependent haloperoxidases. The appealing part of the mechanism has been the influence of the Cl − ion in the reaction of mCPBA with (L)Ru II to form a [(L)Ru III -OCl] 2+ species eventually.…”

Section: Discussionmentioning

confidence: 94%

“…Moreover, the formation of 2 from 1 with NaOCl requires the presence of HClO 4 , which is absent in the present case. 23 To verify the versatility of the formation of the transient Ru III -OCl species in the ways described before, we have synthesized a [(MeTPEN)Ru II (NCCH 3 )](PF 6 ) 2 ( 4) complex. The synthesis of 4 was carried out according to the procedure reported for 1.…”

Section: Dalton Transactions Papermentioning

confidence: 99%

“…This reactivity pattern with phenol and its derivatives suggests that 5 is electrophilic, like 2. 23 A proposed mechanism for the formation of the Ru III -OCl species (2 and 5) from the reaction of the Ru II precursor complexes (1 and 4) with mCPBA and NaCl is shown in Scheme 2. The reaction of mCPBA with Ru II complexes resulted in the formation of a putative Ru V vO species (3 and 6).…”

Section: Dalton Transactions Papermentioning

confidence: 99%

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Generation of Ru(iii)-hypochlorite with resemblance to the heme-dependent haloperoxidase enzyme

Kumar,

Ahsan,

Awasthi

et al. 2023

Dalton Trans.

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Section: Dalton Transactions Papersupporting

confidence: 72%

Section: Dalton Transactions Papermentioning

confidence: 67%

Section: Discussionmentioning

confidence: 94%

Section: Dalton Transactions Papermentioning

confidence: 99%

Section: Dalton Transactions Papermentioning

confidence: 99%

See 3 more Smart Citations

Generation of Ru(iii)-hypochlorite with resemblance to the heme-dependent haloperoxidase enzyme

Kumar,

Ahsan,

Awasthi

et al. 2023

Dalton Trans.

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Mn(II) Polypyridyl Complexes: Precursors to High Valent Mn(V)=O Species and Inhibitors of Cancer Cell Proliferation

Arora

Gupta

Vechalapu

et al. 2023

Chemistry A European J

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The reaction of [(L)MnII]2+ (L = neutral polypyridine ligand framework) in the presence of mCPBA (m‐chloroperoxybenzoic acid) generates a putative Mn(V)=O species at RT. The proposed Mn(V)=O species is capable of performing the aromatic hydroxylation of Cl‐benzoic acid derived from mCPBA to give [(L)MnIII(m‐Cl‐salicylate)]+, which in the presence of excess mCPBA generates a metastable [(L)MnV(O)(m‐Cl‐salicylate)]+, characterized by UV/Vis absorption, EPR, resonance Raman spectroscopy, and ESI‐MS studies. The current study highlights the fact that [(L)MnIII(m‐Cl‐salicylate)]+ formation may not be a dead end for catalysis. Further, a plausible mechanism has been proposed for the formation of [(L)MnV(O)‐m‐Cl‐salicylate)]+ from [(L)MnIII(m‐Clsalicylate)]+. The characterized transient [(L)MnV(O)‐m‐Cl‐salicylate)]+ reported in the current work exhibits high reactivity for oxygen atom transfer reactions, supported by the electrophilic character depicted from Hammett studies using a series of para‐substituted thioanisoles. The unprecedented study starting from a non‐heme neutral polypyridine ligand framework paves a path for mimicking the natural active site of photosystem II under ambient conditions. Finally, evaluating the intracellular effect of Mn(II) complexes revealed an enhanced intracellular ROS and mitochondrial dysfunction to prevent the proliferation of hepatocellular carcinoma and breast cancer cells.

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Altering the Localization of an Unpaired Spin in a Formal Ni(V) Species

Awasthi,

Mallojjala,

Kumar

et al. 2023

Chemistry A European J

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The participation of both ligand and the metal center in the redox events has been recognized as one of the ways to attain the formal high valent complexes for the late 3d metals, such as Ni and Cu. Such an approach has been employed successfully to stabilize a Ni(III) bisphenoxyl diradical species in which there exist an equilibrium between the ligand and the Ni localized resultant spin. The present work however broadens the scope of the previously reported three oxidized equivalent species by conveying the approaches that tend to affect the reported equilibrium in CH3CN at 233 K. Various spectroscopic characterization revealed that employing exogenous N‐donor ligands like 1‐methyl imidazole and pyridine favors the formation of the Ni centered localized spin though axial binding. In contrast, due to its steric hinderance, quinoline favors an exclusive ligand localized radical species. DFT studies shed light on the novel intermediates' complex electronic structure. Further, the three oxidized equivalent species with the Ni centered spin was examined for its hydrogen atom abstraction ability stressing their key role in alike reactions.

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Spectroscopic characterization of a Ru(iii)-OCl intermediate: a structural mimic of haloperoxidase enzymes

Abstract: Haloperoxidase enzymes utilize metal hypohalite species to halogenate aliphatic and aromatic C–H bonds to C–X (X = Cl, Br, I) in nature. In this work, we report the synthesis and...

Cited by 5 publications

References 37 publications

Generation of Ru(iii)-hypochlorite with resemblance to the heme-dependent haloperoxidase enzyme

Generation of Ru(iii)-hypochlorite with resemblance to the heme-dependent haloperoxidase enzyme

Mn(II) Polypyridyl Complexes: Precursors to High Valent Mn(V)=O Species and Inhibitors of Cancer Cell Proliferation

Altering the Localization of an Unpaired Spin in a Formal Ni(V) Species

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