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A binuclear Co(II) complex, [Co2(PhBIMP)(μ‐O2CPh)(MeCN)]2+ (1) (PhBIMP is the anion of 2,6‐bis[(bis((N‐1‐methyl‐4,5‐diphenylimidazoylmethyl) amino)methyl]‐4‐methylphenol) catalyzes the hydrolysis of thiolates to the corresponding alcohols/phenols at room temperature. Hydrolysis of 11 different thiolates has been investigated with a catalyst loading of 4–6.7 mol% and with the highest TON values reaching 22. Furthermore, the effects of electron donating and electron withdrawing groups on the bridging benzoate of 1 have been investigated. The intermediates, products, and fate of the catalyst have been identified by mass spectrometric, gas chromatographic and gravimetric methods, and based on that, a mechanism for the catalytic cycle has been proposed. [ABSTRACT FROM AUTHOR]

The intriguing chemistry of chalcogen (S, Se)-containing ligands and their capability to bridge multiple metal centres have resulted in a plethora of reports on transition metal complexes featuring hydrosulfide (HS-) and polychalcogenides (En2-, E = S, Se). While a large number of such molecules are strictly organometallic complexes, examples of non-organometallic complexes featuring HS- and En2- with N-/O-donor ligands are relatively rare. The general synthetic procedure for the transition metal-hydrosulfido complexes involves the reaction of the corresponding metal salts with HS-/H2S and this is prone to generate sulfido bridged oligomers in the absence of sterically demanding ligands. On the other hand, the synthetic methods for the preparation of transition metal-polychalcogenido complexes include the reaction of the corresponding metal salts with En2- or the two electron oxidation of low-valent metals with elemental chalcogen, often at an elevated temperature and/or for a long time. Recently, we have developed new synthetic methods for the preparation of two new classes of binuclear transition metal complexes featuring either HS-, or Sn2- and Sen2- ligands. The new method for the synthesis of transition metal-hydrosulfido complexes involved transition metal-mediated hydrolysis of thiolates at room temperature (RT), while the method for the synthesis of transition metal-polychalcogenido complexes involved redox reaction of coordinated thiolates and exogenous elemental chalcogens at RT. An overview of the synthetic aspects, structural properties and intriguing reactivity of these two new classes of transition metal complexes is presented. [ABSTRACT FROM AUTHOR]

This document summarizes a study on the reduction of carbon dioxide (CO2) using a binuclear Ni complex as a catalyst. The researchers found that using heavy water (D2O) instead of regular water (H2O) resulted in a shift in product selectivity, with an increased production of formic acid (HCOOH) and a decrease in the production of carbon monoxide (CO) and hydrogen gas (H2). The study suggests that the mechanism of CO2 reduction involves protonation steps, with the second protonation step being the rate-determining step. The findings highlight the potential for using kinetic isotope effects (KIEs) to control the selectivity of CO2 reduction. [Extracted from the article]

Artificial intelligence (AI) has the potential for vast societal and economic gain; yet applications are developed in a largely ad hoc manner, lacking coherent, standardized, modular, and reusable infrastructures. The NSF‐funded Intelligent CyberInfrastructure with Computational Learning in the Environment AI Institute ("ICICLE") aims to fundamentally advance edge‐to‐center, AI‐as‐a‐Service, achieved through intelligent cyberinfrastructure (CI) that spans the edge‐cloud‐HPC computing continuum, plug‐and‐play next‐generation AI and intelligent CI services, and a commitment to design for broad accessibility and widespread benefit. This design is foundational to the institute's commitment to democratizing AI. The institute's CI activities are informed by three high‐impact domains: animal ecology, digital agriculture, and smart foodsheds. The institute's workforce development and broadening participation in computing efforts reinforce the institute's commitment to democratizing AI. ICICLE seeks to serve as the national nexus for AI and intelligent CI, and welcomes engagement across its wide set of programs. [ABSTRACT FROM AUTHOR]

Comparative reactivity of a series of new Zn(II) and Fe(II) compounds, [(Py2ald)M(ER)] (E = S, R = Ph: M = Zn, 1aZn; M = Fe, 1aFe; E = S, R = 2,6-Me2-C6H3: M = Zn, 1bZn; M = Fe, 1bFe; E = Se, R = Ph: M = Zn, 2Zn; M = Fe, 2Fe), and [(Py2ald)M]22+ (M = Zn, 5Zn; M = Fe, 5Fe) is presented. Compound 1aZn could react with nitrite (NO2−) to produce [(Py2ald)Zn(ONO)] (3Zn), which, upon treatment with thiols and PhSeH (proton source), could regenerate either 1aZn/5Zn and 2Zn respectively, along with the production of nitric oxide (NO) where the yield of NO increases in the order tBuSH ≪ PhCH2SH < PhSH < PhSeH. In contrast to this, 1aFe, 2Fe and 5Fe could affect the direct reduction of NO2− in the absence of protons to generate NO and [{(Py2ald)(ONO)Fe}2-μ2-O] (8Fe). Moreover, 8Fe could regenerate 5Fe and 1aFe/2Fe upon treatment with 4 and 6 equiv. of PhEH (E = S/Se), respectively, along with the generation of NO. Finally, a comparative study of the mononuclear Zn(II) and Fe(II) compounds for the transfer of the coordinated thiolate/selenolate and the generation and transfer of reactive sulfur/selenium species (RES−, E = Se, S) to a series of organic substrates has been provided. [ABSTRACT FROM AUTHOR]

A new mononuclear cobalt(III)‐pentasulfido compound, [(L)Co(S5)] (3) has been synthesized by using a convergent redox reaction between elemental sulfur and two new cobalt(II)‐thiolato compounds, [(L)Co(SR)] (R=Ph, 2 a; 2,6‐Me2‐C6H4, 2 b), which in turn were synthesized from a dimeric cobalt(II) complex, [(L)2Co2]2+ (1). Compound 3 features a low‐spin, diamagnetic, Co(III) center with a coordinated pentasulfido (S52−) chain and has no precedence in the literature. Compound 3 is highly stable towards reduction with a potential of −1.36 V (vs. Cp2Fe+/Cp2Fe) and gives back 1 upon chemical/electrochemical reduction. Reaction of 3 with phosphines yields back 1 and phosphine sulfides, while protonation of the coordinated S52− chain in 3 leads to the formation of 1, elemental sulfur and H2S. Finally, transfer of the coordinated S52− chain in 3 to selected organic compounds, such as MeI, PhCH2Br and PhCOCl, for the generation of organopolysulfido compounds has been demonstrated. [ABSTRACT FROM AUTHOR]

The synthesis and characterization of a series of new binuclear Zn(II) complexes bearing (i) terminal H2O/OH, (ii) bridging thiolates, (iii) bridging thiocarboxylates, (iv) bridging carboxylates, and (v) bridging carboxylate bearing free thiol groups are presented. Unlike the previously reported Co(II) and Fe(II) mediated desulfurization of thiolates to yield binuclear Co(II)/Fe(II)-hydrosulfide complexes by us (Jana et al., Inorg. Chem., 2018, 57, 617; Pal et al., Dalton Trans., 2019, 48, 5903), Zn(II) was found to be incapable of mediating the C–S bond cleavage of thiolates and thus allowed the isolation of binuclear Zn(II)–thiolate complexes. These binuclear Zn(II)–thiolate complexes were further examined for chemical oxidation of the coordinated thiolates and insertion of neutral sulfur into the Zn(II)–thiolate bonds. Interestingly, the latter reactivity study demonstrated the formation of a new binuclear Zn(II) complex featuring a bridging S32− unit which was generated via a redox reaction involving the bridging thiolates and the externally added elemental sulfur. [ABSTRACT FROM AUTHOR]

Reduction of nitric oxide (NO) to nitrous oxide (N2O) is associated with immense biological and health implications. Flavodiiron nitric oxide reductases (FNORs) are diiron containing enzymes that catalyze the two electron reduction of NO to N2O and help certain pathogenic bacteria to survive under "nitrosative stress" in anaerobic growth conditions. Consequently, invading bacteria can proliferate inside the body of mammals by bypassing the immune defense mechanism involving NO and may thus lead to harmful infections. Various mechanisms, namely the direct reduction, semireduction, superreduction and hyponitrite mechanisms, have been proposed over time for catalytic NO reduction by FNORs. Model studies in relation to the diiron active site of FNORs have immensely helped to replicate the minimal structure–reactivity relationship and to understand the mechanism of NO reduction. A brief overview of the FNOR activity and the proposed reaction mechanisms followed by a systematic description and detailed analysis of the model studies is presented, which describes the development in the area of NO reduction by diiron complexes and its implications. A great deal of successful modeling chemistry as well as the shortcomings related to the synthesis and reactivity studies is discussed in detail. Finally, future prospects in this particular area of research are proposed, which in due course may bring more clarity in the understanding of this important redox reaction. [ABSTRACT FROM AUTHOR]

Introduction: Enterococci are usually normal human commensal of gastrointestinal tract predominantly. They are considered as an important nosocomial pathogen now a day due to its intrinsic as well as increasing acquired antibiotic resistance resulting in a great threat to modern Medicine. Aim: To determine prevalence of Enterococci isolated from clinical specimens with special reference to its virulence and antibiogram conventionally. Materials and Methods: A cross-sectional observational study was conducted over a period of two years (January 2019 to December 2020) with 326 Enterococci, isolated from various clinical specimens received by Department of Microbiology. Enterococci isolated from stool samples were excluded. They were identified and speciated conventionally as per standard laboratory protocol. Gelatinase, haemolysin and biofilm formation was determined for each isolate. Their antibiogram was also determined by disc diffusion methods over Blood agar followed by Minimum Inhibitory Concentration (MIC) testing (as per Clinical and Laboratory Standards Institute (CLSI) guideline). All statistical analysis was done by Chi-square test using Software Statistical Package for the Social Sciences (SPSS) version 22.0. Results: Among the total 4516 samples collected, growth of Enterococci was noted in 7.22% cases. Out of them, E. faecalis (84.05%) out numbered E. faecium. Urine was the most predominant (55.22%) sample. 73.93% isolates produced biofilm whereas 18.40% produced haemolysin and 19.94% produced gelatinase. Most of the isolates were susceptible to vancomycin (94.79%) and linezolid (98.77%). High level gentamicin resistance was seen in 54.6% cases. Ciprofloxacin was the most resistant antibiotic. Vancomycin Resistance Enterococcus (VRE) was detected in 5.21% cases only, out of which Van A type was detected phenotypically in most cases. Conclusion: The high rate of resistance to high-level gentamicin could fail treatment of gentamicin in combination with penicillin group of antibiotics. In clinical samples, the emergence of VRE strains makes treatment options more challenging. [ABSTRACT FROM AUTHOR]

A new electron, six-electron, sulfide-bicapped trinuclear [Mo.sup.IV] cluster containing all sulfur coordination where each Mo atom is seven coordinated and retains the oxidation state of +14 is described. The formation of a binuclear tungsten(V) complex under identical reaction conditions with one electron oxidation of each [W.sup.IV] center and the redox chemistry of these complexes are rationalized.

Complexes analogous to the active site of dissimilatory nitrate reductase from Desulfovibrio desulfuricans are prepared. The NO evolution or nitrosylation to the Fe-S cluster is known from perplasmic nitrate reductase isolated from Pseudomonas dentrificans.

The synthesis, characterization and comparative chemical and structural analyses of a new series of dimeric bis(dithiolene) Mo(IV) and W(IV) complexes and one monomeric bis(dithiolene) tungsten bis(thiophenolate) complex are described. The pH-dependent interconversion has shown that even the pentacoordinated Mo(IV) and W(IV) bis(dithiolene) moieties are forced to dimerize and they can be reverted back to the corresponding monomeric complex.

While the attempted synthesis of diiron(ii)–hydrosulfide complexes using HS− produced an insoluble precipitate, the reaction of Fe(BF4)2·6H2O, Et3N and HN-Et-HPTB with RSH (R = tBu, CH2Ph) yielded the desired complex, [Fe2(N-Et-HPTB)(SH)(H2O)](BF4)2 (1a). The synthesis, one electron oxidation and dioxygen activity of 1a in comparison with an analogous chloride complex, [Fe2(N-Et-HPTB)(Cl)(DMF)2](BF4)2 (2), are described. [ABSTRACT FROM AUTHOR]

The oxidized structure as [Mo(super IV)(OH(sub x))(S.Cys)(S2pd)(sub 2)] (x=1or 2) was established by X-ray crystallography. It is demonstrated that the nitrate is first bound to the molybdenum of the reduced cofactor with the formation of an enzyme substrate complex followed by the essential oxotransfer and the elimination of nitrite ion with the formation of oxidized oxomolybdenum cofactor [Mo(super IV)(O)(S.Cys)(S2pd)(sub 2)].

Carboxylate-bridged nonheme diiron(II) complexes, bearing free functional groups in general, and free thiol groups in particular, were sought. While the addition of sodium γ-hydroxybutyrate into a mixture of Fe(BF4)26H2O, HN-Et-HPTB, and Et3N afforded the complex [Fe2(N-Et-HPTB)(μ-O2C-(CH2)3-OH)](BF4)2 (2) (where N-Et-HPTB is the anion of N,N,N',N'-tetrakis(2-(1-ethylbenzimidazolyl))-2-hydroxy-1,3-diaminopropane), a similar, straightforward process could not be used for the synthesis of diiron(II) complexes with free thiol groups. In order to circumvent this problem, a new class of thiolate bridged diiron(II) complexes, [Fe2(N-Et-HPTB)(μ-SR¹)](BF4)2 (R¹ = Me (1a), Et (1b), tBu (1c), Ph (1d)) was synthesized. Selective proton exchange reactions of one representative compound, 1b, with reagents of the type HS-R²-COOH yielded the target compounds, [Fe2(N-Et-HPTB)(μ-O2C-R²-SH)](BF4)2 (R² = C6H4 (3a), CH2CH2 (3b), CH2(CH2)5CH2 (3c)). Redox properties of the complexes 3a-3c were studied in comparison with the complex, [Fe2(N-Et-HPTB)(μ-O2CMe)](BF4)2 (5). Reaction of (Cp2Fe)(BF4) with 1b yielded [FeII2(N-Et-HPTB)(DMF)3](BF4)3DMF (4) (when crystallized from DMF/diethyl ether), which might indicate the formation of a transient ethanethiolate bridged {FeIIFeIII} species, followed by a rapid internal redox reaction to generate diethyldisulfide and the solvent coordinated diiron(II) complex, 4. This possibility was supported by a comparative cyclic voltammetric study of 1a-1c and 4. Prospects of the complexes of the type 3a-3c as potential building blocks for the synthesis of nonheme diiron(II) complexes covalently attached with other redox active metals has been substantiated by the synthesis of the complexes, [Fe2(N-EtHPTB)(μ-O2C-R²-S)Cu(Me3TACN)](BF4)2 (R = p-C6H4 (7a), CH2CH2 (7b)). All the compounds were characterized by a combination of single-crystal X-ray structure determinations and/or elemental analysis. [ABSTRACT FROM AUTHOR]