The reactivity of six Mn-IV-oxo complexes in C-H bond oxidation has been examined using a combination of kinetic experiments and computational methods. Variable-temperature studies of the oxidation of 9,10-dihydroanthracene (DHA) and ethylbenzene by these Mn-IV-oxo complexes yielded activation parameters suitable for evaluating electronic structure computations. Complementary kinetic experiments of the oxidation of deuterated DHA provided evidence for hydrogen-atom tunneling in C-H bond oxidation for all Mn-IV-oxo complexes. These results are in accordance with the Bell model, where tunneling occurs near the top of the transition-state barrier. Density functional theory (DFT) and DLPNO-CCSD(T-1) computations were performed for three of the six Mn-IV-oxo complexes to probe a previously predicted multistate reactivity model. The DFT computations predicted a thermal crossing from the B-4(1) ground state to a E-4 state along the C-H bond oxidation reaction coordinate. DLPNO-CCSD(T-1) calculations further confirm that the E-4 transition state offers a lower energy barrier, reinforcing the multistate reactivity model for these complexes. We discuss how this multistate model can be reconciled with recent computations that revealed that the kinetics of C-H bond oxidation by this set of Mn-IV-oxo complexes can be well-predicted on the basis of the thermodynamic driving force for these reactions.

Four new pentadentate N5-donor ligands, [N-(1-methyl-2-imidazolyl)methyl-N-(2-pyridyl)-methyl-N-(bis-2-pyridylmethyl)-amine] (L1), [N-bis(1-methyl-2-imidazolyl)methyl-N-(bis-2-pyridylmethyl)amine] (L2), (N-(isoquinolin-3-ylmethyl)-1,1-di(pyridin-2-yl)-N-(pyridin-2-ylmethyl)methanamine (L3), and N,N-bis(isoquinolin-3-ylmethyl)-1,1-di(pyridin-2-yl)methanamine (L4), have been synthesized based on the N4Py ligand framework, where one or two pyridyl arms of the N4Py parent are replaced by (N-methyl)imidazolyl or N-(isoquinolin-3-ylmethyl) moieties. Using these four pentadentate ligands, the mononuclear complexes [FeII(CH3CN)(L1)]2+ (1a), [FeII(CH3CN)(L2)]2+ (2a), [FeII(CH3CN)(L3)]2+ (3a), and [FeII(CH3CN)(L4)]2+ (4a) have been synthesized and characterized. The half-wave potentials (E1/2) of the complexes become more positive in the order: 2a < 1a < 4a ≤ 3a ≤ [Fe(N4Py)(CH3CN)]2+. The order of redox potentials correlates well with the Fe-Namine distances observed by crystallography, which are 2a > 1a ≥ 4a > 3a ≥ [Fe(N4Py)(CH3CN)]2+. The corresponding ferryl complexes [FeIV(O)(L1)]2+ (1b), [FeIV(O)(L2)]2+ (2b), [FeIV(O)(L3)]2+ (3b), and [FeIV(O)(L4)]2+ (4b) were prepared by the reaction of the ferrous complexes with isopropyl 2-iodoxybenzoate (IBX ester) in acetonitrile. The greenish complexes 3b and 4b were also isolated in the solid state by the reaction of the ferrous complexes in CH3CN with ceric ammonium nitrate in water. Mössbauer spectroscopy and magnetic measurements (using superconducting quantum interference device) show that the four complexes 1b, 2b, 3b, and 4b are low-spin (S = 1) FeIV═O complexes. UV/vis spectra of the four FeIV═O complexes in acetonitrile show typical long-wavelength absorptions of around 700 nm, which are expected for FeIV═O complexes with N4Py-type ligands. The wavelengths of these absorptions decrease in the following order: 721 nm (2b) > 706 nm (1b) > 696 nm (4b) > 695 nm (3b) = 695 nm ([FeIV(O) (N4Py)]2+), indicating that the replacement of the pyridyl arms with (N-methyl) imidazolyl moieties makes L1 and L2 exert weaker ligand fields than the parent N4Py ligand, while the ligand field strengths of L3 and L4 are similar to the N4Py parent despite the replacement of the pyridyl arms with N-(isoquinolin-3-ylmethyl) moieties. Consequently, complexes 1b and 2b tend to be less stable than the parent [FeIV(O)(N4Py)]2+ complex: the half-life sequence at room temperature is 1.67 h (2b) < 16 h (1b) < 45 h (4b) < 63 h (3b) ≈ 60 h ([FeIV(O)(N4Py)]2+). Compared to the parent complex, 1b and 2b exhibit enhanced reactivity in both the oxidation of thioanisole in the oxygen atom transfer (OAT) reaction and the oxygenation of C-H bonds of aromatic and aliphatic substrates, presumed to occur via an oxygen rebound process. Furthermore, the second-order rate constants for hydrogen atom transfer (HAT) reactions affected by the ferryl complexes can be directly related to the C-H bond dissociation energies of a range of substrates that have been studied. Using either IBX ester or H2O2 as an oxidant, all four new FeII complexes display good performance in catalytic reactions involving both HAT and OAT reactions.

A series of manganese(II) and oxomanganese(IV) complexes supported by neutral, pentadentate ligands with varied equatorial ligand-field strength (N3pyQ, N2py2I, and N4pyMe2) were synthesized and then characterized using structural and spectroscopic methods. On the basis of electronic absorption spectroscopy, the [MnIV(O)(N4pyMe2)]2+ complex has the weakest equatorial ligand field among a set of similar MnIV-oxo species. In contrast, [MnIV(O)(N2py2I)]2+ shows the strongest equatorial ligand-field strength for this same series. We examined the influence of these changes in electronic structure on the reactivity of the oxomanganese(IV) complexes using hydrocarbons and thioanisole as substrates. The [MnIV(O)(N3pyQ)]2+ complex, which contains one quinoline and three pyridine donors in the equatorial plane, ranks among the fastest MnIV-oxo complexes in C-H bond and thioanisole oxidation. While a weak equatorial ligand field has been associated with high reactivity, the [MnIV(O)(N4pyMe2)]2+ complex is only a modest oxidant. Buried volume plots suggest that steric factors dampen the reactivity of this complex. Trends in reactivity were examined using density functional theory (DFT)-computed bond dissociation free energies (BDFEs) of the MnIIIO-H and MnIV ═ O bonds. We observe an excellent correlation between MnIV═O BDFEs and rates of thioanisole oxidation, but more scatter is observed between hydrocarbon oxidation rates and the MnIIIO-H BDFEs.

Purpose The purpose of this study is to empirically explore the connection between transformational leadership (TL) and organizational effectiveness (OE). Also, the paper looks at the mediating impact of employee innovative behaviour (EIB) and the moderating effect of knowledge sharing (KS) on the aforementioned association. Design/methodology/approach The respondents included 410 bank employees from North India. The mediating effect of EIB and moderating effect of KS was explored by plug-in for SPSS, PROCESS Macro (Hayes). Findings The investigation demonstrated that there exists a significant relationship between the constructs under examination. Further, it was seen that EIB mediated and KS moderated the connection between TL and OE. Practical implications Looking at the associations among TL, KS, EIB and OE can have significant implications for organizations. The considered framework as proposed can be used to outline organizational practices, to frame organizational policies and to build a pool of innovative employees who will in turn enhance OE. Originality/value The general comprehension of the associations among TL, KS, EIB and OE is insufficient in existing literature. This examination expands on past studies by examining the mediating role of the EIB and moderating role of KS between TL and OE. The present work is one of the rare attempts to investigate this nested association in the Indian context.

The isolation, characterization, and dioxygen reactivity of monomeric [(TPA)MII(mandelate)]+ (M = Fe, 1; Co, 3) and dimeric [(BPMEN)2MII2(μ-mandelate)2]2+ (M = Fe, 2; Co, 4) (TPA = tris(2-pyridylmethyl)amine and BPMEN = N1,N2-dimethyl-N1,N2-bis(pyridin-2-yl-methyl)ethane-1,2-diamine) complexes are reported. The iron(II)- and cobalt(II)-mandelate complexes react with dioxygen to afford benzaldehyde and benzoic acid in a 1:1 ratio. In the reactions, one oxygen atom from dioxygen is incorporated into benzoic acid, but benzaldehyde does not derive any oxygen atom from dioxygen. While no O2-derived intermediate is observed with the iron(II)-mandelate complexes, the analogous cobalt(II) complexes react with dioxygen at a low temperature (-80 °C) to generate the corresponding cobalt(III)-superoxo species (S), a key intermediate implicated in the initiation of mandelate decarboxylation. At -20 °C, the cobalt(II)-mandelate complexes bind dioxygen reversibly leading to the formation of μ-1,2-peroxo-dicobalt(III)-mandelate species (P). The geometric and electronic structures of the O2-derived intermediates (S and P) have been established by computational studies. The intermediates S and P upon treatment with a protic acid undergo decarboxylation to afford benzaldehyde (50%) with a concomitant formation of the corresponding μ-1,2-peroxo-μ-mandelate-dicobalt(III) (P1) species. The crystal structure of a peroxide species isolated from the cobalt(II)-carboxylate complex [(TPA)CoII(MPA)]+ (5) (MPA = 2-methoxyphenylacetate) supports the composition of P1. The observations of the dioxygen-derived intermediates from cobalt complexes and their electronic structure analyses not only provide information about the nature of active species involved in the decarboxylation of mandelate but also shed light on the mechanistic pathway of two-electron versus four-electron reduction of dioxygen.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

A series of iron(II) complexes with the general formula [FeII(L2-Qn)(L)]n+ (n = 1, L = F-, Cl-; n = 2, L = NCMe, H2O) have been isolated and characterized. The X-ray crystallographic data reveals that metal-ligand bond distances vary with varying ligand field strengths of the sixth ligand. While the complexes with fluoride, chloride and water as axial ligand are high spin, the acetonitrile-coordinated complex is in a mixed spin state. The steric bulk of the quinoline moieties forces the axial ligands to deviate from the Fe-Naxial axis. A higher deviation/tilt is noted for the high spin complexes, while the acetonitrile coordinated complex displays least deviation. This deviation from linearity is slightly less in the analogous low-spin iron(II) complex [FeII(L1-Qn)(NCMe)]2+ of the related asymmetric ligand L1-Qn due to the presence of only one sterically demanding quinoline moiety. The two iron(II)-acetonitrile complexes [FeII(L2-Qn)(NCMe)]2+ and [FeII(L1-Qn)(NCMe)]2+ generate the corresponding iron(IV)-oxo species with higher thermal stability of the species supported by the L1-Qn ligand. The crystallographic and spectroscopic data for [FeIV(O)(L1-Qn)](ClO4)2 bear resemblance to other crystallographically characterized S = 1 iron(IV)-oxo complexes. The hydrogen atom transfer (HAT) and oxygen atom transfer (OAT) reactivities of both the iron(IV)-oxo complexes were investigated, and a Box-Behnken multivariate optimization of the parameters for catalytic oxidation of cyclohexane by [FeII(L2-Qn)(NCMe)]2+ using hydrogen peroxide as the terminal oxidant is presented. An increase in the average Fe-N bond length in [FeII(L1-Qn)(NCMe)]2+ is also manifested in higher HAT and OAT rates relative to the other reported complexes of ligands based on the N4Py framework. The results reported here confirm that the steric influence of the ligand environment is of critical importance for the reactivity of iron(IV)-oxo complexes, but additional electronic factors must influence the reactivity of iron-oxo complexes of N4Py derivatives.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Background: Excessive application of nitrogen (N) fertilizer in cereal crops not only decreases the N use efficiency but also accelerates greenhouse gas (GHG) emission. Aim: To improve N use efficiency in wheat (Triticum aestivum L.) using precision N management and coating seeds with arbuscular mycorrhizal fungi (AMF). Methods: Field experiment laid out in split-plot design was conducted to study the role of AMF consortia (four species) seed coating and different precision N management strategies in rationalizing fertilizer N use. Results: The AMF seed coating improved mycorrhization but did not improve N assimilation, grain yield, root weight, N uptake, chlorophyll value, normalized difference vegetative index, and physiological efficiency (PEN) of applied N fertilizer. The benefits of AMF seed coating in improving N assimilation were not visible even in no-N treatment. Precision N management using leaf color chart (LCC), chlorophyll meter (SPAD), and GreenSeeker optical sensor (GS) sustained wheat grain yield equivalent to the soil-test based N fertilizer recommendation with the average savings of 20% N fertilizer. Precision N management strategies improved mean recovery efficiency (REN) and partial factor productivity (PFPN) of applied N fertilizer, respectively by 26.0% and 26.4% over the soil-test based N management. Spectral properties measured with LCC, SPAD and GS showed good correlation (R-2 > 0.71) with grain yield, depicting great potential of optical sensing tools in predicting grain yield and inferring need-based fertilizer N topdressings decisions in wheat. Conclusions: Precision N management provides a potential solution to improve N nutrition in wheat while reducing nitrous oxide (N2O) and total GHG emissions by 23.2 and 23.6%, respectively, in comparison to soil-test based N application.

Identification of polychaetes from the Vellar estuary mangroves is very essential to assess their diversity status. In this study, we have used sequences of the Cytochrome Oxidase I (COI) from 15 species belongs to eight families to barcode and investigate the molecular variation among the Vellar estuary polychaetes. Based on the sequence data, it was observed that the maximum A+T content (62.00%) was recorded in Diopatra neapolitana and minimum (55.00%) in Laonice cirrata. Similarly, the maximum C+G value of 45.00% was observed in Laonice cirrata and least content of 38.00% was estimated in Capitella capitata and Diopatra neapolitana. The maximum K2P distance (1.459) was found between Lubrineridae and Capitellidae family. Whereas, the minimum K2P distance of 0.270 was observed between Nereididae and Spionidae. However, the maximum K2P distance within family was observed in Lubrineridae (0.197) and the minimum value of 0.005 was recorded in Spionidae.The maximum K2P distance (1.459) was found between the genus Capitella and Lumbrineris whereas the minimum distance (0.230) was observed between Platynereis and Perinereis. However, the maximum K2P distance within genus was observed in Perinereis (0.211) whereas the minimum distance of 0.005 was perceived in Laonice. The intra genus K2P genetic distance in Marphysa, Naineris, Platynereis, Capitella, Diopatra was zero. The maximum likelihood tree clearly demonstrates the efficacy of COI gene in discriminating polychaete individuals both at conspecific and congeneric levels. Further molecular tools such as microsattelite, RAPD is needed to assess the population structure of the above identified species.

AIM:To investigate the genetic and pathogenic variability of Xanthomonas oryzae pv. oryzae causing bacterial blight in rice on the remote Andaman Islands, India.METHODS AND RESULTS:A total of 27 yellow-pigmented bacterial isolates representing rice fields of Andaman Islands incited blight on the susceptible-rice cultivar, C14-8. Phenotypic, pathogenic traits and 16S rRNA gene sequences revealed their identity as X. oryzae pv. oryzae. Virulence profiling indicated the prevalence of seven pathotypes of X. oryzae pv. oryzae on the Islands. Pathotypes-VI and -VII were highly virulent, whereas the pathotype-I was less virulent. Multilocus sequence typing based on nucleotide sequence polymorphism in nine housekeeping genes dnaK; fyuA; gyrB (two loci): rpoD; fusA; gapA; gltA and lepA clustered 27 isolates into 17 sequence types (STs) segregated into two clonal-complexes (CC). While CC-I comprised of isolates from Andaman Island, the CC-II is a mixture of isolates representing mainland India and Andaman Island. The data revealed trans-boundary pathogen introduction and a consequent intra-regional diversification on these islands due to the deployment of different rice cultivars in different regions.CONCLUSIONS:Genotyping and pathotyping of sland isolates revealed seven pathotypes distributed in two clonal complexes with strong indications for trans-boundary movement and consequent diversification of the bacterial pathogen. Highly virulent pathotypes of X. oryzae pv. oryzae that could overcome combinations of R-genes, xa13+Xa21 as well as xa5+xa13 were found prevalent in the Andaman Islands SIGNIFICANCE AND IMPACT OF THE STUDY: Genetic and virulence analysis of X. oryzae pv. oryzae in the Andaman Islands revealed introduction and host-mediated regional diversification and local adaptation of X oryzae pv. oryzae. The study calls for the need of multi-gene pyramiding for durable disease resistance and establishing stringent quarantine measures for safeguarding island agricultural practices in the future.

The purpose of this article is to conceptualize, develop and validate a scale for measuring organizational effectiveness (OE). The methodology comprises of the extant literature review of studies conducted on scale construction of OE. In the exploratory phase, 11 baseline dimensions of OE were established which was followed by the qualitative study in order to determine the items contributing to these factors. The confirmatory factor analysis (CFA) was used to validate the scale by using the data generated from 353 bank employees. Additionally, OE has been specified as a second-order factor, measured by its 11 first-order factors. CFA model fit indicators for the proposed scale were found good according to the recommended values. The scale exhibited inclusive psychometric properties as per the results from the varied reliability and validity checks. Also, the second-order measurement model suggested OE to be most affected by 'organization innovation'. Factors considered for OE while designing the research instrument are the guidelines for the management which cater the organization at the individual level.

A 5-year field study was conducted to improve nitrogen (N) and phosphorus (P) use efficiencies in wheat with the synergistic use of plant growth-promoting rhizobacteria (PGPR), arbuscular mycorrhizal fungi (AMF), and spectral properties for deriving need-based fertilizer N management decisions. Bio-fertilizer consortium inoculation on wheat seed improved rhizosphere mycorrhization, albeit native mycorrhiza also produced mycorrhiza colonization. Lower mycorrhiza colonization was observed in no-P and high P treatments at 30 and 60 days after sowing (DAS) when wheat seeds were not inoculated with bio-fertilizer. However, the mycorrhiza colonization was independent of the fertilizer P level at 60 DAS in the inoculated treatments. The integrated nutrient management with bio-fertilizer and need-based N use sustained highest grain yield with 16.7% and 25% less use of fertilizer N and P, respectively. The agronomic (AE) and recovery efficiencies (RE) of applied N and P were increased by 23.0% (AE(N)), 21.3% (REN), 40.2% (AE(P)) and 49.8% (REP), respectively. On-farm validation studies exhibited improvement in partial factor productivity of fertilizer P (PFPP) by 35.8% and fertilizer N (PFPN) by 22.5% in comparison with the soil test-based recommendation. The synergistic use of bio-fertilizer and need-based N management improved the PGPR population, dehydrogenase and alkaline phosphatase activities in soil. The improved soil microbiological properties attributed to better mycorrhization and microflora propagation in soil-facilitated nutrient assimilation and thus higher N and P use efficiencies in wheat.

Application of fertilizer nitrogen (N) and phosphorus (P) in excess of crop requirement causes nutritional imbalances in soil along with economic and ecological losses. The optical sensors (leaf color chart, chlorophyll meter, and GreenSeeker) help guide real-time N topdressing decisions and arbuscular mycorrhizal fungi (AMF) further improve nutrient uptake from soil. A four-year field study was conducted to improve N- and P-use efficiencies in maize using different optical sensing tools and coating seeds with AMF. The AMF seed coating improved mycorrhizal colonization in soil. Higher mycorrhization was observed in no-P treatment; however, P fertilization and mycorrhiza inoculation diminish the effect as growth progressed from 30 to 60 days after sowing. The mycorrhizal inoculation increased grain yield by 17.1% in no-N treatment; however, the response diminishes with N fertilization. The optical sensing–based N management sustained grain yield, total N uptake, and root and plant dry weight equivalent to the soil test–based fertilizer N recommendation with the less use of 30 kg N ha−1. The respective improvement in agronomic and recovery efficiencies of applied fertilizer N up to 38.6 and 34.9% highlights the potential of optical sensing tools and the inability of soil test–based N recommendation for precision N management. Mitigated greenhouse and nitrous oxide emissions respectively by 30.7% and 29.7% further underline the prominence of replacing soil test N recommendations with optical sensing–guided N top-dressings. Sufficient inherent soil P restricts the AMF benefits in improving P-use efficiencies in maize.

Three new iron(II)-benzilate complexes [(N4Py)Fe-II(benzilate)]ClO4 (1), [(N4Py(Me2))Fe-II(benzilate)]ClO4 (2) and [(N4Py(Me4))Fe-II(benzilate)]ClO4 (3) of neutral pentadentate nitrogen donor ligands have been isolated and characterized to study their dioxygen reactivity. Single-crystal X-ray structures reveal a mononuclear six-coordinate iron(II) center in each case, where benzilate binds to the iron center in monodentate mode via one carboxylate oxygen. Introduction of methyl groups in the 6-positions of the pyridine rings makes the N4Py(Me2) and N4Py(Me4) ligand fields weaker compared to that of the parent N4Py ligand. All the complexes (1-3) react with dioxygen to decarboxylate the coordinated benzilate to benzophenone quantitatively. The decarboxylation is faster for the complex of the more sterically hindered ligand and follows the order 3>2>1. The complexes display oxygen atom transfer reactivity to thioanisole and also exhibit hydrogen atom transfer reactions with substrates containing weak C-H bonds. Based on interception studies with external substrates, labelling experiments and Hammett analysis, a nucleophilic iron(II)-hydroperoxo species is proposed to form upon two-electron reductive activation of dioxygen by each iron(II)-benzilate complex. The nucleophilic oxidants are converted to the corresponding electrophilic iron(IV)-oxo oxidant upon treatment with a protic acid. The high-spin iron(II)-benzilate complex with the weakest ligand field results in the formation of a more reactive iron-oxygen oxidant.

Copper coordination complexes have emerged as a group of transition metal complexes that play important roles in solar energy conversion, utilization and storage, and have the potential to replace the quintessential commonly used transition metals, like Co, Pt, Ir and Ru as light sensitizers, redox mediators, electron donors and catalytic centers. The applications of copper coordination compounds in chemistry and energy related technologies are many and demonstrate their rightful place as sustainable, low toxicity and Earth-abundant alternative materials. In this perspective we show the most recent impact made by copper coordination complexes in dye-sensitized solar cells and other energy relevant applications.

The oxomanganese(IV) complex [(dpaq)MnIV(O)]+-Mn+ (1-Mn+, Mn+ = redox-inactive metal ion, H-dpaq = 2-[bis(pyridin-2-ylmethyl)]amino-N-quinolin-8-ylacetamide), generated in the reaction of the precursor hydroxomanganese(III) complex 1 with iodosylbenzene (PhIO) in the presence of redox-inactive metal triflates, has recently been reported. Herein the generation of the same oxomanganese(IV) species from 1 using various combinations of protic acids and oxidants at 293 K is reported. The reaction of 1 with triflic acid and the one-electron-oxidizing agent [RuIII(bpy)3]3+ leads to the formation of the oxomanganese(IV) complex. The putative species has been identified as a mononuclear high-spin (S = 3/2) nonheme oxomanganese(IV) complex (1-O) on the basis of mass spectrometry, Raman spectroscopy, EPR spectroscopy, and DFT studies. The optical absorption spectrum is well reproduced by theoretical calculations on an S = 3/2 ground spin state of the complex. Isotope labeling studies confirm that the oxygen atom in the oxomanganese(IV) complex originates from the MnIII-OH precursor and not from water. A mechanistic investigation reveals an initial protonation step forming the MnIII-OH2 complex, which then undergoes one-electron oxidation and subsequent deprotonations to form the oxomanganese(IV) transient, avoiding the requirements of either oxo-transfer agents or redox-inactive metal ions. The MnIV-oxo complex cleaves the C-H bonds of xanthene (k2 = 5.5 M-1 s-1), 9,10-DHA (k2 = 3.9 M-1 s-1), 1,4-CHD (k2 = 0.25 M-1 s-1), and fluorene (k2 = 0.11 M-1 s-1) at 293 K. The electrophilic character of the nonheme MnIV-oxo complex is demonstrated by a large negative ρ value of 2.5 in the oxidation of para-substituted thioanisoles. The complex emerges as the "most reactive" among the existing MnIV/V-oxo complexes bearing anionic ligands.

Analysis of extended X-ray absorption fine structure (EXAFS) data for the Mn-IV-oxo complexes [Mn-IV(O)((DMM)N4py)](2+), [Mn-IV(O)(2pyN2B)](2+), and [Mn-IV(O)(2pyN2Q)](2+) ((DMM)N4py=N,N-bis(4-methoxy-3,5-dimethyl-2-pyridylmethyl)-N-bis(2-pyridyl)methylamine; 2pyN2B=(N-bis(1-methyl-2-benzimidazolyl)methyl-N-(bis-2-pyridylmethyl)amine, and 2pyN2Q=N,N-bis(2-pyridyl)-N,N-bis(2-quinolylmethyl)methanamine) afforded Mn=O and Mn-N bond lengths. The Mn=O distances for [Mn-IV(O)((DMM)N4py)](2+) and [Mn-IV(O)(2pyN2B)](2+) are 1.72 and 1.70 angstrom, respectively. In contrast, the Mn=O distance for [Mn-IV(O)(2pyN2Q)](2+) was significantly longer (1.76 angstrom). We attribute this long distance to sample heterogeneity, which is reasonable given the reduced stability of [Mn-IV(O)(2pyN2Q)](2+). The Mn=O distances for [Mn-IV(O)((DMM)N4py)](2+) and [Mn-IV(O)(2pyN2B)](2+) could only be well-reproduced using DFT-derived models that included strong hydrogen-bonds between second-sphere solvent 2,2,2-trifluoroethanol molecules and the oxo ligand. These results suggest an important role for the 2,2,2-trifluoroethanol solvent in stabilizing Mn-IV-oxo adducts. The DFT methods were extended to investigate the structure of the putative [Mn-IV(O)(N4py)](2+).(HOTf)(2) adduct. These computations suggest that a Mn-IV-hydroxo species is most consistent with the available experimental data.

Using the pentadentate ligand (N-bis(1-methyl-2-benzimidazolyl)methyl-N-(bis-2-pyridylmethyl)amine, 2pyN2B), presenting two pyridyl and two (N-methyl)benzimidazolyl donor moieties in addition to a central tertiary amine, new MnII and MnIV-oxo complexes were generated and characterized. The [MnIV(O)(2pyN2B)]2+ complex showed spectroscopic signatures (i.e., electronic absorption band maxima and intensities, EPR signals, and Mn K-edge X-ray absorption edge and near-edge data) similar to those observed for other MnIV-oxo complexes with neutral, pentadentate N5 supporting ligands. The near-IR electronic absorption band maximum of [MnIV(O)(2pyN2B)]2+, as well as DFT-computed metric parameters, are consistent with the equatorial (N-methyl)benzimidazolyl ligands being stronger donors to the MnIV center than the pyridyl and quinolinyl ligands found in analogous MnIV-oxo complexes. The hydrogen- and oxygen-atom transfer reactivities of [MnIV(O)(2pyN2B)]2+ were assessed through reactions with hydrocarbons and thioanisole, respectively. When compared with related MnIV-oxo adducts, [MnIV(O)(2pyN2B)]2+ showed muted reactivity in hydrogen-atom transfer reactions with hydrocarbons. This result stands in contrast to observations for the analogous FeIV-oxo complexes, where [FeIV(O)(2pyN2B)]2+ was found to be one of the more reactive members of its class.