Product Complex Research Articles

Quantitative dynamics of paradigmatic SN2 reaction OH- + CH3F on accurate full-dimensional potential energy surface.

The bimolecular reaction between OH- and CH3F is not just a prototypical SN2 process, but it has three other product channels. Here, we develop an accurate full-dimensional potential energy surface (PES) based on 191 193 points calculated at the level CCSD(T)-F12a/aug-cc-pVTZ. A detailed dynamics and mechanism analysis was carried out on this potential energy surface using the quasi-classical trajectory approach. It is verified that the trajectories do not follow the minimum energy path (MEP), but directly dissociate to F- and CH3OH. In addition, a new transition state for proton exchange and a new product complex CH2F-⋯H2O for proton abstraction were discovered. The trajectories avoid the transition state or this complex, instead dissociate to H2O and CH2F- directly through the ridge regions of the minimum energy path before the transition state. These non-MEP dynamics become more pronounced at high collision energies. Detailed dynamic simulations provide new insights into the atomic-level mechanisms of the title reaction, thanks to the new chemically accurate PES, with the aid of machine learning.

Theoretical study of H-abstraction and addition reactions of cyclohexene with H, OH and HO2

Reactions with small radicals are of essential significance for alkene oxidation. In this work, the potential energy surfaces and rate constants of cyclohexene plus H, OH, HO2 radicals were thoroughly investigated. The molecular geometries and vibrational frequencies were calculated for all stationary points at BHandHLYP/6-311++G(d,p) level, and then the single point energies were refined at DLPNO-CCSD(T)/CBS level. It contained secondary alkyl, allylic, vinyl H-abstraction and addition channels. The axial and equatorial carbon sites were calculated separately. The reactant and product complexes for allylic H-abstraction and addition channels by OH and HO2 were located with lower energies than the path entrance or exit. In contrast, those complexes for pathways with H-atom had higher energies than reactants or products. The barrierless formation process of reactant complex for cyclohexene plus OH/HO2 was consider to evaluate the influences on rate constants. Rate constants were determined using canonical variational transition state theory in consideration of quantum transmission effects. Notable tunneling effects are observed for H-abstraction reactions with H and HO2 radicals, of which low-temperature rate constants are enhanced, whereas variational and recrossing coefficients of channels with OH deviate far from unity, rendering lower rate constants than those obtained at conventional transition state theory. Comparison of rate constants with similar reactions published in literatures showed that fairly agreements were achieved for H-abstraction and addition channels with H and HO2, but great gaps are noted for those with OH radical. Branching ratio analysis exhibited that addition reactions dominated at T < 1000 K and allylic H-abstraction reactions turned more significant as temperature increased.

Research on the Development of GuangXi Agricultural Product Logistics under the Background of Rural Revitalization

As a large agricultural country, ensuring the steady development of agriculture is the most important task concerning the national economy and people's livelihood. In the context of rural revitalization, achieving rural prosperity is the primary goal. Agricultural product logistics not only affects the development of rural economy, but also plays a vital role in the development of agriculture. Therefore, this paper takes Guangxi as an example, studies and analyzes the current situation of agricultural product logistics under the background of rural revitalization, puts forward problems such as backward agricultural product logistics infrastructure and complex circulation links, and puts forward corresponding countermeasures and suggestions to strengthen infrastructure construction and reduce circulation links. It is of great significance to improve the logistics development of agricultural products in Guangxi and promote the local economic development.

Monitoring and investigating reactive extraction of (di–)carboxylic acids using online FTIR – Part II: Reaction equilibria, reaction kinetics and competition within the complex formation between itaconic acid and several amine extractants

The downstream processing of biocatalytically produced (di–)carboxylic acids still is a challenging task. One innovative approach, demonstrating industrial applicability, applies an initial reactive extraction (RE) using hydrophobic amine extractants into an organic solvent, followed by a subsequent back-extraction (BE) using water soluble amine extractants into a (fresh) aqueous solution. Although showing promising results in terms of yield and selectivity, state-of-the-art amine extractant selection is only based on trial-and-error screening approaches. Thus, to enable an optimized process design and thereby optimized downstream processing, a deeper understanding of RE and BE on a molecular level is crucial.Within this work, we successfully applied an experimental setup incorporating online Fourier Transform Infrared (FTIR) spectroscopy to elucidate influencing factors on RE and BE as well as to provide a guideline for an optimized selection of amine extractants. Investigations on the kinetics of complex formation between itaconic acid (IA) and tri-n-octylamine (TNOA) in 1-decanol revealed the reaction order to be zero in TNOA, indicating that mass transfer is the rate limiting step in RE. Reaction equilibrium investigations revealed that for all IA - amine extractants combinations in 1-decanol reaction equilibrium was almost completely on the product (complex) side. The strength of the acid-extractant complexes was evaluated using FTIR experiments, providing a novel approach / methodology to efficiently select an optimal combination of amine extractants for RE and BE. Applying the novel online FTIR spectroscopy setup allowed to monitor a complete process sequence of RE and BE of IA with selected amine extractants, validating the proposed guidelines for an optimized selection of amine extractants. The results of this work will facilitate the definition of appropriate RE and BE systems for biocatalytically produced (di–)carboxylic acids.

Purification and characterization of protease M, a yeast mitochondrial nucleotide-stimulated metal protease: its identification as CYM1 gene product, a mitochondrial presequence peptidase.

A chelator-sensitive protease in the mitochondrial matrix of the yeast, Saccharomyces cerevisiae (Biochem. Biophys. Res. Commun. 144, 277, 1987), was purified and characterized. The purified enzyme, termed protease M, specifically hydrolyzes peptide substrates on the N-side of the paired basic residues. When mastoparan was used as substrate, it cleaved Ala8-Leu9 and Lys11-Lys12 bonds as well as the N-side of Lys11-Lys12 residues. Nucleotide triphosphates stimulated the activity 3-fold at 2.5mM. The genomic DNA sequence showed that protease M was a gene product of CYM1 known as mitochondrial presequence protease homologue in S. cerevisiae, encoding a 989-amino acid-long precursor protein. The N-terminal sequence of the purified enzyme indicated that protease M has 16-residue signal sequence and the 'mature' protein consists of 973 amino acids with a molecular mass of 110kDa. Protease M contained consensus sequence motifs of ATP-binding site very near the carboxyl terminus. The alignment of the two ATP-binding motifs is an inverted version of the common alignment. Gene disruption of the enzyme generates mixed subunits in tetrameric MnSOD formed with 23-kDa mature and 24-kDa partial presequence-containing subunits. This report describes newly identified enzyme properties of the CYM1 gene product, protease M and abnormal MnSOD complex formation of the disruption mutant.

Potential Therapeutic Mechanism of Traditional Chinese Medicine on Diabetes in Rodents: A Review from an NMR-Based Metabolomics Perspective

Traditional Chinese medicine (TCM) has been used to treat diabetes for a long time, but its application has not been widely accepted due to unstandardized product quality and complex pharmacological mechanisms. The modernization of TCM is crucial for its further development, and in recent years the metabolomics technique has largely driven its modernization. This review focuses on the application of NMR-based metabolomics in diabetic therapy using TCM. We identified a series of metabolic pathways that altered significantly after TCM treatment, providing a better understanding of the metabolic mechanisms of TCM for diabetes care.

C-H and Si-H Activation Reactions at Ru/Ga Complexes: A Combined Experimental and Theoretical Case Study on the Ru-Ga Bond.

Treatment of [Ru(COD)(MeAllyl)2 ] and [Ru(COD)(COT)] with GaCp* under hydrogenolytic conditions leads to reactive intermediates which activate Si-H or C-H bonds, respectively. The product complexes [Ru(GaCp*)3 (SiEt3 )H3 ] (1) and [Ru(GaCp*)3 (C7 H7 )H3 ] (2) are formed with HSiEt3 or with toluene as the solvent, respectively. While 1 was isolated and fully characterized by NMR, MS, IR and SC-XRD, 2 was too labile to be isolated and was observed and characterized in situ by using mass spectrometry, including labelling experiments for the unambiguous assignment of the elemental composition. The structural assignment was confirmed by DFT calculations. The relative energies of the four isomers possible upon toluene activation at the ortho-, meta-, para- and CH3 -positions have been determined and point to aromatic C-H activation. The Ru-Ga bond was analyzed by EDA and QTAIM and compared to the Ru-P bond in the analogue phosphine compound. Bonding analyses indicate that the Ru-GaCp* bond is weaker than the Ru-PR3 bond.

Pre-steady-state kinetic and mutational insights into mechanisms of endo- and exonuclease DNA processing by mutant forms of human AP endonuclease

Human apurinic/apyrimidinic endonuclease APE1 catalyzes endonucleolytic hydrolysis of phosphodiester bonds on the 5′ side of structurally unrelated damaged nucleotides in DNA or native nucleotides in RNA. APE1 additionally possesses 3′-5′-exonuclease, 3′-phosphodiesterase, and 3′-phosphatase activities. According to structural data, endo- and exonucleolytic cleavage of DNA is executed in different complexes when the excised residue is everted from the duplex or placed within the intrahelical DNA cavity without nucleotide flipping. In this study, we investigated the functions of residues Arg177, Arg181, Tyr171 and His309 in the APE1 endo- and exonucleolytic reactions. The interaction between residues Arg177 and Met270, which was hypothesized recently to be a switch for endo- and exonucleolytic catalytic mode regulation, was verified by pre–steady-state kinetic analysis of the R177A APE1 mutant. The function of another DNA-binding–site residue, Arg181, was analyzed too; it changed its conformation when enzyme–substrate and enzyme–product complexes were compared. Mutation R181A significantly facilitated the product dissociation stage and only weakly affected DNA-binding affinity. Moreover, R181A reduced the catalytic rate constant severalfold due to a loss of contact with a phosphate group. Finally, the protonation/deprotonation state of residues Tyr171 and His309 in the catalytic reaction was verified by their substitution. Mutations Y171F and H309A inhibited the chemical step of the AP endonucleolytic reaction by several orders of magnitude with retention of capacity for (2R,3S)-2-(hydroxymethyl)-3-hydroxytetrahydrofuran-containing-DNA binding and without changes in the pH dependence profile of AP endonuclease activity, indicating that deprotonation of these residues is likely not important for the catalytic reaction.

Mannich metal complex: Synthesis, reaction mechanism and computational studies

Metal mediated Mannich aminomethylation reaction involving metal(II)glycinato complex, formaldehyde, and ethyl acetoacetate (EAA) was carried out under mild aqueous conditions. Under the optimized condition, the reaction yielded only a single Mannich base product in a moderate yield without any contamination with the aldol condensation by-product. The Mannich base product obtained was characterized and confirmed by elemental analysis, UV–Vis spectroscopy, IR, ESI-MS, ESR, and GCMS–. The structure of the Mannich base product was investigated by Density Functional Theory (DFT). The structure interpretation of the product from the DFT data supported the proposed structure and was found to have an N2O2 four coordination square planar geometry around the Cu ion. HOMO and LUMO energy values for the product complex were calculated and the optimized condition for the maximum yield of the product was determined.

Predicting Reaction Mechanisms for the Threonine-Residue Stereoinversion Catalyzed by a Dihydrogen Phosphate Ion.

The stereoinversion of amino acid residues in proteins is considered to trigger various age-related diseases. Serine (Ser) residues are relatively prone to stereoinversion. It is assumed that threonine (Thr) residues also undergo stereoinversion, which results in the formation of the d-allo-Thr residue, by the same mechanisms as those for Ser-residue stereoinversion; however, d-allo-Thr residues have not been detected in vivo. To date, although Ser-residue stereoinversion has been suggested to progress via enolization, plausible reaction mechanisms for Thr-residue stereoinversion have not been proposed. In this study, we investigated the pathway of Thr-residue enolization and successfully identified the three types of plausible reaction pathways of Thr-residue stereoinversion catalyzed by a dihydrogen phosphate ion. The geometries of reactant complexes, transition states, and enolized product complexes were optimized using B3LYP density functional methods, and single-point calculations were performed for all optimized geometries using Møller–Plesset perturbation theory to obtain reliable energies. As a result, the calculated activation energies of Thr-residue stereoinversion were 105–106 kJ mol–1, which were comparable with those of Ser-residue stereoinversion reported previously. The infrequency of Thr-residue stereoinversion may be due to other factors, such as the hydrophobicity and/or the steric hindrance of the γ-methyl group, rather than the high activation energies.

What Drives Radical Halogenation versus Hydroxylation in Mononuclear Nonheme Iron Complexes? A Combined Experimental and Computational Study.

Nonheme iron halogenases are unique enzymes in nature that selectively activate an aliphatic C–H bond of a substrate to convert it into C–X (X = Cl/Br, but not F/I). It is proposed that they generate an FeIII(OH)(X) intermediate in their catalytic cycle. The analogous FeIII(OH) intermediate in nonheme iron hydroxylases transfers OH• to give alcohol product, whereas the halogenases transfer X• to the carbon radical substrate. There remains significant debate regarding what factors control their remarkable selectivity of the halogenases. The reactivity of the complexes FeIII(BNPAPh2O)(OH)(X) (X = Cl, Br) with a secondary carbon radical (R•) is described. It is found that X• transfer occurs with a secondary carbon radical, as opposed to OH• transfer with tertiary radicals. Comprehensive computational studies involving density functional theory were carried out to examine the possible origins of this selectivity. The calculations reproduce the experimental findings, which indicate that halogen transfer is not observed for the tertiary radicals because of a nonproductive equilibrium that results from the endergonic nature of these reactions, despite a potentially lower reaction barrier for the halogenation pathway. In contrast, halogen transfer is favored for secondary carbon radicals, for which the halogenated product complex is thermodynamically more stable than the reactant complex. These results are rationalized by considering the relative strengths of the C–X bonds that are formed for tertiary versus secondary carbon centers. The computational analysis also shows that the reaction barrier for halogen transfer is significantly dependent on secondary coordination sphere effects, including steric and H-bonding interactions.

Domain architecture and catalysis of the Staphylococcus aureus fatty acid kinase

Fatty acid kinase (Fak) is a two-component enzyme that generates acyl-phosphate for phospholipid synthesis. Fak consists of a kinase domain protein (FakA) that phosphorylates a fatty acid enveloped by a fatty acid binding protein (FakB). The structural basis for FakB function has been established, but little is known about FakA. Here, we used limited proteolysis to define three separate FakA domains: the amino terminal FakA_N, the central FakA_L, and the carboxy terminal FakA_C. The isolated domains lack kinase activity, but activity is restored when FakA_N and FakA_L are present individually or connected as FakA_NL. The X-ray structure of the monomeric FakA_N captures the product complex with ADP and two Mg2+ ions bound at the nucleotide site. The FakA_L domain encodes the dimerization interface along with conserved catalytic residues Cys240, His282, and His284. AlphaFold analysis of FakA_L predicts the catalytic residues are spatially clustered and pointing away from the dimerization surface. Furthermore, the X-ray structure of FakA_C shows that it consists of two subdomains that are structurally related to FakB. Analytical ultracentrifugation demonstrates that FakA_C binds FakB, and site-directed mutagenesis confirms that a positively charged wedge on FakB meshes with a negatively charged groove on FakA_C. Finally, small angle X-ray scattering analysis is consistent with freely rotating FakA_N and FakA_C domains tethered by flexible linkers to FakA_L. These data reveal specific roles for the three independently folded FakA protein domains in substrate binding and catalysis.

Spectroscopic evidence of the effect of hydrogen peroxide excess on the coproheme decarboxylase from actinobacterial Corynebacterium diphtheriae.

The actinobacterial coproheme decarboxylase from Corynebacterium diphtheriae catalyzes the final reaction to generate heme b via the “coproporphyrin‐dependent” heme biosynthesis pathway in the presence of hydrogen peroxide. The enzyme has a high reactivity toward H2O2 used for the catalytic reaction and in the presence of an excess of H2O2 new species are generated. Resonance Raman data, together with electronic absorption spectroscopy and mass spectrometry, indicate that an excess of hydrogen peroxide for both the substrate (coproheme) and product (heme b) complexes of this enzyme causes a porphyrin hydroxylation of ring C or D, which is compatible with the formation of an iron chlorin‐type heme d species. A similar effect has been previously observed for other heme‐containing proteins, but this is the first time that a similar mechanism is reported for a coproheme enzyme. The hydroxylation determines a symmetry lowering of the porphyrin macrocycle, which causes the activation of A2g modes upon Soret excitation with a significant change in their polarization ratios, the enhancement and splitting into two components of many Eu bands, and an intensity decrease of the non‐totally symmetric modes B1g, which become polarized. This latter effect is clearly observed for the isolated ν10 mode upon either Soret or Q‐band excitations. The distal His118 is shown to be an absolute requirement for the conversion to heme d. This residue also plays an important role in the oxidative decarboxylation, because it acts as a base for deprotonation and subsequent heterolytic cleavage of hydrogen peroxide.

Asymmetric Hydroboration of Ketones by Cooperative Lewis Acid–Onium Salt Catalysis: A Quantum Chemical and Microkinetic Study to Combine Theory and Experiment

We apply microkinetic modeling in homogeneous catalysis and show how it can be used to reveal important details of a complex mechanism and how this can lead to a direct comparison between theory and experiment. While regularly used in heterogeneous catalysis, its applications to organic chemistry or homogeneous catalysis are still comparatively scarce. This approach is exemplarily applied to the mechanism of the asymmetric hydroboration of acetophenone with a highly active cooperative Lewis acid–ammonium salt catalyst. In combination with density functional theory, it is a gateway to shed light into important mechanistic details. In our study, it reveals that the counterion of the ammonium salt of the catalyst facilitates the hydride transfer step of the cycle. Chloride replacing iodide speeds up the main reaction but simultaneously has the same effect on a side reaction that consumes the product. This observation is confirmed by experimental measurements of both the main catalytic cycle and the side reaction. A sensitivity analysis showed that the transition from the product complex to the hydride transfer is rate-limiting and that it determines the enantioselectivity. Based on this insight, an enantioselective kinetic model was applied, from which the difference of the Gibbs free energy barriers of the two pathways forming the two enantiomers can be extracted. The barriers are in fairly good agreement with the ones calculated by DFT, which reveal that the asymmetric backbone interacts with the reactant sterically to favor asymmetric product formation.

ДИДЖИТАЛІЗАЦІЯ ЛОГІСТИКИ АГРОПРОДУКЦІЇ МІЖ ВЛАСНИКОМ – ГОСПОДАРЕМ ЗЕМЛІ ТА СПОЖИВАЧЕМ У СИСТЕМІ КОНТРОЛІНГУ

More than a third of Ukraine's population lives in rural areas. Possessing most of the agricultural land, they never became the real owners of their own lands. The current intellectual developments should be used, which can simplify the mechanism of production and sale of products grown in rural areas. There are many questions about mentality that are difficult to overcome to integrate the effect of scale. One of the options for a democratic form of cooperation and the use of the effect of scale is management based on the principles of cooperation. The latter operate successfully in other countries, at the same time having a profitable historical past in Ukraine during the reign of Count Andrei Sheptytsky. However, at present, it is difficult for small and medium-sized landowners to coexist in such an organizational and legal form. In addition to significant advisory work to be carried out by economists, historians, psychologists, lawyers, lawyers with rural populations, we have designed an online platform that helps remove barriers to joint business for small and medium landowners, sales of their products, delivery of products to the consumer, etc. The purpose of the article is to substantiate the sections of communication between producers and consumers created on the Internet platform, modernization of logistics processes of product delivery. The methods of deduction, induction, analysis, synthesis, dialectics, forecasting were used. In the given scientific work it is determined that the problem of establishing entrepreneurship and, at the same time, socio-economic strengthening of landowners is primarily the lack of a comprehensive understanding of the organization of business processes. The scale of these problems has led to our digitalization to such processes as: ordering and offering goods, services, technologies, investments. These are key elements that serve to organize business, in particular in the agricultural sector of the economy. It is determined that an important role in this belongs to the construction of electronic routes for delivery of products (product complex) from producer to consumer. Crucial in this is the construction of the address database of the end user. The practical significance of this development is that a competent interpretation of its inherent functionality can solve a significant number of problems of millions of landowners.

Locally Conformally Flat Doubly Twisted Product Complex Finsler Manifolds

Let be a doubly twisted product manifold of two strongly pseudoconvex complex Finsler manifolds (M1, F1) and (M2, F2). In this study, we give a characterization of locally conformally flat doubly twisted product complex Finsler manifold. We also obtain a necessary and sufficient condition for a doubly twisted product of two locally conformally flat complex Finsler manifolds to be locally conformally flat.

Applying Noise‐Based Reverse Correlation to Relate Consumer Perception to Product Complex Form Features

Consumer behavior knowledge is essential to designing successful products. However, measuring subjective perceptions affecting this behavior is a complex issue that depends on many factors. Identifying visual cues elicited by the product’s appearance is key in many cases. Marketing research on this topic has produced different approaches to the question. This paper proposes the use of Noise‐Based Reverse Correlation techniques in the identification of product form features carrying a particular semantic message. This technique has been successfully utilized in social sciences to obtain prototypical images of faces representing social stereotypes from different judgements. In this work, an exploratory study on subcompact cars is performed by applying Noise‐Based Reverse Correlation to identify relevant form features conveying a sports car image. The results provide meaningful information about the car attributes involved in communicating this idea, thus validating the use of the technique in this particular case. More research is needed to generalize and adapt Noise‐Based Reverse Correlation procedures to different product scenarios and semantic concepts.

Tris(imidazolyl) dicopper(I) complex and its reactivity to exert the catalytic oxidation of sterically hindered phenol substrates via a [Cu2O]2+ core.

The Cu ion ligated with histidine residues is a common active site motif of various Cu-containing metalloenzymes exerting versatile catalytic oxidation reactions. Due to the scarcity of structurally characterized biomimetic binuclear Cu(I)-imidazolyl complexes, the bonding interactions between the Cu(I) center and imidazolyl donor ligands as well as their stoichiometric/catalytic oxidation reactivities remain relatively unexplored. In this study, we successfully synthesized a tris(imidazolyl) dicopper(I) complex [CuI(μ-bimeta)3CuI][PF6]2 (1) characterized by single-crystal X-ray diffraction, cyclic voltammetry, and UV-vis absorption spectroscopy. The coordination environment around each Cu(I) center of complex 1 is best described as a regular trigonal geometry and the distance between two Cu(I) centers is ∼3.0521(18) Å. From the O2-/PhIO-titration reactions of complex 1, only 0.5 equiv. of O2(g) and one equiv. of PhIO are required to produce the corresponding oxygenated product complex 1ox, respectively, exhibiting a distinct UV-vis absorption band at ∼640 nm. From the characterization of ESI mass spectrometry, IR, UV-vis spectroscopy, and O2-/PhIO-titration reactions, the molecular identity of complex 1ox is tentatively assigned as [Cu(μ-O)(μ-bimeta)3Cu]2+, which is further corroborated by the spectroscopically calibrated DFT calculations. The oxidation reactivities of complex 1ox were investigated using the well-understood sterically hindered phenol substrates DTBP and TBBP in both stoichiometric and catalytic fashions. In stoichiometric reactions, one equiv. of 1ox is capable of fully converting TBBP into TBOBF in the CH3CN solution at room temperature within 1 h. The optimized selectivity of catalytically oxidizing DTBP into TBOBF (>95% selectivity, ∼100% conversion rate) could be achieved with a 10 mol% loading of complex 1ox using air as the oxidant. From the time-course product distributions of this catalyst system, ∼40% of DTBP was converted into the corresponding TBBP product in the first 5 min. From 10 to 120 min, the oxidation of DTBP to TBBP and the oxidation of TBBP to TBOBF simultaneously proceeded, which was evidenced by the decrease of TBBP and the increase TBOBF.

Imitation of β-lactam binding enables broad-spectrum metallo-β-lactamase inhibitors.

Carbapenems are vital antibiotics, but their efficacy is increasingly compromised by metallo-β-lactamases (MBLs). Here we report the discovery and optimization of potent broad-spectrum MBL inhibitors. A high-throughput screen for NDM-1 inhibitors identified indole-2-carboxylates (InCs) as potential β-lactamase stable β-lactam mimics. Subsequent structure-activity relationship studies revealed InCs as a new class of potent MBL inhibitor, active against all MBL classes of major clinical relevance. Crystallographic studies revealed a binding mode of the InCs to MBLs that, in some regards, mimics that predicted for intact carbapenems, including with respect to maintenance of the Zn(II)-bound hydroxyl, and in other regards mimics binding observed in MBL-carbapenem product complexes. InCs restore carbapenem activity against multiple drug-resistant Gram-negative bacteria and have a low frequency of resistance. InCs also have a good in vivo safety profile, and when combined with meropenem show a strong in vivo efficacy in peritonitis and thigh mouse infection models.

Spin-Spin Coupling Controls the Gas-Phase Reactivity of Aromatic σ-Type Triradicals.

Examination of the reactions of σ-type quinolinium-based triradicals with cyclohexane in the gas phase demonstrated that the radical site that is the least strongly coupled to the other two radical sites reacts first, independent of the intrinsic reactivity of this radical site, in contrast to related biradicals that first react at the most electron-deficient radical site. Abstraction of one or two H atoms and formation of an ion that formally corresponds to a combination of the ion and cyclohexane accompanied by elimination of a H atom ("addition-H") were observed. In all cases except one, the most reactive radical site of the triradicals is intrinsically less reactive than the other two radical sites. The product complex of the first H atom abstraction either dissociates to give the H-atom-abstraction product and the cyclohexyl radical or the more reactive radical site in the produced biradical abstracts a H atom from the cyclohexyl radical. The monoradical product sometimes adds to cyclohexene followed by elimination of a H atom, generating the "addition-H" products. Similar reaction efficiencies were measured for three of the triradicals as for relevant monoradicals. Surprisingly, the remaining three triradicals (all containing a meta-pyridyne moiety) reacted substantially faster than the relevant monoradicals. This is likely due to the exothermic generation of a meta-pyridyne analog that has enough energy to attain the dehydrocarbon atom separation common for H-atom-abstraction transition states of protonated meta-pyridynes.