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We synthesized a new iodoargentate [Co(2,2′-bipy)3]Ag3I6 (1) (2,2′-bipy = 2,2′-bipyridine) via the reaction of AgI, KI, 2,2′-bipy and Co(NO3)2 in dimethylformamide (DMF) solvent at room temperature. The [Co(2,2′-bipy)3]3+ complex cation directs the formation of the 0 D cluster [Ag3I6]3− anion that features an irregular double-level gear wheel with a maximum diameter of 5.512 Å. The iodoargentate possesses the characteristics of semiconductors with a band gap of 2.03 eV. It exhibits excellent ion-exchange behavior for adsorbing crystal violet (CV) and methylene blue (MB), and it can function as a promising photocatalyst for degrading rhodamine B (RhB). The improved photocatalytic activity can be ascribed to the hole structure in the anions of iodoargentates. [ABSTRACT FROM AUTHOR]

CO2 hydrogenation into value-added chemicals not only offer an economically beneficial outlet but also help reduce the emission of greenhouse gases. Herein, the density functional theory (DFT) studies have been carried out on CO2 hydrogenation reaction for formamide production catalyzed by two different N–H ligand types of PNP iron catalysts. The results suggest that the whole mechanistic pathway has three parts: (i) precatalyst activation, (ii) hydrogenation of CO2 to generate formic acid (HCOOH), and (iii) amine thermal condensation to formamide with HCOOH. The lower turnover number (TON) of a bifunctional catalyst system in hydrogenating CO2 may attribute to the facile side-reaction between CO2 and bifunctional catalyst, which inhibits the generation of active species. Regarding the bifunctional catalyst system addressed in this work, we proposed a ligand participated mechanism due to the low pKa of the ligand N–H functional in the associated stage in the catalytic cycle. Remarkably, catalysts without the N–H ligand exhibit the significant transfer hydrogenation through the metal centered mechanism. Due to the excellent catalytic nature of the N–H ligand methylated catalyst, the N–H bond was not necessary for stabilizing the intermediate. Therefore, we confirmed that N–H ligand methylated catalysts allow for an efficient CO2 hydrogenation reaction compared to the bifunctional catalysts. Furthermore, the influence of Lewis acid and strong base on catalytic N-formylation were considered. Both significantly impact the catalytic performance. Moreover, the catalytic activity of PNMeP-based Mn, Fe and Ru complexes for CO2 hydrogenation to formamides was explored as well. The energetic span of Fe and Mn catalysts are much closer to the precious metal Ru, which indicates that such non-precious metal catalysts have potentially valuable applications. [ABSTRACT FROM AUTHOR]

Graphical abstract The C H activation step proceeds under the concerted metalation deprotonation mechanism. The regioselectivity for different C H activation sites is dependent on the coordination structure of the Rh(III) complex. The preferred C H activation pathway involves the lowest energy of transition state. Correspondingly, the regioselectivity is controlled both kinetically and thermodynamically. Highlights • The regioselectivity is dependent on the coordination structure of Rh(III) complex. • The regioselectivity is controlled both kinetically and thermodynamically. • The chemoselectivity is decided by the apparent activation energies (ΔG) of catalytic reaction. Abstract The mechanism of rhodium(III)-catalyzed C H functionalization of o -vinylphenols (1a) with alkynes has been investigated with DFT calculations. The results suggest the whole reaction is comprised with four stages: (I) O H deprotonation, (II) C H activation induced by Rh(III) catalyst interacting with o -vinylphenols, (III) alkyne coordination and (IV) regeneration of Rh(III) catalyst. The C H activation step proceeds under the concerted metalation deprotonation mechanism. The regioselectivity and chemoselectivity of the reaction also have been discussed, respectively. The regioselectivity for different C H activation sites is depended on the coordination structure of the related Rh(III) complex. In addition, when the substrates are substituted with alkyl (or alkenes) at the terminal position of the alkene, such as (E)-2-(prop-1-en-1-yl)phenol 1b and 2-allylphenol 1c , the apparent activation energies (ΔG) are obviously higher than that of 1a , which indicates that they are unfavorable to occur. The effect of CO 2 Me substituent on the para position to the hydroxyl (1d) is also investigated. [ABSTRACT FROM AUTHOR]

Theoretical calculation has been carried out for the nucleophilic displacement reaction of 1,2-dichloroethane catalyzed by haloalkane dehalogenase. The results indicate that different hydrogen bond patterns of the oxyanion hole and the halide-stabilizing residues play an important role in the dehalogenation reaction. They cause concertedly an earlier transition state (TS) with the activation barrier of 16.60 kcal/mol. The stabilization effect of Trp125 and Trp175 on chlorine atom in the TS is larger than that of the reactant complex by 15.67 kcal/mol so that, they make contribution to the stabilization of the TS. Moreover, the reaction shows the enzymatic action can be attributed to a combination of reactant-state destabilization and transition-state electrostatic stabilization. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011 [ABSTRACT FROM AUTHOR]

We synthesized a new iodoargentate [Co(2,2'-bipy) 3 ]Ag 3 I 6 (1) (2,2'-bipy = 2,2'-bipyridine) via the reaction of AgI, KI, 2,2'-bipy and Co(NO 3 ) 2 in dimethylformamide (DMF) solvent at room temperature. The [Co(2,2'-bipy) 3 ] 3+ complex cation directs the formation of the 0 D cluster [Ag 3 I 6 ] 3- anion that features an irregular double-level gear wheel with a maximum diameter of 5.512 Å. The iodoargentate possesses the characteristics of semiconductors with a band gap of 2.03 eV. It exhibits excellent ion-exchange behavior for adsorbing crystal violet (CV) and methylene blue (MB), and it can function as a promising photocatalyst for degrading rhodamine B (RhB). The improved photocatalytic activity can be ascribed to the hole structure in the anions of iodoargentates.

CO2 hydrogenation into value-added chemicals not only offer an economically beneficial outlet but also help reduce the emission of greenhouse gases. Herein, the density functional theory (DFT) studies have been carried out on CO2 hydrogenation reaction for formamide production catalyzed by two different N-H ligand types of PNP iron catalysts. The results suggest that the whole mechanistic pathway has three parts: (i) precatalyst activation, (ii) hydrogenation of CO2 to generate formic acid (HCOOH), and (iii) amine thermal condensation to formamide with HCOOH. The lower turnover number (TON) of a bifunctional catalyst system in hydrogenating CO2 may attribute to the facile side-reaction between CO2 and bifunctional catalyst, which inhibits the generation of active species. Regarding the bifunctional catalyst system addressed in this work, we proposed a ligand participated mechanism due to the low pKa of the ligand N-H functional in the associated stage in the catalytic cycle. Remarkably, catalysts without the N-H ligand exhibit the significant transfer hydrogenation through the metal centered mechanism. Due to the excellent catalytic nature of the N-H ligand methylated catalyst, the N-H bond was not necessary for stabilizing the intermediate. Therefore, we confirmed that N-H ligand methylated catalysts allow for an efficient CO2 hydrogenation reaction compared to the bifunctional catalysts. Furthermore, the influence of Lewis acid and strong base on catalytic N-formylation were considered. Both significantly impact the catalytic performance. Moreover, the catalytic activity of PNMeP-based Mn, Fe and Ru complexes for CO2 hydrogenation to formamides was explored as well. The energetic span of Fe and Mn catalysts are much closer to the precious metal Ru, which indicates that such non-precious metal catalysts have potentially valuable applications.

The mechanism of B(C 6 F 5 ) 3 promoted Cp*Co III -catalyzed C-H functionalization was investigated in detail employing density functional theory (DFT). The formation free energy of every possible species in the multicomponent complex system was explored and the optimal active catalyst was screened out. The results uncover the role of B(C 6 F 5 ) 3 played in forming active catalyst is from the coordination with OAc - , but not from the formation of [I(C 6 F 5 ) 3 B] - , and no acceleration effect is found in C-H activation as well as the formation of Co III -carbene intermediate. Moreover, present theoretical results elucidate the Cp*Co III -catalyzed C-H activation is mediated by imine N-coordination other than general proposed the sequence of N-deprotonation directed C-H activation. The metal-controlled C-H/N-H selectivity was then elucidated by insighting into [Cp*Co III OAc] + /[Cp*Rh III OAc] + -catalyzed C-H and N-H activations, respectively.