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Fe(III) and Mn(II) complexes with condensation product of thiosemicarbazide and 2-acetylthiazole (HL1, (E)-2-(1-(thiazol-2-yl)ethylidene)hydrazine-1-carbothioamide) have been synthesized and characterized by single-crystal X-ray diffraction, IR spectroscopy, and elemental analysis. In both complexes, the thiosemicarbazone ligand is coordinated in deprotonated form through the NNS donor set of atoms. However, while Fe(III) complex is in the doublet ground state with distorted octahedral geometry, the coordination environment around Mn(II) is distorted trigonal-prismatic, and the sextet state is found to be the ground state. DFT calculations were performed to rationalize spin state preferences, and continuous shape measure describes the deviation from ideal six-coordinated polyhedral geometries in the ground and excited states. Antimicrobial activity (against a panel of Gram-negative and Gram-positive bacteria, two yeast, and one fungal strain), brine shrimp assay, and DPPH radical scavenging activity of both complexes were evaluated, and these results relate to the electronic structure of the complexes. This is the peer-reviewed, authors’ version of the article: Stojičkov, M., Zlatar, M., Mazzeo, P. P., Bacchi, A., Radanović, D., Stevanović, N., Jevtović, M., Novaković, I., Anđelković, K., Sladić, D., Čobeljić, B., Gruden, M. (2023). The interplay between spin states, geometries and biological activity of Fe(III) and Mn(II) complexes with thiosemicarbazone. Polyhedron, 237, 116389. [https://doi.org/10.1016/j.poly.2023.116389] The published version: [https://cer.ihtm.bg.ac.rs/handle/123456789/6041] Supplementary information: [https://cer.ihtm.bg.ac.rs/handle/123456789/6043]

International audience; This Editorial by Guest Editors L. Rulíšek, M. Gruden, M. Orio and QBIC Society President R. J. Deeth summarizes the Chemistry Europe Special Collection on quantum bioinorganic chemistry, published in collaboration with the Quantum Bioinorganic Chemistry (QBIC) Society. The Collection, which recognizes of the strides made in this area of research, spans several of our portfolio journals Chemistry—A European Journal, the European Journal of Inorganic Chemistry, ChemPlusChem, ChemBioChem, ChemPhysChem, and ChemistryOpen, includes outstanding work in the field by authors across the world and we hope you enjoy reading them!

Binuclear double end-on azido bridged Ni(II) complex (1) with composition [Ni2L2(?-1,1-N3)2(N3)2]?6H2O, (L = (E)-N,N,N-trimethyl-2-oxo-2-(2- -(1-(pyridin-2-yl)ethylidene)hydrazinyl)ethan-1-amin) was synthesized and characterized by single-crystal X-ray diffraction method. Ni(II) ions are hexacoordinated with the tridentate heteroaromatic hydrazone-based ligand and three azido ligands (one terminal and two are end-on bridges). DFT calculations revealed that coupling between two Ni(II) centers is ferromagnetic in agreement with binuclear Ni(II) complexes with similar structures.

Two Co(III) complexes with condensation product of thiosemicarbazide and 2-acetylthiazole (HL1 ligand, (E)-2-(1-(thiazol-2-yl)ethylidene)hydrazine-1-carbothioamide) and the condensation product of 2-acetylpyridine and Girard's P reagent (HL2Cl ligand, (E)-1-(2-oxo-2-(2-(1-(pyridin-2-yl)ethylidene)hydrazinyl)ethyl)pyridin-1-ium chloride) have been synthesized and characterized based on the results of single-crystal X-ray diffraction, NMR and IR spectroscopy and elemental analysis. Cobalt(III) complex with HL1 ligand, [Co(L1)2]BF4⋅H2O (1), is bis octahedral complex in which two deprotonated ligand molecules coordinate in a mer arrangement through two NNS sets of donor atoms. In cobalt(III) complex with HL2Cl, [Co(L2)(N3)3] (2), the ligand is coordinated in deprotonated, formally neutral, form to Co(III) ion in tridentate fashion through NNO set of donor atoms, and the other three coordination sites of a monokis octahedron are occupied by meridionally coordinated azide anions. DFT calculations were performed to elucidate coordination preferences of these ligands toward Co(III) ion. This is an accepted version of the manuscript: Darmanović, D., Radanović, D., Jevtović, M., Turel, I., Pevec, A., Milčić, M., Gruden, M., Zlatar, M., Đorđević, N., Anđelković, K.,& Čobeljić, B.. (2022) "Coordination preferences of NNO and NNS Schiff base ligands with Co(III) complexes: Synthesis, characterization and DFT calculation," Journal of Molecular Structure Elsevier., 133509. doi: [https://doi.org/10.1016/j.molstruc.2022.133509] Supplementary material: [https://cer.ihtm.bg.ac.rs/handle/123456789/5112] Crystallographic data (CCDC 2168741): [https://cer.ihtm.bg.ac.rs/handle/123456789/5110] Crystallographic data (CCDC 2168742): [https://cer.ihtm.bg.ac.rs/handle/123456789/5111] Published version: [https://cer.ihtm.bg.ac.rs/handle/123456789/5113]

In this paper, Cu(II), Mn(II) and Zn(II) complexes with N,N,N-trimethyl-2-oxo-2-(2-(1-(thiazol-2-yl)ethylidene)hydrazinyl)ethan-1-aminium chloride (HL1Cl) were synthesized and characterized by single-crystal X-ray diffraction, IR spectroscopy, elemental analysis and DFT calculations. In all three complexes, a ligand (L1) is coordinated in a deprotonated formally neutral zwitterionic form via NNO donor set atoms. Cu(II) and Zn(II) form mononuclear penta-coordinated complexes [CuL1(N3)(CH3OH)]BF4 and [ZnL1(N3)2], respectively, while Mn(II) forms a binuclear [Mn2L12(μ-1,1-N3)2(N3)2]·2CH3OH complex, with unusual distorted trigonal-prismatic geometry around the metal centers. The antimicrobial activity of these complexes was tested against a panel of Gram-negative and Gram-positive bacteria, two yeasts and one fungal strain. The binuclear Mn(II) complex showed antifungal activity of similar intensity to amphotericin B. Based on the results of the brine shrimp test and DPPH radical scavenging activity, the most active Cu(II) and Mn(II) complexes were selected for evaluation of cytotoxic activity against five malignant cancer cell lines (HeLa, A375, MCF7, PC-3 and A549) and one normal cell line HaCaT. Both complexes showed significant activity. It should be pointed out that the activity of the Mn(II) complex against the MCF7 breast cancer cell line is only slightly weaker than that of cisplatin, but with selectivity to the tumor cell line in comparison to normal HaCaT cells, which is non-existent in the case of cisplatin. Supporting information: [https://cer.ihtm.bg.ac.rs/handle/123456789/4902] Related crystallographic data (CCDC 2110386): [https://cer.ihtm.bg.ac.rs/handle/123456789/4903] Related crystallographic data (CCDC 2110387): [https://cer.ihtm.bg.ac.rs/handle/123456789/4904] Related crystallographic data (CCDC 2110388): [https://cer.ihtm.bg.ac.rs/handle/123456789/4905]

In this review, а density functional theory (DFT) procedure is presented to calculate the Jahn–Teller (JT) parameters in a non-empirical way, which does not depend on the system at hand. Moreover, the intrinsic distortion path (IDP) model that gives further insight into the mechanism of the distortion is presented. The summarized results and their comparison to experimentally estimated values and high-level ab initio calculations, not only prove the good ability of the used approach, but also provide many answers to the intriguing behavior of JT active molecules. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 172035]

In this work we present the synthesis, and experimental and theoretical analysis of a binuclear nickel(II) complex coordinated to a new phthalazine dihydrazone-based ligand. Single-crystal X-ray diffraction analysis of the metal complex shows that the coordination geometry around each nickel(II) atom is distorted octahedral. DFT calculations predict that the magnetic exchange coupling constant of the binuclear nickel(II) complex is predominantly anti-ferromagnetic. Supplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/3317]

The Pd-catalyzed N-arylation method for the synthesis of eighteen

The Pd-catalyzed N-arylation method for the synthesis of eighteen N,1-diaryl-1H-tetrazol-5-amine derivatives is reported. By running the reactions at 35 °C, compounds were isolated as single isomers since the undesired Dimroth rearrangement was completely suppressed. Furthermore, the Dimroth rearrangement of N,1-diaryl-1H-tetrazol-5-amines was rationalized by conducting comprehensive experiments and NMR analysis as well as density functional theory (DFT) calculations of thermodynamic stability of the compounds. It was established that the Dimroth rearrangement is thermodynamically controlled, and the equilibrium of the reaction is determined by the stability of the corresponding isomers. The mechanism was investigated by additional DFT calculations, and the opening of the tetrazole ring was shown to be the rate-determining step. By maneuvering Pd-catalyzed N-arylation and the subsequent Dimroth rearrangement, two more N,1-diaryl-1H-tetrazol-5-amine derivatives were acquired, which otherwise cannot be synthesized by employing the C–N cross-coupling reaction. This is the peer-reviewed, authors’ version of the article: Nikolić, A., Stanić, J., Zlatar, M., Gruden, M., Anđelković, B., Selaković, Ž., Ajdačić, V.,& Opsenica, I. (2021). Controlling Pd-Catalyzed N-Arylation and Dimroth Rearrangement in the Synthesis of N,1-Diaryl-1H-tetrazol-5-amines. The Journal of Organic Chemistry, American Chemical Society (ACS)., 86(6), 4794-4803. [https://doi.org/10.1021/acs.joc.1c00282] This document is the Accepted Manuscript version of a Published Work that appeared in final form in The Journal of Organic Chemistry, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see [https://doi.org/10.1021/acs.joc.1c00282] The published version: [https://cherry.chem.bg.ac.rs/handle/123456789/4358] The supporting information: [https://cherry.chem.bg.ac.rs/handle/123456789/4360]

To improve the description of interactions among the localized d, f electrons in transition metals, we have introduced a ligand-field motivated contribution into the Density Functional Tight Binding (DFTB) model. Referred to as DFTB3+U, the approach treats the d, f electron repulsions with rotationally invariant orbital-orbital interactions and a Hartree-Fock model; this represents a major conceptual improvement over the original DFTB3 approach, which treats the d, f -shell interactions in a highly averaged fashion without orbital level of description. The DFTB3+U approach is tested using a series of nickel compounds that feature Ni(II) and Ni(III) oxidation states. By using parameters developed with the original DFTB3 Hamiltonian and empirical +U parameters (F(0/2/4) Slater integrals), we observe that the DFTB3+U model indeed provides substantial improvements over the original DFTB3 model for a number of properties of the nickel compounds, including the population and spin polarization of the d-shell, nature of the frontier orbitals, ligand field splitting and the energy different between low and high spin states at OPBE optimized structures. This proof-of-concept study suggests that with self-consistent parameterization of the electronic and +U parameters, the DFTB3+U model can develop into a promising model that can be used to efficiently study reactive events involving transition metals ion condensed phase systems. The methodology can be integrated with other approximate QM methods as well, such as the extended tight binding (xTB) approach.

To improve the description of interactions among the localized d, f electrons in transition metals, we have introduced a ligand-field motivated contribution into the Density Functional Tight Binding (DFTB) model. Referred to as DFTB3+U, the approach treats the d, f electron repulsions with rotationally invariant orbital–orbital interactions and a Hartree–Fock model; this represents a major conceptual improvement over the original DFTB3 approach, which treats the d, f-shell interactions in a highly averaged fashion without orbital level of description. The DFTB3+U approach is tested using a series of nickel compounds that feature Ni(II) and Ni(III) oxidation states. By using parameters developed with the original DFTB3 Hamiltonian and empirical +U parameters (F0/2/4 Slater integrals), we observe that the DFTB3+U model indeed provides substantial improvements over the original DFTB3 model for a number of properties of the nickel compounds, including the population and spin polarization of the d-shell, nature of the frontier orbitals, ligand field splitting and the energy different between low and high spin states at OPBE optimized structures. This proof-of-concept study suggests that with self-consistent parameterization of the electronic and +U parameters, the DFTB3+U model can develop into a promising model that can be used to efficiently study reactive events involving transition metals ion condensed phase systems. The methodology can be integrated with other approximate QM methods as well, such as the extended tight binding (xTB) approach.

In the present work, we examine the magnetic properties of 8 "end-to-end" thiocyanato, and 3 "end-to-end" cyanato double bridged Ni(II) binu­cle­ar complexes. Thiocyanato complexes are weakly ferromagnetic. Cyanato brid­ged complexes exhibit weak antiferromagnetic coupling. There­fore, it is a challenge for computational chemistry to calculate the exchange coupling constant in these systems accurately. 17 different Density Functional Approximations with different flavors are used to find the method of choice to study magnetic properties in binuclear Ni(II) complexes within the Broken-Symmetry approach. It is found that M06-2X and PWPB95 performed the best compared to experimental values for the entire set of examined complexes. Furthermore, the magneto-structural correlation rationalizes the results. У овом раду, проучавана су магнетна својства 8 "end-to-end" тиоцијанато, и 3 "end-to-end" цијанато двоструко премошћених Ni(II) бинуклеарних комплекса. Tиоцијанато премошћени комплекси су слабо феромагнетни. Комплекси премошћени цијанато лигандима показују слабо антиферомагнетно купловање. Због тога је прецизно израчунавање константи купловања у овим системима изазов за рачунарску хемију. Константе купловања у овим системима су израчунате Broken-Symmetry приступом у оквиру Теорије функционала густине. 17 апроксимативних функционала густине су коришћени како би се пронашао најпоузданији ниво теорије за проучавање магнетних својстава бинуклеарних Ni(II) комплекса. Утврђено је да су M06-2X и PWPB95 показали најбоље слагање са експерименталним вредностима за цео скуп испитиваних комплекса. Напослетку, резултати су рационализовани магнетно-структурном корелацијом. This is the peer-reviewed version of the article: M. Zlatar, F. Vlahović, D. Mitić, M. Zlatović, M. Gruden, J. Serb. Chem. Soc. (2020) [https://doi.org/10.2298/JSC201106071Z] The published version: [https://cer.ihtm.bg.ac.rs/handle/123456789/4041]

Two binuclear double end-on azido bridged Ni(II) complexes, [Ni2L2(μ-1,1-N3)2(N3)2]⋅2H2O (1a), and [Ni2L2(μ-1,1-N3)2(N3)2]⋅4H2O (1b) having the same inner sphere, where L=((E)-N,N,N-trimethyl-2-oxo-2-(2-(1-(thiazol-2-yl)ethylidene)hydrazinyl)ethan-1-aminium, were synthesized from the same solution and characterized by single-crystal X-ray diffraction methods. Variable‐temperature magnetic susceptibility measurements showed intra-dimer ferromagnetic coupling between Ni(II) ions. The ferromagnetic coupling is supported by the broken-symmetry DFT calculations, with the level of theory chosen based on a benchmark study on 19 additional structurally related binuclear Ni(II) complexes. The role of water molecules in crystals of 1a and 1b is explained by DFT based energy decomposition analysis. This is the peer-reviewed, authors’ version of the article: Keškić, T.; Jagličić, Z.; Pevec, A.; Čobeljić, B.; Radanović, D.; Gruden, M.; Turel, I.; Anđelković, K.; Brčeski, I.; Zlatar, M. Synthesis, X-Ray Structures and Magnetic Properties of Ni(II) Complexes of Heteroaromatic Hydrazone. Polyhedron 2020, 191, 114802. [https://doi.org/10.1016/j.poly.2020.114802] Published version: [http://cer.ihtm.bg.ac.rs/handle/123456789/3684] Supplementary data: [https://cer.ihtm.bg.ac.rs/handle/123456789/4439] Crystallographic data (CCDC 2009327): [https://cer.ihtm.bg.ac.rs/handle/123456789/4441] Crystallographic data (CCDC 2009328): [https://cer.ihtm.bg.ac.rs/handle/123456789/4440]

This chapter provides an introduction to the electronic structure of coordination compounds. The introduction and overview of quantum chemistry, electronic structure of atoms, ligand field theory, and computational chemistry of transition metal compounds are given.

The isothiocyanato Zn(II) complex (1) and mixed isothiocyanato/thiocyanato Cd(II) complex (2) with the condensation product of 2-acetylpyridine and trimethylammoniumacetohydrazide chloride (Girard’s T reagent) (HLCl) were investigated both experimentally and theoretically. The crystal structures of both complexes showed tridentate N2O coordination of hydrazine ligand. In complex 1 square-pyramidal coordination surrounding of Zn(II) consists of deprotonated hydrazone ligand and two isothiocyanato ligands, while in octahedral Cd(II) complex ligand is coordinated without deprotonation as a positively charged species and coordination geometry is completed with two N-coordinated and one S-coordinated NCS− anions. NMR spectroscopy and molar conductivity results for Cd(II) and Zn(II) complexes indicated their instability in solution. DFT calculations were performed to explain coordination preference and stability of complexes 1 and 2 in solid state and in solution. The obtained Cd(II) complex is the first reported mononuclear pseudohalide/halide Cd(II) complex with quinoline-/pyridine-based hydrazone ligands possessing octahedral geometry in solid state. In this complex, H-bonding has significant impact on coordination number and supramolecular assembly in solid state. © 2018, Springer Science+Business Media, LLC, part of Springer Nature. Supplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/3305]

Non-heme (L)Fe-III and (L)Fe-III-O-Fe-III(L) complexes (L=1,1-di(pyridin-2-yl)-N,N-bis(pyridin-2-ylmethyl)-ethan-1-amine) underwent reduction under irradiation to the Fe-II state with concomitant oxidation of methanol to methanal, without the need for a secondary photosensitizer. Spectroscopic and DFT studies support a mechanism in which irradiation results in charge-transfer excitation of a Fe-III-mu-O-Fe-III complex to generate [(L)Fe-IV=O](2+) (observed transiently during irradiation in acetonitrile), and an equivalent of (L)Fe-II. Under aerobic conditions, irradiation accelerates reoxidation from the Fe-II to the Fe-III state with O-2, thus closing the cycle of methanol oxidation to methanal.

We report here a computational study on a series of FeII, FeIIIand FeIVhydroxo/oxo-iron complexes with a broad palette of ligands. We are interested in assessing the robustness of widely used density functionals for their prediction and description of structures and spin states for the examined oxoiron complexes. We have used a variety of density functional approximations (S12g, LDA, BP86-D3, OPBE, SSB-D, B3LYP-D3, S12h and MVS), in all cases including solvation and relativistic effects explicitly. One of the main observations of this detailed study is the excellent performance of S12g for both accurate structures and spin state splittings. Moreover, our results show that in general all density functionals can be used as a reliable computational tool for reproducing and predicting geometries, determining the oxidation state of iron, and most are able as well to providing good descriptions of spin state energetics.

Although the unusual structural, magnetic,electronic, and spin characteristics of manganocene hasintrigued scientists for decades, a unified explanation andrationalization of its properties has not yet been provided.Results obtained by Multideterminantal Density Functional Theory (MD-DFT), Energy Decomposition Analysis (EDA), and Intrinsic Distortion Path (IDP) methodologies indicate how this uniqueness can be traced back tothe manganocene’s peculiar electronic structure, mainly,the degenerate ground state and close-lying electronic andspin states. This is the peer-reviewed, authors’ version of the article: Stepanović, S., Zlatar, M., Swart, M.,& Gruden, M. (2019). The Irony of Manganocene: An Interplay between the Jahn-Teller Effect and Close-Lying Electronic and Spin States. Journal of Chemical Information and Modeling, American Chemical Society (ACS), 59(5), 1806-1810. [https://doi.org/10.1021/acs.jcim.8b00870] This document is the Accepted Manuscript version of a Published Work that appeared in final form in Journal of Chemical Information and Modeling, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see [https://doi.org/10.1021/acs.jcim.8b00870] The published version: [http://cer.ihtm.bg.ac.rs/handle/123456789/2894] Supplementary data: [https://cer.ihtm.bg.ac.rs/handle/123456789/4446]

The reaction of (E)-N,N,N-trimethyl-2-oxo-2-(2-(1-(pyridin-2-yl)ethylidene)hydrazinyl)ethan-1-aminium-chloride (HLCl) with copper(II) perchlorate led to mononuclear [CuLCl]ClO 4 complex (1). The same reaction with excess of sodium azide gives dinuclear azido double end-on bridged Cu(II) complex [Cu 2 L 2 (μ- 1,1 -N 3 ) 2 ](ClO 4 ) 2 (2). In both complexes hydrazone ligand is NNO coordinated in monodeprotonated formally neutral zwitter-ionic form. Complexes were characterized by elemental analysis, IR spectroscopy and single-crystal X-ray crystallography. Variable‐temperature magnetic susceptibility measurements for dinuclear Cu(II) complex showed intra-dimer ferromagnetic coupling between Cu(II) ions (J = 7.4 cm −1 ). DFT-BS calculations provided explanation for magnetic properties of dinuclear Cu(II) complex. Both complexes were shown to highly efficiently catalyze the N-arylation of imidazole and benzimidazole with electron-poor or electron-rich aryl iodides, under user-friendly and sustainable conditions. This is the peer-reviewed version of the following article: Milenković, M. R.; Papastavrou, A. T.; Radanović, D.; Pevec, A.; Jagličić, Z.; Zlatar, M.; Gruden, M.; Vougioukalakis, G. C.; Turel, I.; Anđelković, K.; et al. Highly-Efficient N-Arylation of Imidazole Catalyzed by Cu(II) Complexes with Quaternary Ammonium-Functionalized 2-Acetylpyridine Acylhydrazone. Polyhedron 2019, 165, 22–30. [https://doi.org/10.1016/j.poly.2019.03.001] Supplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/3006]

In this work, we explore the applicability and limitations of the current third order density functional tight binding (DFTB3) formalism for treating transition metal ions using nickel as an example. To be consistent with recent parameterization of DFTB3 for copper, the parametrization for nickel is conducted in a spin-polarized formulation and with orbital-resolved Hubbard parameters and their charge derivatives. The performance of the current parameter set is evaluated based on structural and energetic properties of a set of nickel-containing compounds that involve biologically relevant ligands. Qualitatively similar to findings in previous studies of copper complexes, the DFTB3 results are more reliable for nickel complexes with neutral ligands than for charged ligands; nevertheless, encouraging agreement is noted in comparison to the reference method, B3LYP/aug-cc-pVTZ, especially for structural properties, including cases that exhibit Jahn–Teller distortions; the structures also compare favorably to available X-ray data in the Cambridge Crystallographic Database for a number of nickel-containing compounds. As to limitations, we find it is necessary to use different d shell Hubbard charge derivatives for Ni(I) and Ni(II), due to the distinct electronic configurations for the nickel ion in the respective complexes, and substantial errors are observed for ligand binding energies, especially for charged ligands, d orbital splitting energies and splitting between singlet and triplet spin states for Ni(II) compounds. These observations highlight that future improvement in intra-d correlation and ligand polarization is required to enable the application of the DFTB3 model to complex transition metal ions. © 2018 Wiley Periodicals, Inc. © 2018 Wiley Periodicals, Inc.

The reaction of (E)-N,N,N-trimethyl-2-oxo-2-(2-(1-(pyridin-2-yl)ethylidene)hydrazinyl)ethan-1-aminium-chloride (HLCl) with copper(II) perchlorate led to mononuclear [CuLCl]ClO4 complex (1). The same reaction with excess of sodium azide gives dinuclear azido double end-on bridged Cu(II) complex [Cu2L2(μ-1,1-N3)2](ClO4)2 (2). In both complexes hydrazone ligand is NNO coordinated in monodeprotonated formally neutral zwitter-ionic form. Complexes were characterized by elemental analysis, IR spectroscopy and single-crystal X-ray crystallography. Variable‐temperature magnetic susceptibility measurements for dinuclear Cu(II) complex showed intra-dimer ferromagnetic coupling between Cu(II) ions (J = 7.4 cm−1). DFT-BS calculations provided explanation for magnetic properties of dinuclear Cu(II) complex. Both complexes were shown to highly efficiently catalyze the N-arylation of imidazole and benzimidazole with electron-poor or electron-rich aryl iodides, under user-friendly and sustainable conditions. © 2019 Elsevier Ltd

The decarbonylative dibromination of 2-thiophenecarboxaldehyde derivatives with bromine under mild conditions is developed. The mechanism for the decarbonylation is investigated by experimental and instrumental techniques and is extended by a computational study. Alongside removal of the formyl group, this method enables functionalization of the starting compounds in a single reaction step, which can be further exploited for the synthesis of 2,5-diaryl-3-bromothiophenes and 2,3,5-triarylthiophenes. Supplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/3435]

Non-heme iron(II) complexes of pentadentate N4Py (N,N-bis(2-pyridylmethyl)-N-bis(2-pyridyl)methylamine) type ligands undergo visible light-driven oxidation to their iron(III) state in the presence of O2 without ligand degradation. Under mildly basic conditions, however, highly selective base catalyzed ligand degradation with O2, to form a well-defined pyridyl-imine iron(II) complex and an iron(III) picolinate complex, is accelerated photochemically. Specifically, a pyridyl-CH2 moiety is lost from the ligand, yielding a potentially N4 coordinating ligand containing an imine motif. The involvement of reactive oxygen species other than O2 is excluded; instead, deprotonation at the benzylic positions to generate an amine radical is proposed as the rate determining step. The selective nature of the transformation holds implications for efforts to increase catalyst robustness through ligand design., Photoaccelerated oxidation of an aminopyridyl ligand bound to an Fe(III) ion to a well-defined imine-based Fe(II) complex involves initial alkyl C−H deprotonation followed by reaction with O2 to form an alkyl peroxyl radical. Intramolecular C−H abstraction followed by C−N bond cleavage yields picoline aldehyde and a pyridyl-imine complex. The selectivity of the reaction prevents further oxidation and holds implications for ligand degradation under conditions used in oxidation catalysis with peroxides.

The complexes [(FeLX)-X-N2S2] [in which L-N2S2 = 2,2'-(2,2'-bipryridine-6,6'-diyl)bis(1,1'-diphenylethanethiolate) and X = Cl, Br and I], characterized crystallographically earlier and here (Fe(L)Br), reveal a square pyramidal coordinated Fe-III ion. Unusually, all three complexes have intermediate spin ground states. Susceptibility measurements, powder cw X- and Q-band EPR spectra, and zero-field powder Mossbauer spectra show that all complexes display distinct magnetic anisotropy, which has been rationalized by DFT calculations. Supplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/3204]

Analysis of the multimode Jahn-Teller (JT) distortion in anions and cations of corannulene and coronene is presented, combining multideterminantal-DFT (MD-DFT) and Intrinsic Distortion Path (IDP) methods. The JT distortion is derived from the sum of contributions of all possible JT active normal modes. The C-C stretching modes play the most important role in the stabilization of the systems, in all investigated species, pushing the nuclei toward the minima on the potential energy surface. The further inspection of the IDP revealed that the relaxation of the geometry arrives in the final part of the path and is encountered by the softest vibrational modes. The same trend was observed in cyclopentadienyl radical, benzene anion, benzene cation and fullerene ions. This gives microscopic origin into the mechanism of the distortion and provides general behavior of the JT effect in these similar molecules. Moreover, MD-DFT and IDP, as fast and fully non-empirical approaches, can be considered as a reliable tool for better understanding of the JT effect. (C) 2015 Elsevier B.V. All rights reserved.

The structures of nine iron complexes that show a diversity of experimentally observed spin ground states are optimized and analyzed with Density Functional Theory (DFT). An extensive validation study of the new S12g functional is performed, with the discussion concerning the influence of the environment, geometry and its overall performance based on the comparison with the well proven OPBE functional. The OPBE and S12g functionals give the correct spin ground state for all investigated iron complexes. Since S12g performs remarkably well it can be considered a reliable tool for studying spin state energetics in complicated transition metal systems. [Ministerio de Ciencia e Innovación (MICINN, project CTQ2011-25086/BQU), the Ministerio de Economia y Competitividad (MINECO, project CTQ2014-59212/BQU) and the DIUE of the Generalitat de Catalunya (project 2014SGR1202, and Xarxa de Referència en Química Teòrica i Computacional); MICINN and the FEDER fund (European Fund for Regional Development) under grant UNGI10-4E-801, and the Serbian Ministry of Education and Science (Grant No. 172035). This work was performed in the framework of the COST action CM1305 "Explicit Control Over Spin-states in Technology and Biochemistry (ECOSTBio)" (STSM reference: ECOST-STSM-CM1305-27360).]

The aromatic/antiaromatic behavior of the cyclopentadienyl anion (Cp-), bis(η5-cyclopentadienyl)iron(II) (Fe(Cp)2), as well as of the Jahn-Teller (JT) active cyclopentadienyl radical (Cp∙) and bis(η5-cyclopentadienyl)cobalt(II) (Co(Cp)2) has been investigated using Density Functional Theory (DFT) calculations of the Nuclear Independent Chemical Shifts (NICS). According to the NICS values, pentagon ring in Fe(Cp)2 is more aromatic than isolated Cp-. The NICS parameters have been scanned along the Intrinsic Distortion Path (IDP) for Cp∙ and Co(Cp)2 showing antiaromaticity, which decreases with increasing deviation from high symmetry D5h to low symmetry (LS) C2v. Changes in the NICS values along the IDP revealed that Co(Cp)2 in the LS nuclear arrangement has aromatic character, in contrast to the case of Cp∙ [Projekat Ministarstva nauke Republike Srbije, br. 172035]

The origin for the rotational barrier of organometallic versus inorganic sandwich complexes has remained enigmatic for the past decades. Here, we investigate in detail what causes the substantial barrier for titanodecaphosphacene through spin-state consistent density functional theory. Orbital interactions are shown to be the determining factor. This is the peer-reviewed version of the following article: Vlahovic, F.; Gruden, M.; Swart, M. Rotating Iron and Titanium Sandwich Complexes. Chemistry - A European Journal 2018, 24 (20), 5070–5073. [https://doi.org/10.1002/chem.201704829] Supplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/3005]

A detailed theoretical investigation of cyclophanes with a divergent set of methods ranging from molecular mechanics through semiempirical to ab initio is presented. Cyclophanes have attracted interest over the years due to their unusual chemistry and increasing applications. There has been previous debate over the effects contributing to the greater stability of more-crowded in isomers of certain cyclophanes, and a higher strain in the out isomer was the prevailing explanation. Application of EDA-NOCV and SAPT analysis has enabled us to distinguish between different effects controlling isomer stability and determine the significance of all effects involved. Our results show that, although strain has a large significance, orbital stabilization within the molecule from the aromatic electron density is crucial. Furthermore, we analysed halogen-substituted cyclophanes in order to further understand these subtle effects.

Density functional method with continuum solvation model is used for calculation of partition coefficient logKOW and determination of lipophilicity of 22 most frequently used organophosphate type pesticides. Excellent agreement with experimental data is obtained using three different density functional approximations (one local, one general gradient and one hybrid), and our result highlights DFT as a reliable and trustworthy method for calculation and of lipophilicity for this important class of molecules. Furthermore, calculated lipophilicity results are associated with experimentally determined LD50 and LC50 values, showing that the most toxic pesticides are these with transient characteristics (medium lipophilicity), although this concussion must be taken with a caution due to the many factors influencing the ingestion and action of a certain substance in the body beside lipophilicity. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. OI172035 and Grant no. TR31085]

A detailed theoretical investigation of cyclophanes with a divergent set of methods ranging from molecular mechanics through semiempirical to ab initio is presented. Cyclophanes have attracted interest over the years due to their unusual chemistry and increasing applications. There has been previous debate over the effects contributing to the greater stability of more-crowded in isomers of certain cyclophanes, and a higher strain in the out isomer was the prevailing explanation. Application of EDA-NOCV and SAPT analysis has enabled us to distinguish between different effects controlling isomer stability and determine the significance of all effects involved. Our results show that, although strain has a large significance, orbital stabilization within the molecule from the aromatic electron density is crucial. Furthermore, we analysed halogen-substituted cyclophanes in order to further understand these subtle effects. This is the peer-reviewed version of the following article: Vujovic, M.; Zlatar, M.; Milčić, M. K.; Gruden-Pavlović, M. In/out Isomerism of Cyclophanes: A Theoretical Account of 2,6,15-Trithia-[3(4,10)][7]Metacyclophane and [3(4,10)][7]Metacyclophane as Well as Their Halogen Substituted Analogues. Physical Chemistry Chemical Physics 2017, 19 (14), 9500–9508. [https://doi.org/10.1039/c7cp00557a] Supplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/3024]

Density Functional Tight Binding (DFTB) models are two to three orders of magnitude faster than ab initio and Density Functional Theory (DFT) methods and therefore are particularly attractive in applications to large molecules and condensed phase systems. To establish the applicability of DFTB models to general chemical reactions, we conduct benchmark calculations for barrier heights and reaction energetics of organic molecules using existing databases and several new ones compiled in this study. Structures for the transition states and stable species have been fully optimized at the DFTB level, making it possible to characterize the reliability of DFTB models in a more thorough fashion compared to conducting single point energy calculations as done in previous benchmark studies. The encouraging results for the diverse sets of reactions studied here suggest that DFTB models, especially the most recent third-order version (DFTB3/3OB augmented with dispersion correction), in most cases provide satisfactory description of organic chemical reactions with accuracy almost comparable to popular DFT methods with large basis sets, although larger errors are also seen for certain cases. Therefore, DFTB models can be effective for mechanistic analysis (e.g., transition state search) of large (bio)molecules, especially when coupled with single point energy calculations at higher levels of theory. This is the peer-reviewed version of the following article: Gruden, M., Andjelkovic, L., Jissy, A.K., Stepanović, S., Zlatar, M., Cui, Q., Elstner, M., Journal of Computational Chemistry, 2017, 38 (25), pp. 2171-2185. which has been published in final form at [https://doi.org/10.1002/jcc.24866]. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. [http://cer.ihtm.bg.ac.rs/handle/123456789/2131]

Vibronic coupling theory shows that the cause for spontaneous instability in systems presenting a nondegenerate ground state is the so-called pseudo-Jahn-Teller effect, and thus its study can be extremely helpful to understand the structure of many molecules. While this theory, based on the mixing of the ground and excited states with a distortion, has been long studied, there are two obscure points that we try to clarify in the present work. First, the operators involved in both the vibronic and nonvibronic parts of the force constant take only into account electron nuclear and nuclear nuclear interactions, apparently leaving electron electron repulsions and the electron's kinetic energy out of the chemical picture. Second, a fully quantitative computational appraisal of this effect has been up to now problematic. Here, we present a reformulation of the pseudo-Jahn-Teller theory that explicitly shows the contributions of all operators in the molecular Hamiltonian and allows connecting the results obtained with this model to other chemical theories relating electron distribution and geometry. Moreover, we develop a practical approach based on Hartree-Fock and density functional theory that allows quantification of the pseudo-Jahn-Teller effect. We demonstrate the usefulness of our method studying the pyramidal distortion in ammonia and its absence in borane, revealing the strong importance of the kinetic energy of the electrons in the lowest a(2)'' orbital to trigger this instability. The present tool opens a window for exploring in detail the actual microscopic origin of structural instabilities in molecules and solids. Supplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/3667]

Conspectus The great diversity and richness of transition metal chemistry, such as the features of an open d-shell, opened a way to numerous areas of scientific research and technological applications. Depending on the nature of the metal and its environment, there are often several energetically accessible spin states, and the progress in accurate theoretical treatment of this complicated phenomenon is presented in this Account. The spin state energetics of a transition metal complex can be predicted theoretically on the basis of density functional theory (DFT) or wave function based methodology, where DFT has advantages since it can be applied routinely to medium-to-large-sized molecules and spin-state consistent density functionals are now available. Additional factors such as the effect of the basis set, thermochemical contributions, solvation, relativity, and dispersion, have been investigated by many researchers, but challenges in unambiguous assignment of spin states still remain. The first DFT studies showed intrinsic spin-state preferences of hybrid functionals for high spin and early generalized gradient approximation functionals for low spin. Progress in the development of density functional approximations (DFAs) then led to a class of specially designed DFAs, such as OPBE, SSB-D, and S12g, and brought a very intriguing and fascinating observation that the spin states of transition metals and the SN2 barriers of organic molecules are somehow intimately linked. Among the many noteworthy results that emerged from the search for the appropriate description of the complicated spin state preferences in transition metals, we mainly focused on the examination of the connection between the spin state and the structures or coordination modes of the transition metal complexes. Changes in spin states normally lead only to changes in the metal-ligand bond lengths, but to the best of our knowledge, the dapsox ligand showed the first example of a transition-metal complex where a change in spin state leads also to changes in the coordination, switching between pentagonal-bipyramidal and capped-octahedron. Moreover, we have summarized the results of the thorough study that corrected the experimental assignment of the nature of the recently synthesized Sc3+ adduct of [FeIV(O)(TMC)]2+ (TMC = 1,4,8,11-tetramethylcyclam) and firmly established that the Sc3+-capped iron-oxygen complex corresponds to high-spin FeIII. Last, but not least, we have provided deeper insight and rationalization of the observation that unlike in metalloenzymes, where the FeIV-oxo is usually observed with high spin, biomimetic FeIV-oxo complexes typically have a intermediate spin state. Energy decomposition analyses on the trigonal-bypiramidal (TBP) and octahedral model systems with ammonia ligands have revealed that the interaction energy of the prepared metal ion in the intermediate spin state is much smaller for the TBP structure. This sheds light on the origin of the intermediate spin state of the biomimetic TBP FeIV-oxo complexes The following organizations are thanked for financial support: MINECO (projects CTQ2014-59212-P and CTQ2015-70851-ERC), GenCat (project 2014SGR1202 and XRQTC), EuropeanFund for Regional Development (FEDER, UNGI10-4E-801), and Serbian Ministry of Science

The gold(I)-catalyzed domino-cyclization of 1,6-Diynes with a t-butylcarbonate group in the propargylic position affords α-hydroxycyclohexenones.

A detailed Density Functional Theory (DFT) analysis was performed in order to study the multimode Jahn-Teller (JT) problem in the electronic ground state of manganese phthalocyanine (MnPc). A comparison with the magnesium phthalocyanine ion (MgPc-) and the phthalocyanine trianion (Pc3-), also prone to the JT effect, is presented. Our results clarify the origin and provide the microscopic insight into the symmetry breaking process. The JT distortion is highly influenced by the coordination of phthalocyanine to the Mn-II ion, and occurs over the whole system, while the MgPc- complex ion possesses mainly ligand-based instability. [http://cer.ihtm.bg.ac.rs/handle/123456789/1928] This is peer-reviewed version of the article: [https://dx.doi.org/10.1039/C6CP03859J]

The aim of this work was to determine and understand the origin of the electronic properties of MnIV complexes, especially the zero-field splitting (ZFS), through a combined experimental and theoretical investigation on five well-characterized mononuclear octahedral MnIV compounds, with various coordination spheres (N6, N3O3, N2O4 in both trans (trans-NO) and cis configurations (cis-N2O4) and O4S2). High-frequency and -field EPR (HFEPR) spectroscopy has been applied to determine the ZFS parameters of two of these compounds, MnLtrans‑N2O4 and MnLO4S2. While at X-band EPR, the axial-component of the ZFS tensor, D, was estimated to be +0.47 cm−1 for MnLO4S2, and a D-value of +2.289(5)cm−1 was determined by HFEPR, which is the largest D-magnitude ever measured for a Mn complex. A moderate D value of −0.997(6) cm−1 has been found for MnLtrans‑N2O4. Quantum chemical calculations based on two theoretical frameworks (the Density Functional Theory based on a coupled perturbed approach (CP-DFT) and the hybrid Ligand-Field DFT (LF-DFT)) have been performed to define appropriate methodologies to calculate the ZFS tensor for MnIV centers, to predict the orientation of the magnetic axes with respect to the molecular ones, and to define and quantify the physical origin of the different contributions to the ZFS. Except in the case of MnLtrans‑N2O4, the experimental and calculated D values are in good agreement, and the sign of D is well predicted, LF-DFT being more satisfactory than CP-DFT. The calculations performed on MnLcis‑N2O4 are consistent with the orientation of the principal anisotropic axis determined by single-crystal EPR, validating the calculated ZFS tensor orientation. The different contributions to D were analyzed demonstrating that the d-d transitions mainly govern D in Mn ion. However, a deep analysis evidences that many factors enter into the game, explaining why no obvious magnetostructural correlations can be drawn in this series of MnIV complexes.

1,6-Diynes with a t-butylcarbonate group in the propargylic position undergo gold(I)-catalyzed dominocyclization which affords alpha-hydroxycyclohexenones. The described sequence can be applied on functionalized, highly oxygenated substrates, as examplified in the synthesis of (-)-gabosine H and its epimer. Supplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/3520]

Three new mononuclear manganese(II) complexes, namely [Mn(HL)(2)]center dot 2ClO(4) (1), [Mn(HL)(N(CN)(2)) (H2O)(2)]center dot ClO4 (2) and [Mn(HL)(SCN)(2)] (3) [LH = 4-tert-butyl-2,6-bis-[(2-pyridin-2-yl-ethylimino)-methyl]-phenol], have been synthesized and structurally characterized. An "end-off" compartmental ligand (LH) possesses two symmetrical compartments with N2O binding sites but accommodates only one manganese atom instead of two due to the protonation of the imine nitrogen of one compartment. Although all three complexes are mononuclear, complex 1 is unique as it has a 1 : 2 metal to ligand stoichiometry. The catalytic promiscuity of complexes 1-3 in terms of two different bio-relevant catalytic activities namely catecholase and phenoxazinone synthase has been thoroughly investigated. EPR and cyclic voltametric studies reveal that radical formation rather than metal centered redox participation is responsible for their catecholase-like and phenoxazinone synthase-like catalytic activity. A computational approach suggests that imine bond bound radical generation rather than phenoxo radical formation is most likely responsible for the oxidizing properties of the complexes. Supplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/3657]

In this work, the syntheses and characterization of two novel compounds of adamantane-1-sulfonic acid (1-AdSO(3)H) with cobalt(II) and cadmium(II) are reported. The results of single crystal X-ray analysis of the compounds revealed that adamantane-1-sulfonate (1-AdSO(3)(-)) in the monoanionic form plays different roles in the investigated compounds. Namely, while in compound [Co(H2O)(6)](1-AdSO(3))(2), six water molecules are coordinated to the cobalt(II) ion and 1-AdSO(3)(-) serves as a counter ion, in compound [Cd(H2O)(4)(1-AdSO(3))(2)], two molecules of 1-AdSO(3)(-) are trans-coordinated to the cadmium(II) ion as a monodentate (O)-ligand and the other coordination sites are occupied by water molecules. The obtained compounds showed moderate activity against Artemia salina. U ovom radu prikazana je sinteza i karakterizacija dva nova jedinjenja adamantan-1-sulfonske kiseline (1-AdSO3H) sa kobaltom(II) i kadmijumom(II). Rezultati rend- genske strukturne analize datih jedinjenja ukazuju da monoanjon adamantan-1-sulfonata (1-AdSO3 pokazuje različit afinitet prema Co(II) i Cd(II) jonima). U kompleksu [Co(H2O)6](1-AdSO3)2, šest molekula vode se koordinuje za Co(II) jon, dok 1-AdSO3 ima ulogu kontrajona. U kompleksu [Cd(H2O)4(1-AdSO3)2] dva jona 1-AdSO3 su koordinovana za Cd(II) jon kao monodentati u trans položaju preko kiseonikovih atoma, dok su ostala koordinaciona mesta zauzeta molekulima vode. Dobijena jedinjenja su pokazala umerenu aktivnost na Artemia salina.