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Plater MJ, Harrison WTA. Sequential Nucleophilic Aromatic Substitution Reactions of Activated Halogens. Int J Mol Sci 2024; 25:8162. [PMID: 39125731 PMCID: PMC11311403 DOI: 10.3390/ijms25158162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2024] [Revised: 07/20/2024] [Accepted: 07/23/2024] [Indexed: 08/12/2024] Open
Abstract
Building blocks have been identified that can be functionalised by sequential nucleophilic aromatic substitution. Some examples are reported that involve the formation of cyclic benzodioxin and phenoxathiine derivatives from 4,5-difluoro-1,2-dinitrobenzene, racemic quinoxaline thioethers, and sulfones from 2,3-dichloroquinoxaline and (2-aminophenylethane)-2,5-dithiophenyl-4-nitrobenzene from 1-(2-aminophenylethane)-2-fluoro-4,5-dinitrobenzene. Four X-ray single-crystal structure determinations are reported, two of which show short intermolecular N-O…N "π hole" contacts.
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Affiliation(s)
- M. John Plater
- Department of Chemistry, University of Aberdeen, Meston Walk, Aberdeen AB24 3UE, UK
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Menéndez-Herrero M, Martín Pendás Á. Persistence of atoms in molecules: there is room beyond electron densities. IUCRJ 2024; 11:210-223. [PMID: 38376913 PMCID: PMC10916289 DOI: 10.1107/s2052252524000915] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Accepted: 01/25/2024] [Indexed: 02/21/2024]
Abstract
Evidence that the electronic structure of atoms persists in molecules to a much greater extent than has been usually admitted is presented. This is achieved by resorting to N-electron real-space descriptors instead of one- or at most two-particle projections like the electron or exchange-correlation densities. Here, the 3N-dimensional maxima of the square of the wavefunction, the so-called Born maxima, are used. Since this technique is relatively unknown to the crystallographic community, a case-based approach is taken, revisiting first the Born maxima of atoms in their ground state and then some of their excited states. It is shown how they survive in molecules and that, beyond any doubt, the distribution of electrons around an atom in a molecule can be recognized as that of its isolated, in many cases excited, counterpart, relating this fact with the concept of energetic promotion. Several other cases that exemplify the applicability of the technique to solve chemical bonding conflicts and to introduce predictability in real-space analyses are also examined.
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Affiliation(s)
| | - Ángel Martín Pendás
- Dpto. Química Física y Analítica, Universidad de Oviedo, 33006 Oviedo, Spain
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Sergeieva T, Demirer TI, Wuttke A, Mata RA, Schäfer A, Linker GJ, Andrada DM. Revisiting the origin of the bending in group 2 metallocenes AeCp 2 (Ae = Be-Ba). Phys Chem Chem Phys 2023. [PMID: 37482883 PMCID: PMC10395002 DOI: 10.1039/d2cp05020j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/25/2023]
Abstract
Metallocenes are well-established compounds in organometallic chemistry, and can exhibit either a coplanar structure or a bent structure according to the nature of the metal center (E) and the cyclopentadienyl ligands (Cp). Herein, we re-examine the chemical bonding to underline the origins of the geometry and stability observed experimentally. To this end, we have analysed a series of group 2 metallocenes [Ae(C5R5)2] (Ae = Be-Ba and R = H, Me, F, Cl, Br, and I) with a combination of computational methods, namely energy decomposition analysis (EDA), polarizability model (PM), and dispersion interaction densities (DIDs). Although the metal-ligand bonding nature is mainly an electrostatic interaction (65-78%), the covalent character is not negligible (33-22%). Notably, the heavier the metal center, the stronger the d-orbital interaction with a 50% contribution to the total covalent interaction. The dispersion interaction between the Cp ligands counts only for 1% of the interaction. Despite that orbital contributions become stronger for heavier metals, they never represent the energy main term. Instead, given the electrostatic nature of the metallocene bonds, we propose a model based on polarizability, which faithfully predicts the bending angle. Although dispersion interactions have a fair contribution to strengthen the bending angle, the polarizability plays a major role.
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Affiliation(s)
- Tetiana Sergeieva
- Department of Chemistry, Saarland University, Campus Saarbrücken, 66123 Saarbrücken, Germany.
| | - T Ilgin Demirer
- Department of Chemistry, Saarland University, Campus Saarbrücken, 66123 Saarbrücken, Germany.
| | - Axel Wuttke
- Institute for Physical Chemistry, Georg-August-University Göttingen, Tammannstrasse 6, D-37077 Göttingen, Germany.
| | - Ricardo A Mata
- Institute for Physical Chemistry, Georg-August-University Göttingen, Tammannstrasse 6, D-37077 Göttingen, Germany.
| | - André Schäfer
- Department of Chemistry, Saarland University, Campus Saarbrücken, 66123 Saarbrücken, Germany.
| | - Gerrit-Jan Linker
- MESA+ Institute for Nanotechnology, University of Twente, 7522 NB Enschede, The Netherlands.
| | - Diego M Andrada
- Department of Chemistry, Saarland University, Campus Saarbrücken, 66123 Saarbrücken, Germany.
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Kaur P, Rajput JK, Singh K, Khullar P, Bakshi MS. Ag and Au Nanoparticles as Color Indicators for Monomer/Micelle-Nanoparticle Interactions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:7802-7814. [PMID: 35710100 DOI: 10.1021/acs.langmuir.2c00853] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Ag and Au nanoparticles (NPs) were used as color indicators to determine the monomer/micelle adsorption on the NP surface. A simple methodology based on the color change of Ag/Au NPs upon interacting with surface-active molecules was developed. A contrasting color change occurred when NPs interact with the monomer/micelle. This was demonstrated by monitoring the adsorption behavior of a series of Gemini surfactants. UV-visible measurements showed a large change in the intensity and wavelength of Ag/Au NP absorbance upon the surface adsorption of the monomer/micelle of Gemini surfactants. The mechanism of surface adsorption and molecular orientation on the solid-liquid interface of NPs was determined by performing the FT-IR and XPS measurements. Results demonstrated that sharp color changes from yellow to red for Ag NPs and red to purple for Au NPs happened when the Gemini surfactant monomer/micelle adsorbs on the NP surface. This colorimeter-based methodology highlighted the applicability of Ag/Au NPs in complex media where such NPs frequently encounter surface-active molecules.
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Affiliation(s)
- Prabhjot Kaur
- Department of Chemistry, Natural and Applied Sciences, University of Wisconsin-Green Bay, 2420 Nicolet Drive, Green Bay, Wisconsin 54311-7001, United States
- Department of Chemistry, B.B.K. D.A.V. College for Women, Amritsar 143005, Punjab, India
- Department of Chemistry, Dr. B.R. Ambedkar National Institute of Technology, Jalandhar 144011, Punjab, India
| | - Jaspreet Kaur Rajput
- Department of Chemistry, Dr. B.R. Ambedkar National Institute of Technology, Jalandhar 144011, Punjab, India
| | - Kultar Singh
- Department of Chemistry, Khalsa College, G. T. Road, Amritsar 143002, Punjab, India
| | - Poonam Khullar
- Department of Chemistry, B.B.K. D.A.V. College for Women, Amritsar 143005, Punjab, India
| | - Mandeep Singh Bakshi
- Department of Chemistry, Natural and Applied Sciences, University of Wisconsin-Green Bay, 2420 Nicolet Drive, Green Bay, Wisconsin 54311-7001, United States
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Unimuke T, Louis H, Eno EA, Agwamba EC, Adeyinka AS. Meta-Hybrid Density Functional Theory Prediction of the Reactivity, Stability, and IGM of Azepane, Oxepane, Thiepane, and Halogenated Cycloheptane. ACS OMEGA 2022; 7:13704-13720. [PMID: 35559178 PMCID: PMC9088921 DOI: 10.1021/acsomega.1c07361] [Citation(s) in RCA: 36] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Accepted: 03/31/2022] [Indexed: 05/09/2023]
Abstract
The application of plain cycloalkanes and heterocyclic derivatives in the synthesis of valuable natural products and pharmacologically active intermediates has increased tremendously in recent times with much attention being paid to the lower cycloalkane members. The structural and molecular properties of higher seven-membered and nonaromatic heterocyclic derivatives are less known despite their stable nature and vast application; thus, an insight into their structural and electronic properties is still needed. Appropriate quantum chemical calculations utilizing the ab initio (MP2) method, meta-hybrid (M06-2X) functional, and long-range-separated functionals (ωB97XD) have been utilized in this work to investigate the structural reactivity, stability, and behavior of substituents on cycloheptane (CHP) and its derivatives: azepane, oxepane, thiepane, fluorocycloheptane (FCHP), bromocycloheptane (BrCHP), and chlorocycloheptane (ClCHP). Molecular global reactivity descriptors such as Fukui function, frontier molecular orbitals (FMOs), and molecular electrostatic potential were computed and compared with lower members. The results of two population methods CHELPG and Atomic Dipole Corrected Hirshfeld Charges (ADCH) were equally compared to scrutinize the charge distribution in the molecules. The susceptibility of intramolecular interactions between the substituents and cycloalkane ring is revealed by natural bond orbital analysis and intramolecular weak interactions by the independent gradient model (IGM). Other properties such as atomic density of states, intrinsic bond strength index (IBSI), and dipole moments are considered. It is acclaimed that the strain effect is a major determinant effect in the energy balance of cyclic molecules; thus, the ring strain energies and validation of spectroscopic specificities with reference to the X-ray crystallographic data are also considered.
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Affiliation(s)
- Tomsmith
O. Unimuke
- Computational
and Bio-Simulation Research Group, University
of Calabar, Calabar 540004, Nigeria
- Department
of Pure and Applied Chemistry, Faculty of Physical Sciences, University of Calabar, Calabar 540004, Nigeria
| | - Hitler Louis
- Computational
and Bio-Simulation Research Group, University
of Calabar, Calabar 540004, Nigeria
- Department
of Pure and Applied Chemistry, Faculty of Physical Sciences, University of Calabar, Calabar 540004, Nigeria
| | - Ededet A. Eno
- Computational
and Bio-Simulation Research Group, University
of Calabar, Calabar 540004, Nigeria
- Department
of Pure and Applied Chemistry, Faculty of Physical Sciences, University of Calabar, Calabar 540004, Nigeria
| | - Ernest C. Agwamba
- Computational
and Bio-Simulation Research Group, University
of Calabar, Calabar 540004, Nigeria
- Department
of Chemical Sciences, Clifford University
Owerrinta, Abia State 440001, Nigeria
| | - Adedapo S. Adeyinka
- Research
Centre for Synthesis and Catalysis, Department of Chemical Sciences, University of Johannesburg, Johannesburg 2006, South Africa
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