scholarly journals Interplay of Halogen and Hydrogen Bonding in a Series of Heteroleptic iron(III) Complexes

2021 ◽  
Author(s):  
Raúl Díaz-Torres ◽  
Jorge Echeverría ◽  
Oliver Loveday ◽  
Phimphaka Harding ◽  
David Harding
Keyword(s):  
Molecular Electrostatic Potential ◽  
Crystal Packing ◽  
Halogen Bonds ◽  
Heteroleptic Complexes ◽  
1D Chain ◽  
Nci Analysis ◽  
Non Covalent Interactions ◽  
Uv Visible ◽  
Hammett Parameter ◽  
Covalent Interactions

<div>The influence of the halogen substituent on crystal packing and redox properties is investigated in a series of heteroleptic complexes [Fe(qsal-X)(dipic)]MeOH (qsal-X = 4-halogen-2-[(8-quinolylimino)methyl]phenolate; dipic = 2,6-pyridinedicarboxylate; X = F 1, Cl 2, Br 3 and I 4).</div><div>Compounds 1 and 2 exhibit triclinic symmetry (P1̅), whereas 3 and 4 crystallise in monoclinic P21/n. The crystal packing shows self-sorting of the ligands with - interactions between the qsal-X ligands and overlap of the dipic ligands to form a 1D chain, that is supported by C-H···O interactions. In 1 and 2, the cross-section of the 1D chain is square, while for 3 and 4, it is rectangular. In the former, the dipic ligands interact through C=O··· interactions, while - interactions are found in 3 and 4. Neighbouring chains are connected via - interactions involving the quinoline rings, but their relative position is driven by the preference of 1 and 2, for C-H···X interactions, whereas 3 and 4 form O···X halogen bonds. The nature and topology of the electron density of these interactions have been investigated using molecular electrostatic potential (MEP) mapping, quantum theory of atoms in molecules (QTAIM) and ‘non-covalent interactions’ (NCI) analysis. UV-Visible experiments show MLCT bands associated with the qsal-X ligands, confirming the structure is stable in solution. Electrochemical studies reveal slight tuning of the Fe3+/Fe2+ redox couple showing a linear relationship between E° and the Hammett parameter σp.</div><div><br></div>

scholarly journals Interplay of Halogen and Hydrogen Bonding in a Series of Heteroleptic iron(III) Complexes

2021 ◽  
Author(s):  
Raúl Díaz-Torres ◽  
Jorge Echeverría ◽  
Oliver Loveday ◽  
Phimphaka Harding ◽  
David Harding
Keyword(s):  
Molecular Electrostatic Potential ◽  
Crystal Packing ◽  
Halogen Bonds ◽  
Heteroleptic Complexes ◽  
1D Chain ◽  
Nci Analysis ◽  
Non Covalent Interactions ◽  
Uv Visible ◽  
Hammett Parameter ◽  
Covalent Interactions

<div>The influence of the halogen substituent on crystal packing and redox properties is investigated in a series of heteroleptic complexes [Fe(qsal-X)(dipic)]MeOH (qsal-X = 4-halogen-2-[(8-quinolylimino)methyl]phenolate; dipic = 2,6-pyridinedicarboxylate; X = F 1, Cl 2, Br 3 and I 4).</div><div>Compounds 1 and 2 exhibit triclinic symmetry (P1̅), whereas 3 and 4 crystallise in monoclinic P21/n. The crystal packing shows self-sorting of the ligands with - interactions between the qsal-X ligands and overlap of the dipic ligands to form a 1D chain, that is supported by C-H···O interactions. In 1 and 2, the cross-section of the 1D chain is square, while for 3 and 4, it is rectangular. In the former, the dipic ligands interact through C=O··· interactions, while - interactions are found in 3 and 4. Neighbouring chains are connected via - interactions involving the quinoline rings, but their relative position is driven by the preference of 1 and 2, for C-H···X interactions, whereas 3 and 4 form O···X halogen bonds. The nature and topology of the electron density of these interactions have been investigated using molecular electrostatic potential (MEP) mapping, quantum theory of atoms in molecules (QTAIM) and ‘non-covalent interactions’ (NCI) analysis. UV-Visible experiments show MLCT bands associated with the qsal-X ligands, confirming the structure is stable in solution. Electrochemical studies reveal slight tuning of the Fe3+/Fe2+ redox couple showing a linear relationship between E° and the Hammett parameter σp.</div><div><br></div>

scholarly journals New approaches to organocatalysis based on C–H and C–X bonding for electrophilic substrate activation

2016 ◽  
Vol 12 ◽  
pp. 2834-2848 ◽  
Author(s):  
Pavel Nagorny ◽  
Zhankui Sun
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Recent Progress ◽  
Halogen Bonds ◽  
Hydrogen Bond Donor ◽  
New Approaches ◽  
Substrate Activation ◽  
Non Covalent Interactions ◽  
Covalent Interactions ◽  
Hydrogen Bond Donors

Hydrogen bond donor catalysis represents a rapidly growing subfield of organocatalysis. While traditional hydrogen bond donors containing N–H and O–H moieties have been effectively used for electrophile activation, activation based on other types of non-covalent interactions is less common. This mini review highlights recent progress in developing and exploring new organic catalysts for electrophile activation through the formation of C–H hydrogen bonds and C–X halogen bonds.

Synthesis, structural properties and reactivity of ruthenocene-based pincer Pd(ii) tetrahydroborate

2019 ◽  
Vol 48 (33) ◽  
pp. 12720-12729 ◽  
Author(s):  
Sergey V. Safronov ◽  
Evgenii I. Gutsul ◽  
Igor E. Golub ◽  
Fedor M. Dolgushin ◽  
Yulia V. Nelubina ◽  
...  
Keyword(s):  
Structural Properties ◽  
Crystal Packing ◽  
Non Covalent Interactions ◽  
Active Intermediates ◽  
Covalent Interactions ◽  
Bonded Complexes

Non-covalent interactions determine the structure, crystal packing and reactivity of isolated ruthenocene-based pincer Pd(ii) complexes. Bifurcate dihydrogen-bonded complexes are active intermediates of tetrahydroborate alcoholysis.

Second-order nonlinear optical properties of eight-membered centrosymmetric cyclic borasiloxanes

2019 ◽  
Vol 43 (27) ◽  
pp. 10948-10958
Author(s):  
Mohan Gopalakrishnan ◽  
Thamodharan Viswanathan ◽  
Ezhumalai David ◽  
Krishnan Thirumoorthy ◽  
Nattamai S. P. Bhuvanesh ◽  
...  
Keyword(s):  
Optical Properties ◽  
Silicon Atom ◽  
Nonlinear Optical ◽  
Crystal Packing ◽  
Second Order ◽  
Nonlinear Optical Properties ◽  
Strong Electron ◽  
Non Covalent Interactions ◽  
Electron Withdrawing Group ◽  
Covalent Interactions

SHG efficiencies of eight-membered centrosymmetric cyclic borasiloxanes arise form distorted silicon atom, strong electron withdrawing group and non-covalent interactions in crystal packing.

scholarly journals A variable-temperature X-ray diffraction and theoretical study of conformational polymorphism in a complex organic molecule (DTC)

RSC Advances ◽  
2018 ◽  
Vol 8 (67) ◽  
pp. 38445-38454 ◽  
Author(s):  
Andrea Gionda ◽  
Giovanni Macetti ◽  
Laura Loconte ◽  
Silvia Rizzato ◽  
Ahmed M. Orlando ◽  
...  
Keyword(s):  
Theoretical Study ◽  
Crystal Packing ◽  
Variable Temperature ◽  
Asymmetric Unit ◽  
X Ray Diffraction ◽  
X Ray ◽  
Complex Organic Molecule ◽  
Non Covalent Interactions ◽  
Complex Organic ◽  
Covalent Interactions

A small conformational change in the asymmetric unit has a significant effect on how non-covalent interactions determine (i) the crystal packing and (ii) the effect of T on the relative balance of electrostatics and dispersion–repulsions.

Solid-State NMR at the University of Ottawa

2015 ◽  
Vol 93 (5) ◽  
pp. 485-491
Author(s):  
David L. Bryce
Keyword(s):  
Solid State ◽  
Solid State Nmr ◽  
Materials Characterization ◽  
Canadian Society ◽  
Halogen Bonds ◽  
Biomolecular Nmr ◽  
Non Covalent Interactions ◽  
Nmr Crystallography ◽  
The University ◽  
Covalent Interactions

This article describes some highlights of the research which has been carried out in my laboratory at the University of Ottawa over the period covering 2005 to 2014. My research is in the general areas of solid-state NMR, applications of quantum chemistry, and biomolecular NMR. The format will follow that of my 2014 Canadian Society for Chemistry Keith Laidler Award presentation given in Vancouver in June 2014 at the 97th Canadian Chemistry Conference and Exhibition. Following a brief introduction, I will present some of our most interesting and exciting recent advances according to the following six themes: 1. Fundamental solid-state NMR. 2. Materials characterization and NMR crystallography. 3. Pharmaceuticals and polymorphism. 4. Non-covalent interactions: Halogen bonds. 5. Biomolecular NMR. 6. Software development.

scholarly journals Decoding conformational polymorphism in organic substances

2014 ◽  
Vol 70 (a1) ◽  
pp. C557-C557
Author(s):  
Ahmed Orlando ◽  
Laura Loconte ◽  
Emanuele Ortoleva ◽  
Carlo Gatti ◽  
Leonardo Lo Presti
Keyword(s):  
Molecular Conformation ◽  
Crystal Packing ◽  
X Ray Diffraction ◽  
Self Recognition ◽  
Crystallization Conditions ◽  
Polymorphic Forms ◽  
Non Covalent Interactions ◽  
Cohesive Energies ◽  
Covalent Interactions

Different polymorphs have different intensive physical properties and it is still impossible to predict from scratch if a change in the crystallization conditions will result in different crystal structures or not. In this contribution, possible correlations are highlighted among charge density features, molecular conformation and interaction energetics in the two known polymorphic forms of (DTC)[1,2], an isothiazole β-sultamic derivative. A tentative rationale is provided for the relative stability of the two forms on the basis of their different self-recognition patterns. Both polymorphs crystallize in the same P21/n space group and show very different non-covalent networks of weak C-H–X (X = N,O,π) interactions due to the dissimilar conformation of the asymmetric units (ASU). Accurate multi-temperature (100 K ≤ T ≤ 298 K) single-crystal X-Ray diffraction experiments were carried out and the evolution of crystal packing and self-recognition energetics were monitored through periodic quantum-mechanical calculations at fixed geometries. Preliminary results show that dispersive/repulsive and electrostatic non-covalent interactions dominate the crystal packing in both polymorphs. At T=100 K the form A have a tighter packing, as it shows a greater propensity in being involved in H bonds than B (see the Hirshfeld surface fingerprint plots[3] of forms A -left- and B -right- here reported). This reflects in greater density, whereas the estimated DFT cohesive energies of the two forms are similar. DTC has enough molecular flexibility to access various favourable arrangements during the nucleation, as the interconversion between the A and B conformers in the gas phase takes place with a very small activation energy. The possible role of the solvent in favouring either of the two observed conformations is discussed.

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