Crystal structure, electrochemical and spectroscopic investigation of mer-tris[2-(1H-imidazol-2-yl-κN
 3)pyrimidine-κN
 1]ruthenium(II) bis(hexafluoridophosphate) trihydrate

Bibi, Naheed; Guerra, Renan Barrach; Huamaní, Luis Enrique Santa Cruz; Formiga, André Luiz Barboza

doi:10.1107/s2056989018007995

Cited by 5 publications

(5 citation statements)

References 22 publications

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“…However, perchlorate anions form hydrogen bonds with cations through the NH hydrogen atoms from the imidazole units, giving rise to a network in the crystal. Similar results were observed in the crystal structure of the ruthenium complex with ligand M , recently reported . The absence of direct hydrogen bonding between the complexes may be related to the broad spin transition observed for the sample because the cooperative effects due to intermolecular interactions would be less pronounced in this case .…”

Section: Resultssupporting

confidence: 87%

Switching the Spin-Crossover Phenomenon by Ligand Design on Imidazole–Diazineiron(II) Complexes

et al. 2018

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The iron(II) complexes of two structural isomers of 2-(1H-imidazol-2-yl)diazine reveal how ligand design can be a successful strategy to control the electronic and magnetic properties of complexes by fine-tuning their ligand field. The two isomers only differ in the position of a single diazinic nitrogen atom, having either a pyrazine (Z) or a pyrimidine (M) moiety. However, [Fe(M)3](ClO4)2 is a spin-crossover complex with a spin transition at 241 K, whereas [Fe(Z)3](ClO4)2 has a stable magnetic behavior between 2 and 300 K. This is corroborated by temperature-dependent Mössbauer spectra showing the presence of a quintet and a singlet state in equilibrium. The temperature-dependent single-crystal X-ray diffraction results relate the spin-crossover observed in [Fe(M)3](ClO4)2 to changes in the bond distances and angles of the coordination sphere of iron(II), hinting at a stronger σ donation of ligand Z in comparison to ligand M. The UV/vis spectra of both complexes are solved by means of the multiconfigurational wave-function-based method CASPT2 and confirm their different spin multiplicities at room temperature, as observed in the Mössbauer spectra. Calculations show larger stabilization of the singlet state in [Fe(Z)3]2+ than in [Fe(M)3]2+, stemming from the slightly stronger ligand field of the former (506 cm–1 in the singlet). This relatively weak effect is indeed capable of changing the spin multiplicity of the complexes and causes the appearance of the spin transition in the M complex.

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Section: Resultssupporting

confidence: 87%

Switching the Spin-Crossover Phenomenon by Ligand Design on Imidazole–Diazineiron(II) Complexes

et al. 2018

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“…However, despite the use and overall interest of this molecule in the synthesis of novel compounds, the crystalline structure has not yet been reported, unlike terpyridine and other widely used N-heterocyclic ligands. The data concerning the crystal structure of this molecule and the understanding of the intermolecular force interactions and hydrogen bonds in supramolecular crystal structures are crucial to trace the relationships between structure and properties, and valuable for the rational design of new compounds (Bibi et al, 2018a;Taylor & Sausa, 2018;Bayar et al, 2018;Latosiń ska et al, 2014;Zeman et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Analysis of solvent-accessible voids and proton-coupled electron transfer of 2,6-bis(1H-imidazol-2-yl)pyridine and its hydrochloride

et al. 2019

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The crystal structures of the solid form of solvated 2,6‐bis(1H‐imidazol‐2‐yl)pyridine (H2dimpy) trihydrate, C11H9N5·3H2O·[+solvent], I, and its hydrate hydrochloride salt 2‐[6‐(1H‐imidazol‐2‐yl)pyridin‐2‐yl]‐1H‐imidazol‐3‐ium chloride trihydrate, C11H10N5+·Cl−·3H2O, II, are reported and analysed in detail, along with potentiometric and spectrophotometric titrations for evaluation of the acid–base equilibria and proton‐coupled electron‐transfer reactions. Compound I crystallizes in the high‐symmetry trigonal space group P3221 with an atypical formation of solvent‐accessible voids, as a consequence of the 32 screw axis in the crystallographic c‐axis direction, which are probably occupied by uncharacterized disordered solvent molecules. Additionally, the trihydrated chloride salt crystallizes in the conventional monoclinic space group P21/c without the formation of solvent‐accessible voids. The acid–base equilibria of H2dimpy were studied by potentiometric and spectrophotometric titrations, and the results suggest the formation of H3dimpy+ (pKa1 = 5.40) and H4dimpy2+ (pKa2 = 3.98), with the electrochemical behaviour of these species showing two consecutive irreversible proton‐coupled electron‐transfer reactions. Density functional theory (DFT) calculations corroborate the interpretation of the experimental results and support the assignment of the electrochemical behaviour.

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“…In this case, minor modifications on the heteroaryl moiety led to a spin crossover for the pyrazine complex at 241 K, whereas the pyrimidine complex showed stable magnetic behavior. This strategy of ligand design to fine-tune properties of coordination compounds were widely explored by our group. ,− Moreover, for the heteroaromatic compounds, pyridine (p K a = 5.1) forms a 1:1 asymmetric unit in its protonated form with chloranilic acid, whereas the pyridazine molecule (p K a = 2.3) forms a 2:1 asymmetric unit in its protonated form with that acid . When it comes to more ionizable acids such as pyrimidinium (p K a = 1.3) or pyrazinium (p K a = 0.7), they form 2:1 asymmetric units in their neutral form with the same acid …”

Section: Introductionmentioning

confidence: 99%

Role of Protonation and Isomerism in the Supramolecular Architectures of Heteroaryl-2-imidazole Compounds: Crystal Packing Patterns and Energetics

Huamaní

Tenório

Guerra

et al. 2020

Crystal Growth & Design

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The influence of isomerism and protonation on crystal packing patterns of three isomeric heteroaryl-2-imidazoles and one related compound was investigated by using single-crystal X-ray diffraction and density functional theory. The comparison of their crystal structures helped unveil the details of the energetic balance controlling supramolecular packing and an unprecedented supramolecular synthon. The neutral species were featured by a whole crystal close packing like a herringbone pattern, which was mainly favored by C–H···π interactions. On the other hand, the crystal packing of the protonated species was characterized by π-stacking layers being supported by π···π and anion-π interactions. Energy framework analysis revealed that both Coulombic interactions between hydrogen bond chains and dispersion energies mainly contributed to the stabilization of the herringbone pattern assembly, whereas a predominant contribution from Coulombic energy frameworks to total energy in protonated forms was observed. The different patterns displayed pieces of evidence of not only the important participation of the heteroaryl moieties in the supramolecular assembly but also the significant contribution of protonation hampering the N–H···N hydrogen bonding interactions in the imidazole group. A thorough characterization of the compounds by means of thermogravimetric analysis, differential scanning calorimetry, Fourier-transform infrared spectroscopy, NMR, and electrospray ionization-(+)-MS is also presented.

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Crystal structure, electrochemical and spectroscopic investigation of mer-tris[2-(1H-imidazol-2-yl-κN ³)pyrimidine-κN ¹]ruthenium(II) bis(hexafluoridophosphate) trihydrate

Abstract: The first example of a homoleptic RuII complex with heteroaryl-imidazoles is reported in the meridional stereochemistry, exclusively. The supramolecular hydrogen-bonded network reveals mutual N—H⋯N bonds between adjacent complexes.

Cited by 5 publications

References 22 publications

Switching the Spin-Crossover Phenomenon by Ligand Design on Imidazole–Diazineiron(II) Complexes

Switching the Spin-Crossover Phenomenon by Ligand Design on Imidazole–Diazineiron(II) Complexes

Analysis of solvent-accessible voids and proton-coupled electron transfer of 2,6-bis(1H-imidazol-2-yl)pyridine and its hydrochloride

Role of Protonation and Isomerism in the Supramolecular Architectures of Heteroaryl-2-imidazole Compounds: Crystal Packing Patterns and Energetics

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Crystal structure, electrochemical and spectroscopic investigation of mer-tris[2-(1H-imidazol-2-yl-κN 3)pyrimidine-κN 1]ruthenium(II) bis(hexafluoridophosphate) trihydrate

Abstract: The first example of a homoleptic RuII complex with heteroaryl-imidazoles is reported in the meridional stereochemistry, exclusively. The supra­molecular hydrogen-bonded network reveals mutual N—H⋯N bonds between adjacent complexes.

Cited by 5 publications

References 22 publications

Switching the Spin-Crossover Phenomenon by Ligand Design on Imidazole–Diazineiron(II) Complexes

Switching the Spin-Crossover Phenomenon by Ligand Design on Imidazole–Diazineiron(II) Complexes

Analysis of solvent-accessible voids and proton-coupled electron transfer of 2,6-bis(1H-imidazol-2-yl)pyridine and its hydrochloride

Role of Protonation and Isomerism in the Supramolecular Architectures of Heteroaryl-2-imidazole Compounds: Crystal Packing Patterns and Energetics

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Crystal structure, electrochemical and spectroscopic investigation of mer-tris[2-(1H-imidazol-2-yl-κN ³)pyrimidine-κN ¹]ruthenium(II) bis(hexafluoridophosphate) trihydrate

Abstract: The first example of a homoleptic RuII complex with heteroaryl-imidazoles is reported in the meridional stereochemistry, exclusively. The supramolecular hydrogen-bonded network reveals mutual N—H⋯N bonds between adjacent complexes.