Binuclear nickel(<scp>II</scp>) and cobalt(<scp>II</scp>) complexes of the novel binucleating ligand 3,6-bis(1′-pyrazolyl)pyridazine. Crystal and molecular structure and magnetism of bis[µ-3,6-bis(1′-pyrazolyl)pyridazine-N1(Ni1)N2′(Ni1)N2(Ni2)N2″(Ni2)]bis[diaquanickel(<scp>II</scp>)] tetrachloride dihydrate

Rosenberg, Lisa; Thompson, Laurence K.; Gabe, E. J.; Lee, Florence L.

doi:10.1039/dt9860000625

Cited by 33 publications

(2 citation statements)

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“…3.8 Å through the pydz bridge. In fact, an intermediate antiferromagnetic interaction ( J ≈ −71 cm –1 with H = − J S 1 · S 2 ) was found for the singly pydz-bridged copper(II) chain [Cu(μ-pydz)Cl 2 ] n . , This magnetic coupling for the copper(II) complexes is much enhanced in the case of double-bridged pydz or substituted pydz ligands ( J values up to −532 cm –1 ). ,,, Magneto-structural studies on homodinuclear complexes other than copper(II), where the metal ions are bridged by two (M = Ni and Co)/three (M = Mn) substituted pydz ligands, has revealed the occurrence of antiferromagnetic interactions up to −33.6 [Ni(II)], , −11.5 [Co(II)], , and −2.44 cm –1 [Mn(II)] …”

Section: Introductionmentioning

confidence: 99%

From Mononuclear Compounds to [2 × 2] Metallogrids: Ferromagnetically Coupled Systems Built by Nickel(II) and 3,6-Bis(2′-pyridyl)pyridazine (dppn)

Bruno

Marino

Cano³

et al. 2020

Crystal Growth & Design

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Mono-, di-, tri-, and tetranuclear compounds of nickel(II) of formula [Ni(dppn)3](NCS)2·0.5dppn (1), [{Ni(dppn)(NCS)}2(μ-dppn)(μ-NCS)]NCS (2), [Ni3(dppn)2(N3)2(μ-dppn)2(μ-N3)2](ClO4)2·CH3CH2OH·2H2O (3), and [Ni4(μ-dppn)4(μ-N3)4]Cl4·5H2O (4) [dppn = 3,6-bis(2′-pyridyl)pyridazine] have been prepared and their structures determined by single crystal X-ray diffraction. Compound 1 is made up of mononuclear tris-chelated [Ni(dppn)3]2+ units, thiocyanate counterions, and dppn molecules of crystallization. 2 contains cationic dinuclear units, the six coordination around each metal center being achieved with a pyridazine-dppn and one end-on thiocyanate nitrogen as bridges, a didentate dppn ligand and a terminally bound N-thiocyanate. The electroneutrality in 2 is reached by free thiocyanato anions. 3 contains bent trinuclear cationic units where all nickel(II) ions exhibit a NiN6 chromophore with two bridging bis-didentate dppn and two end-on azide groups connecting the metal centers. Didentate dppn and monodentate azide ligands complete the six coordination at the peripheral nickel(II) ions. The charge in 3 is counterbalanced by perchlorate anions and ethanol and water molecules of crystallization are also present. 4 exhibits a [2 × 2] grid-type of nickel(II) ions where each pair of metal atoms are connected across a pyridazine-dppn fragment and one end-on azido group. Free chloride anions neutralize the positive charge of the grid and water molecules of crystallization are also present. Cryomagnetic susceptibility measurements on crushed crystals of 1–4, in the temperature range 1.9–300 K, reveal the occurrence of a Curie law for 1 and overall ferromagnetic behavior for 2–4 [J = +4.52(2) (2), +1.32(1) (3), and +10.50(2) and +9.10(2) cm–1 (4)]. The dominant ferromagnetic contribution across the single end-on thiocyanato (2) or azido bridges (3 and 4) versus the antiferromagnetic one through the pyridazine (2–4) is at the origin of this behavior. The values of the intramolecular ferromagnetic interactions in 3 and 4 were substantiated by DFT-type calculations. No ac signals were observed for 2–4 either in the lack of or under nonzero applied dc fields.

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Section: Introductionmentioning

confidence: 99%

From Mononuclear Compounds to [2 × 2] Metallogrids: Ferromagnetically Coupled Systems Built by Nickel(II) and 3,6-Bis(2′-pyridyl)pyridazine (dppn)

Bruno

Marino

Cano³

et al. 2020

Crystal Growth & Design

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“…Their planarity and limited conformational flexibility disfavor the nonradiative deactivation paths. , From the synthetic point of view, they are also relatively easy to be prepared and modified. Examples of complexes with pyrazolyl–pyridazine ligands coordinated to metals belonging to any of the transition series have been previously described. − Compounds having pyrazolyl or the related triazolyl-pyridazine ligands chelate to Re I (CO) 3 X (X = Cl or Br), ,− and have shown the influence of the presence of substituents in the ligand on the compound properties, i.e., they can modulate their ability for being used as the photocatalyst. , This effect can also be used for the design of efficient light-emitting materials . In the present work, we describe the synthesis, electronic and photophysical properties of a series of monometallic Re I complexes (see Scheme ) based on the pyrazolyl–pyridazine moiety with different substituents to explore the tuning of the photophysical properties and their potential use as ligands with a second metal site.…”

Section: Introductionmentioning

confidence: 99%

Electronic and Photophysical Properties of Re^I(CO)₃Br Complexes Modulated by Pyrazolyl–Pyridazine Ligands

et al. 2019

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The direct reaction of a series of substituted (1H-pyrazol-1yl)pyridazine (L I : 6-(1H-pyrazolyl)pyridazine; L II : 3-chloro-6-(1H-pyrazole-1-yl)-pyridazine; L III : 6-(1H-3,5-dimethylpyrazolyl)pyridazine-3-carboxylic acid; L IV : 3,6-bis-N-pyrazolyl-pyridazine; and L V : 3,6-bis-N-3methylpyrazolyl-pyridazine) with the bromotricarbonyl(tetrahydrofuran)rhenium(I) dimer leads to the monometallic complexes [(L X )Re(CO) 3 Br] (I−V), which displays a nonregular octahedral geometry around the Re I center and a fac-isomerism for the carbonyl groups, whereas pyridazine and pyrazolyl rings remain highly coplanar after coordination to rhenium. Cyclic voltammetry shows one irreversible oxidation and one irreversible reduction for each compound as measured in N,N-dimethylformamide. Oxidation ranges from 0.94 V for III to 1.04 V for I and have been attributed to the Re I /Re II couple. In contrast, the reductions are ligand centered, ranging from −1.64 V for II to −1.90 V for III and V. Density functional theory calculations on the vertical one electron oxidized and one electron reduced species, using the gas-phase optimized geometry for the neutral complex confirm this assignment. Compounds I−V show two absorption bands, one around 410 nm (metal-to-ligand charge transfer (MLCT), Re dπ → π*) and the other at ∼300 nm (intraligand, π → π*). Excitation at 400 nm at 77 K leads to unstructured and monoexponential emission with large Stokes shift, whose maxima vary between 570 (III) and 636 (II) nm. The quantum yields for these emissions in solution are intensified strongly going from air to argon equilibrated solution. Singlet oxygen quantum yields change from 0.03 (III) to 0.21 (IV). These data are consistent with emission from 3 MLCT. The emission undergoes a bathochromic shift when R 1 is a π-donating group (Cl or N-pyrazolyl) and a hypsochromic shift for a π-acceptor (COOH). The bimolecular emission quenching rate constant by triethylamine (TEA) for II, IV, and V is 1.09, 0.745, and 0.583 × 10 8 M −1 s −1 , respectively. Photolysis in dichloromethane−CO 2 saturated solution with TEA as a sacrificial electron donor leads in all cases to formic acid generation.

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Coordination Algorithms Control Molecular Architecture: [Cu^I₄(L2)₄]⁴⁺ Grid Complex Versus [M^II₂(L2)₂X₄]^y+ Side‐By‐Side Complexes (M=Mn, Co, Ni, Zn; X=Solvent or Anion) and [Fe^II(L2)₃][Cl₃Fe^IIIOFe^IIICl₃]

Lan

Kennepohl

Moubaraki

et al. 2003

Chemistry A European J

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The synthesis and characterisation of a pyridazine-containing two-armed grid ligand L2 (prepared from one equivalent of 3,6-diformylpyridazine and two equivalents of p-anisidine) and the resulting transition metal (Zn, Cu, Ni, Co, Fe, Mn) complexes (1-9) are reported. Single-crystal X-ray structure determinations revealed that the copper(I) complex had self-assembled as a [2 x 2] grid, [Cu(I) (4)(L2)(4)][PF(6)](4).(CH(3)CN)(H(2)O)(CH(3)CH(2)OCH(2)CH(3))(0.25) (2.(CH(3)CN)(H(2)O)(CH(3)CH(2)OCH(2)CH(3))(0.25)), whereas the [Zn(2)(L2)(2)(CH(3)CN)(2)(H(2)O)(2)][ClO(4)](4).CH(3)CN (1.CH(3)CN), [Ni(II) (2)(L2)(2)(CH(3)CN)(4)][BF(4)](4).(CH(3)CH(2)OCH(2)CH(3))(0.25) (5 a.(CH(3)CH(2)OCH(2)CH(3))(0.25)) and [Co(II) (2)(L2)(2)(H(2)O)(2)(CH(3)CN)(2)][ClO(4)](4).(H(2)O)(CH(3)CN)(0.5) (6 a.(H(2)O)(CH(3)CN)(0.5)) complexes adopt a side-by-side architecture; iron(II) forms a monometallic cation binding three L2 ligands, [Fe(II)(L2)(3)][Fe(III)Cl(3)OCl(3)Fe(III)].CH(3)CN (7.CH(3)CN). A more soluble salt of the cation of 7, the diamagnetic complex [Fe(II)(L2)(3)][BF(4)](2).2 H(2)O (8), was prepared, as well as two derivatives of 2, [Cu(I) (2)(L2)(2)(NCS)(2)].H(2)O (3) and [Cu(I) (2)(L2)(NCS)(2)] (4). The manganese complex, [Mn(II) (2)(L2)(2)Cl(4)].3 H(2)O (9), was not structurally characterised, but is proposed to adopt a side-by-side architecture. Variable temperature magnetic susceptibility studies yielded small negative J values for the side-by-side complexes: J=-21.6 cm(-1) and g=2.17 for S=1 dinickel(II) complex [Ni(II) (2)(L2)(2)(H(2)O)(4)][BF(4)](4) (5 b) (fraction monomer 0.02); J=-7.6 cm(-1) and g=2.44 for S= 3/2 dicobalt(II) complex [Co(II) (2)(L2)(2)(H(2)O)(4)][ClO(4)](4) (6 b) (fraction monomer 0.02); J=-3.2 cm(-1) and g=1.95 for S= 5/2 dimanganese(II) complex 9 (fraction monomer 0.02). The double salt, mixed valent iron complex 7.H(2)O gave J=-75 cm(-1) and g=1.81 for the S= 5/2 diiron(III) anion (fraction monomer=0.025). These parameters are lower than normal for Fe(III)OFe(III) species because of fitting of superimposed monomer and dimer susceptibilities arising from trace impurities. The iron(II) centre in 7.H(2)O is low spin and hence diamagnetic, a fact confirmed by the preparation and characterisation of the simple diamagnetic iron(II) complex 8. Mössbauer measurements at 77 K confirmed that there are two iron sites in 7.H(2)O, a low-spin iron(II) site and a high-spin diiron(III) site. A full electrochemical investigation was undertaken for complexes 1, 2, 5 b, 6 b and 8 and this showed that multiple redox processes are a feature of all of them.

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Binuclear nickel(II) and cobalt(II) complexes of the novel binucleating ligand 3,6-bis(1′-pyrazolyl)pyridazine. Crystal and molecular structure and magnetism of bis[µ-3,6-bis(1′-pyrazolyl)pyridazine-N¹(Ni¹)N²′(Ni¹)N²(Ni²)N²″(Ni²)]bis[diaquanickel(II)] tetrachloride dihydrate

Abstract: Binuclear Nickel(i1) and Cobalt(i1) Complexes of the Novel Binucleating Ligand 3,6-Bis(l '-pyrazoly1)pyridazine. Crystal and Molecular Structure and Magnetism of Bis[p-3,6-bis(l '-pyrazoIyl)pyridazine-Nl ( Ni1)N2'( Ni1)N2( Ni2)N2"( Ni2)]bis[diaquanickel( II)] Tetrachloride Dihydrate t

Cited by 33 publications

References 11 publications

From Mononuclear Compounds to [2 × 2] Metallogrids: Ferromagnetically Coupled Systems Built by Nickel(II) and 3,6-Bis(2′-pyridyl)pyridazine (dppn)

From Mononuclear Compounds to [2 × 2] Metallogrids: Ferromagnetically Coupled Systems Built by Nickel(II) and 3,6-Bis(2′-pyridyl)pyridazine (dppn)

Electronic and Photophysical Properties of Re^I(CO)₃Br Complexes Modulated by Pyrazolyl–Pyridazine Ligands

Coordination Algorithms Control Molecular Architecture: [Cu^I₄(L2)₄]⁴⁺ Grid Complex Versus [M^II₂(L2)₂X₄]^y+ Side‐By‐Side Complexes (M=Mn, Co, Ni, Zn; X=Solvent or Anion) and [Fe^II(L2)₃][Cl₃Fe^IIIOFe^IIICl₃]

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Binuclear nickel(II) and cobalt(II) complexes of the novel binucleating ligand 3,6-bis(1′-pyrazolyl)pyridazine. Crystal and molecular structure and magnetism of bis[µ-3,6-bis(1′-pyrazolyl)pyridazine-N1(Ni1)N2′(Ni1)N2(Ni2)N2″(Ni2)]bis[diaquanickel(II)] tetrachloride dihydrate

Abstract: Binuclear Nickel(i1) and Cobalt(i1) Complexes of the Novel Binucleating Ligand 3,6-Bis(l '-pyrazoly1)pyridazine. Crystal and Molecular Structure and Magnetism of Bis[p-3,6-bis(l '-pyrazoIyl)pyridazine-Nl ( Ni1)N2'( Ni1)N2( Ni2)N2"( Ni2)]bis[diaquanickel( II)] Tetrachloride Dihydrate t

Cited by 33 publications

References 11 publications

From Mononuclear Compounds to [2 × 2] Metallogrids: Ferromagnetically Coupled Systems Built by Nickel(II) and 3,6-Bis(2′-pyridyl)pyridazine (dppn)

From Mononuclear Compounds to [2 × 2] Metallogrids: Ferromagnetically Coupled Systems Built by Nickel(II) and 3,6-Bis(2′-pyridyl)pyridazine (dppn)

Electronic and Photophysical Properties of ReI(CO)3Br Complexes Modulated by Pyrazolyl–Pyridazine Ligands

Coordination Algorithms Control Molecular Architecture: [CuI4(L2)4]4+ Grid Complex Versus [MII2(L2)2X4]y+ Side‐By‐Side Complexes (M=Mn, Co, Ni, Zn; X=Solvent or Anion) and [FeII(L2)3][Cl3FeIIIOFeIIICl3]

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Binuclear nickel(II) and cobalt(II) complexes of the novel binucleating ligand 3,6-bis(1′-pyrazolyl)pyridazine. Crystal and molecular structure and magnetism of bis[µ-3,6-bis(1′-pyrazolyl)pyridazine-N¹(Ni¹)N²′(Ni¹)N²(Ni²)N²″(Ni²)]bis[diaquanickel(II)] tetrachloride dihydrate

Electronic and Photophysical Properties of Re^I(CO)₃Br Complexes Modulated by Pyrazolyl–Pyridazine Ligands

Coordination Algorithms Control Molecular Architecture: [Cu^I₄(L2)₄]⁴⁺ Grid Complex Versus [M^II₂(L2)₂X₄]^y+ Side‐By‐Side Complexes (M=Mn, Co, Ni, Zn; X=Solvent or Anion) and [Fe^II(L2)₃][Cl₃Fe^IIIOFe^IIICl₃]