Pyridazine Ligands Research Articles

Tetrakis(pyridazine-κN)bis(selenocyanato-κN)cobalt(II) pyridazine disolvate

Reaction of cobalt(II) nitrate with potassium seleno­cyanate and pyridazine leads to single crystals of the title compound, [Co(NCSe)2(C4H4N2)4]·2C4H4N2, which is isotypic with its nickel(II) thio­cyanate analogue. The Co2+ cations are coordinated by two N-bonded seleno­cyanate ligands and four N atoms from four pyridazine ligands into discrete complexes. The complexes are arranged into layers parallel to (001). These layers are separated by additional non-coordinating pyridazine ligands.

Bis(methanol-1κO)tetra-μ-pyridazine-1:2κ4N:N′;2:3κ4N:N′-di-μ-thiocyanato-1:2κ2N:N;2:3κ2N:N-tetrathiocyanato-1κ2N,3κ2N-trinickel(II) methanol tetrasolvate

Reaction of an excess nickel(II) thio­cyanate with pyridazine leads to single crystals of the title compound, [Ni3(NCS)6(N2C4H4)4(CH3OH)2]·4CH3OH. The crystal structure consists of trimeric discrete complexes, in which two NiII cations are coordinated by two terminal and one μ-1,1 bridging thio­cyanato anions, one methanol mol­ecule and two bridging pyridazine ligands, whereas the central NiII atom is coordinated by two μ-1,1 bridging anions as well as four bridging pyridazine ligands. The asymmetric unit consists of two crystallographically independent Ni cations, one of which is located on a center of inversion, as well as three crystallographically independent thio­cyanato anions, two pyridazine ligands and three independent methanol mol­ecules in general positions. Two of the solvent mol­ecules do not coordinate to the metal atoms and are located in cavities of the structure. The discrete complexes are linked by inter­molecular O—H⋯O and O—H⋯S hydrogen bonding into layers parallel to the bc plane.

Tetrakis(pyridazine-κN)bis(thiocyanato-κN)nickel(II) pyridazine disolvate

The reaction of nickel(II) thio­cyanate with an excess of pyridazine leads to single crystals of the title compound, [Ni(NCS)2(C4H4N2)4]·2C4H4N2. The NiII cations are coordinated by two terminal N-bonded thio­cyanate anions (trans) and four pyridazine ligands in a slightly distorted octa­hedral geometry. The discrete complexes are arranged into layers parallel to the ab plane which are separated by additional non-coordinated pyridazine ligands.

Bis(dicyanamido-κN)tetrakis(pyridazine-κN)nickel(II)

Reaction of nickel(II) chloride with sodium dicyanamide and pyridazine leads to single crystals of the title compound, [Ni{N(CN)2}2(C4H4N2)4], in which the NiII cation is octa­hedrally coordinated by two dicyanamide anions and four pyridazine ligands into a discrete complex that is located on a center of inversion.

Electrochemical, Computational, and Photophysical Characterization of New Luminescent Dirhenium–Pyridazine Complexes Containing Bridging OR or SR Anions

A series of [Re(2)(μ-ER)(2)(CO)(6)(μ-pydz)] complexes have been synthesized (E = S, R = C(6)H(5), 2; E = O, R = C(6)F(5), 3; C(6)H(5), 4; CH(3), and 5; H, 6), starting either from [Re(CO)(5)O(3)SCF(3)] (for 2 and 4), [Re(2)(μ-OR)(3)(CO)(6)](-) (for 3 and 5), or [Re(4)(μ(3)-OH)(4)(CO)(12)] (for 6). Single-crystal diffractometric analysis showed that the two μ-phenolato derivatives (3 and 4) possess an idealized C(2) symmetry, while the μ-benzenethiolato derivative (2) is asymmetrical, because of the different conformation adopted by the phenyl groups. A combined density functional and time-dependent density functional study of the geometry and electronic structure of the complexes showed that the lowest unoccupied molecular orbital (LUMO) and LUMO+1 are the two lowest-lying π* orbitals of pyridazine, whereas the highest occupied molecular orbitals (HOMOs) are mainly constituted by the "t(2g)" set of the Re atoms, with a strong Re-(μ-E) π* character. The absorption spectra have been satisfactorily simulated, by computing the lowest singlet excitation energies. All the complexes exhibit one reversible monoelectronic reduction centered on the pyridazine ligand (ranging from -1.35 V to -1.53 V vs Fc(+)|Fc). The benzenethiolato derivative 2 exhibits one reversible two-electron oxidation (at 0.47 V), whereas the OR derivatives show two close monoelectronic oxidation peaks (ranging from 0.85 V to 1.35 V for the first peak). The thioderivative 2 exhibits a very small electrochemical energy gap (1.9 eV, vs 2.38-2.70 eV for the OR derivatives), and it does not show any photoluminescence. The complexes containing OR ligands show from moderate to poor photoluminescence, in the range of 608-708 nm, with quantum yields decreasing (ranging from 5.5% to 0.07%) and lifetimes decreasing (ranging from 550 ns to 9 ns) (3 > 4 > 6 ≈ 5) with increasing emission wavelength. The best emitting properties, which are closely comparable to those of the dichloro complex (1), are exhibited by the pentafluorophenolato derivative (3).

μ-Halo bridged binuclear ruthenium(III) complexes featuring pyridazine ligands: Synthesis, structure, spectral and electrochemical properties

The reaction of [RuX3(AsPh3)3] and N,N-disubstituted pyridazine-3,6-diamine in benzene under reflux afford novel binuclear, halo-bridged, ruthenium(III) complexes with the general formula [Ru2(AsPh3)2(μ-X)2X4(L)] (X=Cl or Br; L=N,N-disubstituted pyridazine-3,6-diamine). All the complexes have been characterized by elemental analysis, spectral (UV–Vis, EPR) and electrochemical methods (CV, DPV). The electronic spectra of the complexes indicate the presence of d–d and intense LMCT transitions in the visible region. The molecular structure of one of the complexes (2) has been determined by X-ray crystallography, which indicates the bridging coordination of the pyridazine in these binuclear complexes. In complex (2) each metal has a distorted octahedral NCl4As coordination sphere constituted by the two exogenous bridging chlorides. The complexes are paramagnetic (low spin, d5) in nature and all the complexes at 77K show rhombic distortion around the ruthenium ion with three different ‘g’ values (gx≠gy≠gz). All the complexes exhibit two quasi-reversible one electron reductive responses (RuIII–RuIII/RuII–RuIII; RuII–RuIII/RuII–RuII) within the E1/2 range of −0.68 to −0.78V and −1.25 to −1.33V, respectively, versus SCE.

Synthesis and structure of some group VII 1,2-diacyl cyclopentadiene complexes and their pyridazine derivatives

A series of 1,2-diacyl cyclopentadienyl tricarbonyl manganese and rhenium complexes, [M(CO)3{η5-1,2-C5H3(CO-(R)2}] (3a–c and 4a–b), were isolated utilizing a straightforward, 3-step route. The synthetic pathway began with a 1,2-diacyl cyclopentadiene (fulvene), followed by the formation of its corresponding thallium salt and transmetallation with the appropriate pentacarbonyl metal bromide. X-ray crystallographic analysis and high-accuracy mass spectrometry confirmed the structures of the both the 4-methoxyphenyl and 4-chlorophenyl diacyl rhenium complexes, [Re(CO)3{η5-1,2-C5H3(CO-(4-OCH3)C6H4)2}] (4a) and [Re(CO)3{η5-1,2-C5H3(CO-(4-Cl)C6H4)2}] (4b). Diacyl complexes 3a–c and 4a–b were then ring-closed with hydrazine hydrate to form their corresponding pyridazine complexes, [M(CO)3{η5-1,2-C5H3(1,4-(R)2N2C2}] (5a–c and 6a–b), in good yields (60–83%). The pyridazyl ligands were found to be relatively labile, and recrystallization of the target complexes 5a–c and 6a–b afforded only the free pyridazine ligands.

Catena-Poly[[dibromidomercury(II)]-μ-3,6-bis(2-pyridylsulfanyl)pyridazine-κ2N3:N6

In the title coordination polymer, [HgBr2(C14H10N4S2)]n, the HgII atom is four-coordinated in a distorted tetra­hedral geometry by the two N atoms of the pyridyl groups of different 3,6-bis­(2-pyridyl­sulfan­yl)pyridazine ligands and two Br atoms. The bridging function of the cis ligands leads to a helical chain structure along [100].

Pyridazine- versus Pyridine-Based Tridentate Ligands in First-Row Transition Metal Complexes

A series of first-row transition metal complexes with the unsymmetrically disubstituted pyridazine ligand picolinaldehyde (6-chloro-3-pyridazinyl)hydrazone (PIPYH), featuring an easily abstractable proton in the backbone, was prepared. Ligand design was inspired by literature-known picolinaldehyde 2-pyridylhydrazone (PAPYH). Reaction of PIPYH with divalent nickel, copper, and zinc nitrates in ethanol led to complexes of the type [Cu(II)(PIPYH)(NO(3))(2)] (1) or [M(PIPYH)(2)](NO(3))(2) [M = Ni(II) (2) or Zn(II) (3)]. Complex synthesis in the presence of triethylamine yielded fully- or semideprotonated complexes [Cu(II)(PIPY)(NO(3))] (4), [Ni(II)(PIPYH)(PIPY)](NO(3)) (5), and [Zn(II)(PIPY)(2)] (6), respectively. Cobalt(II) nitrate is quantitatively oxidized under the reaction conditions to [Co(III)(PIPY)(2)](NO(3)) (7) in both neutral and basic media. X-ray diffraction analyses reveal a penta- (1) or hexa-coordinated (2, 3, and 7) metal center surrounded by one or two tridentate ligands and, eventually, κ-O,O' nitrate ions. The solid-state stoichiometry was confirmed by electron impact (EI) and electrospray ionization (ESI) mass spectrometry. The diamagnetic complexes 5 and 6 were subjected to (1)H NMR spectroscopy, suggesting that the ligand to metal ratio remains constant in solution. Electronic properties were analyzed by means of cyclic voltammetry and, in case of copper complexes 1 and 4, also by electron paramagnetic resonance (EPR) spectroscopy, showing increased symmetry upon deprotonation for the latter, which is in accordance with the proposed stoichiometry [Cu(II)(PIPY)(NO(3))]. Protic behavior of the nickel complexes 2 and 5 was investigated by UV/vis spectroscopy, revealing high π-backbonding ability of the PIPYH ligand resulting in an unexpected low acidity of the hydrazone proton in nickel complex 2.

Bis(pyridazine-κN)bis(selenocyanato-κN)zinc

The asymmetric unit of the title compound, [Zn(NCSe)2(C4H4N2)2], consists of one ZnII cation, located on a twofold rotation axis, one seleno­cyanate anion and one pyridazine ligand in general positions. The ZnII atom is coordinated by two N-atoms of two pyridazine ligands and two terminal N-bonded seleno­cyanate anions within a slightly distorted tetra­hedral coordination environment. In the crystal, discrete complex mol­ecules are arranged in layers parallel to the ac plane, with ZnII⋯ZnII distances of 8.0906 (6) Å along the a axis and of 9.0490 (7) or 9.3604 (7) Å along the c axis. The complex mol­ecules are further linked via weak Se⋯Se inter­actions, with Se⋯Se distances of 3.8235 (9) Å.

Interesting Copper(I) and Mercury(II) 1D Coordination Polymers Based on 3,6-Bis(2-pyridylthio)pyridazine Ligand: Syntheses, Structures and Properties

Two interesting d10 metal complexes of 3,6-bis(2-pyridylthio)pyridazine ligand (PTP), [Cu3I3(PTP)] n (1) and [HgI2(PTP)] n (2), have been synthesized and characterized by IR, elemental analysis, UV–Vis–NIR spectra, thermal analysis and single crystal X-ray diffraction analysis. Single-crystal X-ray analyses show that two complexes are both 1D chain coordination polymer. Complex 1 is a linear chain structure which is constructed from trinuclear Cu3I3 butterfly-shaped units by means of Cu–I bonds. Complex 2 is one-dimensional helical chain structure. In complex 2, two helical single chains form a double helix structure, and these double helix structures are further assembled to form a quasi 2D network by C–H⋯I hydrogen bonds. Optical diffuse-reflection spectra results suggest complex 1 has the property of the semiconductor.

Self‐Assembly of 3,6‐Bis(4‐triazolyl)pyridazine Ligands with Copper(I) and Silver(I) Ions: Time‐Dependant 2D‐NOESY and Ultracentrifuge Measurements

Two 3,6-bis(R-1H-1,2,3-triazol-4-yl)pyridazines (R = mesityl, monodisperse (CH(2)-CH(2)O)(12)CH(3)) were synthesized by the copper(I)-catalyzed azide-alkyne cycloaddition and self-assembled with tetrakis(acetonitrile)copper(I) hexafluorophosphate and silver(I) hexafluoroantimonate in dichloromethane. The obtained copper(I) complexes were characterized in detail by time-dependent 1D [(1)H, (13)C] and 2D [(1)H-NOESY] NMR spectroscopy, elemental analysis, high-resolution ESI-TOF mass spectrometry, and analytical ultracentrifugation. The latter characterization methods, as well as the comparison to analog 3,6-di(2-pyridyl)pyridazine (dppn) systems and their corresponding copper(I) and silver(I) complexes indicated that the herein described 3,6-bis(1H-1,2,3-triazol-4-yl)pyridazine ligands form [2×2] supramolecular grids. However, in the case of the 3,6-bis(1-mesityl-1H-1,2,3-triazol-4-yl)pyridazine ligand, the resultant red-colored copper(I) complex turned out to be metastable in an acetone solution. This behavior in solution was studied by NMR spectroscopy, and it led to the conclusion that the copper(I) complex transforms irreversibly into at least one different metal complex species.

Dimorphic Modifications of the Thiocyanato‐Bridged Coordination Polymer [Ni(NCS)2(pyridazine)(H2O)0.5]n with Different Magnetic Properties

AbstractReaction of nickel(II) thiocyanate with pyridazine under hydrothermal conditions leads to the formation of the hemihydrate [Ni(NCS)2(pyridazine)(H2O)0.5]n (1I). The crystal structure was determined by X‐ray single‐crystal structure analysis. In the crystal structure two types of NiII cations are found. Both are coordinated by one μ‐1,1‐NCS‐ and two μ‐1,3‐NCS‐bridging thiocyanato anions as well as two μ‐1,2‐bridging pyridazine ligands. The octahedral coordination sphere of Ni1 is completed by one coordinating water molecule and that of Ni2 by one terminal N‐bonded thiocyanato anion. These building blocks are connected into chains, which are further connected into a 2D polymeric network by strong interchain hydrogen bonding. By thermal decomposition of the precursor compound 1I, a new anhydrate [Ni(NCS)2(pyridazine)]n (2) is obtained. On rehydration, this compound transforms into a new polymorphic hemihydrate modification 1II. Magnetic measurements of both forms show completely different behavior: Whereas modification 1I shows a long‐range antiferromagnetic ordering state at TN = 5.4 K, modification 1II only shows Curie–Weiss paramagnetism with weak ferromagnetic interactions.

Synthesis, Crystal Structures, and Thermal Properties of New Zinc(II) Thiocyanato Coordination Compounds

AbstractReaction of zinc(II) thiocyanate with pyrazine, pyrimidine, pyridazine, and pyridine leads to the formation of new zinc(II) thiocyanato coordination compounds. In bis(isothiocyanato‐N)‐bis(μ2‐pyrazine‐N,N) zinc(II) (1) and bis(isothiocyanato‐N)‐bis(μ2‐pyrimidine‐N,N) zinc(II) (2) the zinc atoms are coordinated by four nitrogen atoms of the diazine ligands and two nitrogen atoms of the isothiocyanato anions within slightly distorted octahedra. The zinc atoms are connected by the diazine ligands into layers, which are further linked by weak intermolecular S···S interactions in 1 and by weak intermolecular C–H···S hydrogen bonding in 2. In bis(isothiocyanato‐N)‐bis(pyridazine‐N) (3) discrete complexes are found, in which the zinc atoms are coordinated by two nitrogen atoms of the isothiocyanato ligands and two nitrogen atoms of the pyridazine ligands. The crystal structure of bis(isothiocyanato‐N)‐tetrakis(pyridine‐N) (4) is known and consists of discrete complexes, in which the zinc atoms are octahedrally coordinated by two thiocyanato anions and four pyridine molecules. Investigations using simultaneous differential thermoanalysis and thermogravimetry, X‐ray powder diffraction and IR spectroscopy prove that on heating, the ligand‐rich compounds 1, 2, and 3 decompose without the formation of ligand‐deficient intermediate phases. In contrast, compound 4 looses the pyridine ligands in two different steps, leading to the formation of the literature known ligand‐deficient compound bis(isothiocyanato‐N)‐bis(pyridine‐N) (5) as an intermediate. The crystal structure of compound 5 consists of tetrahedrally coordinated zinc atoms which are surrounded by two isothiocyanato anions and two pyridine ligands. The structures and the thermal reactivity are discussed and compared with this of related transition metal isothiocyanates with pyrazine, pyrimidine, pyridazine, and pyridine.

Catena-Poly[[μ3-hydroxido-tetra-μ2-pyridazine-1:2κ4N:N′;1:3κ2N:N′;2:3κ2N:N′-tetrakis(selenocyanato)-1κN,2κN,3κ2N-trizinc(II)]-μ-cyanido-1:2′κ2C:N

In the crystal structure of the title compound, [Zn3(NCSe)4(OH)(CN)(C4H4N2)4]n one of the two crystallograph­ically independent zinc(II) cations is coordinated by two terminal N-bonded seleno­cyanato anions and two N atoms of two symmetry-related pyridazine ligands in a trigonal-bipyramidal geometry, while the other zinc(II) cation is coordinated by one terminal N-bonded seleno­cyanato anion, one μ-1,2-cyanido anion and three N atoms of three crystallographically independent pyridazine ligands in a slightly distorted octa­hedral coordination geometry. The zinc(II) atoms are further connected via a μ3-hydroxido anion into trinuclear building blocks. The formula unit consists of three zinc cations, four seleno­cyanato anions, one μ3-hydroxido anion, four pyridazine mol­ecules as well as one cyanido anion. The asymmetric unit contains half of a formula unit. One of the zinc atoms, two seleno­cyanato anions, two pyridazine ligands and the μ3-hydroxido anion are located on a crystallographic mirror plane, whereas the cyanido anion is located on a twofold rotation axis. Therefore, this anion is disordered due to symmetry. The cyanido anions connect the metal centres into polymeric zigzag chains propagating along the a axis.

Silver(I) complexes with (1-pyrazolyl)pyridazine ligands: Synthesis, crystal structures and luminescent properties

Four Ag(I) coordination complexes formulated as {[Ag( L 1 )(ClO 4)]} n ( 1), {[Ag( L 1 )(NO 3)]} n ( 2), {[Ag( L 1 )(PF 6)]} 2 ( 3) and {[Ag( L 2 )](ClO 4)·CH 3OH} n ( 4), ( L 1 = 3,6-bis(1-pyrazolyl)pyridazine, L 2 = 3,6-bis(3,5-dimethyl-1-pyrazolyl)pyridazine) have been synthesized in the presence of different anions [ClO 4 − ( 1) and ( 4), NO 3 − ( 2), PF 6 − ( 3)] and structurally characterized by FT-IR spectra, elemental analysis and X-ray diffraction. Studies of X-ray diffraction reveal that complexes 1, 2 and 4 show infinite helical chains, which are the alternate left- and right-handed helical chains. Furthermore, helical chains are arranged to 2D sheet via C–H⋯O (from anion O atoms) hydrogen bonds. As the anion changed to PF 6 −, a dinuclear molecule is formed in complex 3, further constructing a 2D sheets by C–H⋯F hydrogen bonds. The photoluminescence properties of all the complexes 1– 4 have been investigated in the solid state at room temperature.

Pyridazine‐Based Ligands and Their Coordinating Ability towards First‐Row Transition Metals

AbstractTridentate pyridazine ligands with two different substituents at the 3‐ and 6‐positions (pyridyl hydrazone at the 3‐position and tolyl 3tol or tert‐butyl 3tBu at the 6‐position) were prepared in high yields from 3,6‐disubstituted pyridazine hydrazines and pyridine aldehyde by Schiff base condensation. This provides a facile entry into a novel class of heterocyclic molecules exhibiting interesting coordinating abilities. They react with first‐row transition metal nitrates to yield complexes of the type [ML2](NO3)2 (L = 3tol; M = Co 4, M = Ni 5, M = Zn 7) and [ML(NO3)2] (L = 3tol, M = Cu 6; L = 3tBu, M = Ni 8, M = Cu 9, M = Zn 10) as crystalline solids. With the exception of copper compound 6 all complexes employing ligand 3tol form complexes of the ML2 type, whereas with ligand 3tBu exclusively complexes of the ML type are formed, which demonstrates the influence of the substituent at the 6‐position despite its being located far from the coordination site. This points to a pronounced electronic effect. Molecular structures of all complexes were determined by single‐crystal X‐ray diffraction analysis revealing six‐coordinate metal centers in a N6 coordination sphere consisting of two ligands 3 or in a N3O3 sphere with one ligand and two nitrates in the O,‐ and O,O′‐coordination modes, respectively. Diamagnetic zinc complexes 7 and 10 were characterized in solution by 1H NMR spectroscopy. All other complexes are paramagnetic (Evans' method). The redox behavior of all complexes was investigated by cyclic voltammetry, which revealed that the complexes possess the same stoichiometry in solution and in the solid state.

Synthesis and Characterization of Proximal Dinuclear Complexes of Palladium Supported by 2,6-Bis(arylimino)phenoxy (aryl = 2,6-diisopropylphenyl and 2,4,6-tri-tert-butylphenyl) and 3,6-Bis(imino(2,6-diisopropylphenyl))pyridazine Ligands

Two kinds of binucleating ligands, 2,6-bis(arylimino)phenoxy (1a: aryl = 2,6-diisopropylphenyl; 1b: aryl = 2,4,6-tri-tert-butylphenyl) and 3,6-bis(imino(2,6-diisopropylphenyl))pyridazine (2), were prepared, and their proximal complexation with two palladium atoms was studied. Treatment of the sodium compounds of 1a,b with 2 equiv of PdCl2(PhCN)2 and PdMeCl(cod) afforded the corresponding homobimetallic complexes, [2,6-bis(arylimino)phenoxy][RPd(μ-Cl)PdR] (4a: R = Cl, aryl = 2,6-diisopropylphenyl; 4b: R = Cl, aryl = 2,4,6-tri-tert-butylphenyl; 7a: R = Me, aryl = 2,6-diisopropylphenyl; 7b: R = Me, aryl = 2,4,6-tri-tert-butylphenyl), whose structures were characterized spectroscopically and crystallographically. In the reaction between the sodium compound of 1a with 1 equiv of PdCl2(PhCN)2, we detected the NaCl adduct of mononuclear palladium species 5a, which, upon release of NaCl, formed a dimeric complex, ([2,6-bis(2,6-diisopropylphenylimino)phenoxy](PdCl])2 (4a), as confirmed by X-ray analysis. Complexation of 2 with 2 equiv of PdCl2(PhCN)2 and PdMeCl(cod) in the presence of 1 equiv of AgBF4 resulted in the formation of the corresponding cationic complexes ([3,6-bis(imino(2,6-diisopropylphenyl))pyridazine][RPd(μ-Cl)PdR])(BF4) (9a: R = Cl; 9b: R = Me), whose RPd(μ-Cl)PdR skeletons (R = Cl and Me) were revealed spectroscopically and crystallographically.

Solid State Structure of 6,7-Dihydro-1,4-Di(2′-Pyridyl)-5H-Cyclopenta[d]Pyridazine

The X-ray structure of 6,7-dihydro-1,4-di(2′-pyridyl)-5H-cyclopenta[d]pyridazine ligand (5-dppn) shows the existence of a trans/trans conformation. The 5-dppn crystallizes in a triclinic space group P-1 with a = 7.1048(15) A; b = 9.008(2) A; c = 10.986(3) A; α = 88.279(16)°; β = 85.454(15)°; γ = 69.104(12)°; V = 654.7(3) A3 and Z = 2. The analysis of 5-dppn crystal structure demonstrates the presence of edge-edge Ar–H···N and face-face Aliph-H···N centrosymmetric dimer interactions. The unit cell packing arrangement confirmed the presence of two molecules opposite to each other. The X-ray structure of 6,7-dihydro-1,4-di(2′-pyridyl)-5H-cyclopenta[d]pyridazine ligand (5-dppn) shows the existence of a trans/trans conformation.

The effects of auxiliary ligands on the synthesis, crystal structures and properties of three complexes with a substituted pyridazine ligand

Three new complexes, [Co(L)2(SCN)2] (1), [Co2(L)4(μ-N3)2](ClO4)2(H2O)1.5 (2), and [Ni(L)3](ClO4)2(CH3OH)2 (3), have been synthesized and structurally characterized, where L is 3-(3′,5′-dimethyl-pyrazole)-6-Cl-pyridazine. Single crystal X-ray analyses show that all three complexes crystallize in the monoclinic crystal system. In complex (1), the Co(II) atom is in a distorted octahedral environment consisting of four nitrogen atoms from two ligands and two nitrogen atoms of SCN−, which is further extended into a 1D chain by intermolecular hydrogen bonds. Two Co(II) atoms in complex (2) are linked by two azide anions in a μ-1,1 mode to make a binuclear structure. Without any auxiliary ligand, the Ni(II) atom in complex (3) adopts a distorted octahedral geometry involving six nitrogen atoms from three ligands. The electronic absorption spectra of the title compounds are discussed as well. The effects of auxiliary ligands on the structures and properties of the title complexes have been studied and discussed. Three new complexes, [Co(L)2(SCN)2] (1), [Co2(L)4(μ-N3)2](ClO4)(H2O)1.5 (2) and [Ni(L)3](ClO4)2(CH3OH)2 (3), have been synthesized and structurally characterized, where L is 3-(3′,5′-dimethyl-pyrazole)-6-Cl-pyridazine. Complexes (1) and (3) are mononuclear compounds, which are different from the binuclear complex (2). Auxiliary ligands are the main reasons that results in the different structures of the title complexes and their different fungicidal activities.