Diverse topologies of three cobalt(II) coordination polymers constructed from flexible bis(benzimidazole) and dicarboxylate ligands

Three cobalt(II) coordination polymers {[Co(L1)(nda)(H₂O)₂]·2H₂O} _n (1), [Co(L2)(tbi)(H₂O)] _n (2) and [Co(L2)(bpdc)(H₂O)] _n (3) (L1 = 1,3-bis(5,6-dimethylbenzimidazol-1-yl)-2-propanol, L2 = 1,3-bis(benzimidazol-1-yl)-2-propanol, H₂nda = 2,6-naphthalenedicarboxylic acid, H₂tbi = 5-tert-butyl isophthalic acid and H₂bpdc = 4,4′-biphenyldicarboxylic acid) were synthesized and characterized by physicochemical and spectroscopic methods. Complex 1 exhibits a 1D loop-like structure, which is further extended into a 3D 3,3,4T31 network through two O–H···O hydrogen bonding interactions. Complex 2 displays a 1D ladder-like chain, arranged into a 2D supramolecular network with 3,3,4L34 topology via classical O–H···O hydrogen bonding interactions, whereas complex 3 features a 2D 3,4L13 layer structure and further assembles into a 3D framework with a twofold interpenetrating sqc65 topology through O–H···O hydrogen bonding interactions. The fluorescence and catalytic properties of these complexes for the degradation of Congo red in a Fenton-like process have been investigated.     

Syntheses,crystal structures,and properties of three two-dimensional complexes constructed by flexible (2,3-pyridylmethyl)amine

Three two-dimensional coordination polymers [Cd(2,3-Pyma)Cl₂] _n (I), {[Cd(2,3-Pyma)(1,4-Chdc)] · 4H₂O}n (II) and {[Zn₂(2,3-Pyma)(1,2,4,5-Bttc)(H₂O)₄] · 6H₂O} _n (III) (2,3-Pyma = (2,3-pyridylmethyl) amine, H₂-1,4-Chdc = 1,4-cyclohexanedicarboxylic acid, and H₄-1,2,4,5-Bttc = 1,2,4,5-benzenetetracarboxylic acid) have been synthesized and structurally characterized by single crystal X-ray crystallography (CIF files CCDC nos. 989461 (I), 1055685 (II) and 1055686 (III)). Three complexes are all twodimensional layer networks bridged by the flexible 2,3-Pyma ligands or the carboxylate ligands. It is noted that the flexible 1,4-Chdc ligands bind the Cd²⁺ ions into a helical chain structure in complex II. The photoluminescence and thermal properties are investigated.     

Synthesis,characterization, and crystal structures of 2D cobalt(II) and nickel(II) coordination polymers containing flexible bis(benzimidazole) ligands

Three coordination polymers, namely {[Ni(L1)(nip)(H₂O)]·2H₂O} _n (1), [Co(L2)(tbip)] _n (2), and {[Co₂(L3)₂(bptc)]·3H₂O} _n (3) (L1 = 1,4-bis(5,6-dimethylbenzimidazole)butane, L2 = 1,4-bis(5,6-dimethylbenzimidazole)-2-butylene, L3 = 1,3-bis(5,6-dimethylbenzimidazole)propane, H₂nip = 5-nitro-isophthalic acid, H₂tbip = 5-tert-butyl-isophthalic acid, H₄bptc = biphenyl-3,3′,4,4′-tetracarboxylic acid), have been synthesized under hydrothermal conditions and characterized by physicochemical and spectroscopic methods as well as by single-crystal X-ray diffraction analysis. Complexes 1 and 2 both feature a two-dimensional (4,4) layer with (4⁴ × 6²) topology. Complex 3 possesses a uninodal 4-connected 2D htb network. The fluorescence spectra and catalytic properties of the complexes for the degradation of methyl orange by sodium persulfate in a Fenton-like process are reported.     

Hydrostable coordination polymers of a methyl-functionalized 4,4′-bipyridine ligand: structure,stability, magnetic and luminescent properties

The reactions of aromatic dicarboxylic acids and methyl-functionalized 4,4′-bipyridine ligands with metal salts under hydrothermal conditions generated four structurally diverse cobalt(II), zinc(II) and cadmium(II) coordination polymers, [Co(CH₃-BDC)(dmbpy)_0.5] _n (1), [Cd(OH-HBDC)₂(dmbpy)] _n (2), [Zn(NDC)(dmbpy)] _n , (3) and {[Cd(DBA)(dmbpy)_0.5]·2H₂O} _n (4) (CH₃–H₂BDC = 5-methylisophthalic acid, OH–H₂BDC = 5-hydroxyisophthalic acid, H₂NDC = 1,4-naphthalenedicarboxylic acid, H₂DBA = 4,4′-methylenedibenzoic acid, dmbpy = 2,2′-dimethyl-4,4′-bipyridine). All four complexes have been structurally characterized by X-ray crystallography. Complex 1 shows a 3D jsm topology structure with two 1D channels parallel to the a and b axes. Complex 2 has a zigzag chain in which the OH-HBDC ligands point alternately up and down. Complexes 3 and 4 show 2D (4,4) networks when the dinuclear metal centers and their ligands are regarded as nodes and linkers, respectively. Complex 3 also shows twofold interpenetration with 1D channels along the b axis. Two nets of complex 4 interlock in parallel, giving rise to a polycatenated layer (2D → 2D). Thermogravimetric and chemical stabilities, magnetic and luminescent properties of these complexes were investigated.     

Syntheses,Structures, and Properties of Two Zn(II)/Ag(I) Complexes Assembled from Tetracarboxylic Acids and N-Donor Ligands

Two new complexes {[Zn(H₂L)(Bpp)] · H₂O} _n (I) and {[Ag(H₃L)(Bpp)] · 0.25H₂O} _n (II) (H₄L = 5-(2,3-dicarboxy phenoxy) isophthalic acid, Bpp = 1,3-bis(4-pyridyl)propane) were prepared and characterized by single crystal X-ray diffraction (XRD) (CCDC nos. 1578523 (I), 1578529 (II)), element analysis and powder XRD. Compound I showed a one-dimensional chain structure, in which the zinc(II) ion is fourcoordinated with a tetrahedral geometry. Compound II is a 1D chain structure with the H₃L– suspension arms. Complexes I and II are further extended into three-dimensional supramolecular framework via hydrogen bonds and π–π interactions. The solid state luminescent properties of compounds I and II have been investigated.     

Thermal stabilities and crystal structures of two supramolecular microporous frameworks based on carboxylate-dipyridyl mix-ligands

The mix-ligand system of 5-(4-carboxy-2-nitrophenoxy)isophthalic acid (HСn-H₂Ipa) and dipyridyl-type molecule produces two M(II) porous coordination polymers, namely {[Zn(HCn-Ipa)(Dpe)(H₂O)] · 2H₂O} _n (I) and {[Co(Cn-HIpa)(Dpe)(H₂O)₃] · 2.5H₂O} _n (II) (Dpe = 1,2-di(4-pyridyl) ethylene). Structure determinations reveal that two complexes feature different one-dimensional (1D) polymers assembling into supramolecular microporous frameworks with different thermal stabilities. The 3D supramolecular frameworks of complex I show relatively lower stability, which can be caused by relatively larger porous cavity absent of the strong hydrogen bonds interaction, whereas thick-layer blocks in complex II are cohered further together by H-bonding interactions to form its 3D supramolecular network with relatively higher stability, indicating extraordinarily stable H-bonding systems; CIF files CCDC nos. 966919 (I) and 966920 (II).     

Synthesis,crystal structures,luminescence, and photocatalytic properties of two 1D Co(II) coordination polymers constructed with semirigid bis(benzimidazole) and dicarboxylate ligands

Two ternary cobalt(II) coordination polymers (CPs), namely [Co(L1)(npht)] _n (1) and {[Co₂(L2)₂(npht)₂(H₂O)]·H₂O} _n (2) (L1 = 4,4′-bis(benzimidazol-1-ylmethyl)biphenyl, L2 = 1,2-bis(5,6-dimethylbenzimidazol-1-ylmethyl)benzene, and H₂npht = 4-nitrophthalic acid) have been synthesized and structurally characterized by X-ray crystallography. Both CPs feature similar 1D infinite chains containing two distinct loops. CP 1 further forms a 3D supramolecular network via weak C–H···O hydrogen bond interactions. CP 2 shows a 1D two-layer chain structure, assembled through π–π stacking interactions. The electrochemical, luminescence, and photocatalytic activities of the two CPs for the removal of methylene blue under visible or UV light were investigated. Possible photocatalytic mechanisms are discussed.     

A novel bimetallic chain based on [Mo(Cn)<Subscript>8</Subscript>]<Superscript>3−</Superscript> and Eu<Superscript>3+</Superscript> ions as building blocks

A novel Mo^V-Eu^III bimetallic chain, {[Eu^III(Phen)(DMF)₄][Mo^V(CN)₈] · i-C₃H₇OH · 3H₂O} _n (I) (DMF = N,N′-dimethylformamide; Phen = phenanthroline), has been constructed by the reaction of [Mo(CN)₈]^3? with Eu³⁺ and phenanthroline in mixed solvent DMF/i-C₃H₇OH. Complex I is confirmed as a chain structure by X-ray structural analysis. The neighboring chains interact with each other by one type of face-to-face π…π stack with the distance of 3.5522(10) Å. Thus complex I has been extended to a 2D network.     

Synthesis,crystal structures and photocatalytic properties of four silver(I) coordination polymers based on semirigid bis(pyrazole) and carboxylic acid co-ligands

Four Ag(I) coordination polymers, formulated as [Ag(L1)(tpa)_0.5] _n (1), {[Ag(L2)(ndc)_0.5]·0.5H₂ndc} _n (2), [Ag(L3)_0.5(ndc)_0.5] _n (3) and {[Ag(L3)]·H₃bptc} _n (4) (L1 = 4,4′-bis(pyrazole-1-ylmethyl)-biphenyl, L2 = 4,4′-bis(3,5-dimethylpyrazol-1-ylmethyl)-biphenyl, L3 = 1,4-bis(3,5-dimethylpyrazol-1-ylmethyl)benzene, H₂tpa = terephthalic acid, H₂ndc = 2,6-naphthalenedicarboxylic acid, H₄bptc = 3,3′,4,4′-biphenyltetracarboxylic acid), have been hydrothermally synthesized and structurally characterized. Complex 1 features the rare binodal (4,4)-connected 2D 4,4L10 topological network with a point symbol of {3²·4.6²·7}₂{3²·6²·7²}. Complex 2 has a folded ladder-like chain structure, which is further extended into a 3D supramolecular network via O–H···O hydrogen bonding and π···π stacking interactions. Complexes 3 and 4 both possess 1D zigzag chain structures. Complex 3 is further extended into a binodal (3,4)-connected network with the point symbol of {4.8⁴·10}{6²·8²}₂ by Ag···O weak interactions, while complex 4 is further connected through O–H···O hydrogen bonding and π···π interactions to afford a 2D supramolecular structure. The photoluminescence spectra and photocatalytic properties of these complexes for degradation of methylene blue and methyl orange are reported.     

Three cobalt(II) coordination polymers constructed from flexible bis(thiabendazole) and dicarboxylate linkers: crystal structures,fluorescence, and photocatalytic properties

Three Co(II) coordination polymers, namely, {Co(btbb)_0.5(ndc)(H₂O)}_n (1), {[Co(btbb)(bpdc)]·1.5H₂O}_n (2), and {[Co(btbp)₂(3-npa)]·2H₂O}_n (3) (btbb = 1,4-bis(thiabendazole)butane, btbp = 1,3-bis(thiabendazole)propane, H₂ndc = 2,6-naphthalenedicarboxylic acid, H₂bpdc = 4,4′-biphenyldicarboxylic acid and 3-H₂npa = 3-nitro phthalic acid) were synthesized under hydrothermal conditions. Their X-ray crystal structures show that complexes 1 and 2 both have 2D uninodal 3-connected hcb (honeycomb) structures. Complex 1 is further extended into a threefold interpenetrating 3D 4,4-connected mog (moganite) supramolecular architecture with the point symbol of {4.6⁴.8}₂{4².6².8²} by O–H···O hydrogen bonding interactions. Complex 2 shows a 3D supramolecular framework involving π···π stacking interactions. Complex 3 features a uninuclear structure, which is further assembled into an ordered 2D hydrogen-bonded-driven pattern with O–H···O and O–H···N hydrogen bonding interactions. The fluorescence spectra and photocatalytic properties of complexes 1–3 for degradation of methyl orange were investigated.     

Synthesis,spectral and thermal studies on dicarboxylate-bridged palladium(II) coordination polymers. Part II

The synthesis and thermal behavior of the new [Pd(fum)(bipy)] _n ·2nH₂O (1), [Pd(fum)(bpe)] _n ·nH₂O (2) and [Pd(fum)(pz)] _n ·3nH₂O (3) {bipy = 4,4′-bipyridine, bpe = 1,2-bis(4-pyridyl)ethene and pz = pyrazine} fumarate complexes are described in this work as well their characterization by IR and ¹³C CPMAS NMR spectroscopies. TG curves showed that the compounds released organic ligands and lattice water molecules in the temperature range of 46–491 °C. In all the cases, metallic palladium was identified as the final residue.     

Structures and enhanced third-order nonlinear optical performance of four complexes investigated by thin film <Emphasis Type="Italic">Z-</Emphasis>scan technique

Four transition metal complexes have been synthesized via hydrothermal reactions, namely, [Zn(1,3-BIB)(CH₃COO)₂]₂ 1, [Cu₂(1,4-BIB)₃(CO₃)₂](1,4-BIB)·10H₂O 2, {[Mn(H₂O)₂(1,2-BIB)₂]Cl₂}_n 3, and {[Mn(1,2-BIB)(1,4-NDC)]₂}_n 4, where 1,n-BIB = 1,n-bis(imidazol-l-yl-methyl)benzene, n = 2, 3, 4 and 1,4-NDC = naphthalene-1,4-dicarboxylic acid. Complex 1 presents a discrete ring-like structure. Complex 2 shows a ladder-like chain structure, while complex 3 has a joint-like chain structure. Complex 4 features a layer structure constructed from [Mn₂(N₄O₈)] clusters. The third-order nonlinear optical (NLO) properties of these complexes in thin films have been investigated by employing the Z-scan technique. Complexes 1–3 exhibit strong third-order NLO reverse-saturable absorption, while 4 shows third-order NLO saturable absorption and a strong self-defocusing effect. The third-order NLO susceptibilities χ ⁽³⁾ of the four complexes were calculated as 2.74 × 10^?9, 12.24 × 10^?9, 42.78 × 10^?9 and 189.32 × 10^?9 esu, respectively. The electronic structures of the complexes were investigated by density functional theory, and the origins of their NLO properties are discussed.     

Copper oxalate complexes: synthesis and structural characterisation

Six copper(II) oxalate complexes, namely {K₂[Cu(ox)₂]} _n (1), {(Hiz)₂[Cu(ox)₂]} _n (2), {[Cu(ox) (N-Bzliz)₂]} _n (3), (HMeiz)₂[Cu(ox)₂] (4), {[Cu(ox)(Meiz)₂]} _n (5), and [Cu(Hox)₂(H₂O)₂](N-Bzliz) (6) where ox = oxalate ion, iz = imidazole, N-Bzliz = N-benzylimidazole, Meiz = 2-methylimidazole, were synthesised and characterised by single crystal X-ray diffraction (complexes 1–5) or powder X-ray diffraction (compound 6). The three-dimensional crystal packing structures of 2, 4, and 5 are consolidated by intermolecular hydrogen bonds linking the oxygen atom of the oxalate group and the amine or imine group of the imidazole-based part into chains. The molecules of complex 6 are held together by intermolecular hydrogen bonds between the oxygen atoms of the oxalate group and coordinated water molecules.     

Syntheses,Structures, and Magnetic Properties of Two Mn(II) Coordination Polymers Based on 4-Fluorocinnamic Acid and 1,10-Phenanthroline

Two Mn(II) coordination polymers, {[Mn₃ (Pfca)₆(Phen)₂] · 2DMF} _n (I) and [Mn(Pfca)₂(Phen)(H₂O)] _n (II) (HPfca = 4-fluorocinnamic acid, Phen = 1,10-phenanthroline), were synthesized and characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis, and singlecrystal X-ray diffraction (CIF files CCDC nos. 967513 (I), 1542972 (II)). Complex I crystallizes in the triclinic crystal system, space group Pī with a = 11.0821(11), b = 12.2632(12), c = 15.0288(15) Å, α = 87.3760(10)°, β = 88.4610(10)°, γ = 81.2220(10)°, V = 2016.0(3) Å3, ρ_c = 1.369 g/cm³, M _r = 1662.25, Z = 1, F(000) = 853, μ = 0.543 mm^–1, the final R = 0.0592 and wR = 0.1681 for 15498 observed reflections with I > 2σ(I). Complex II is of monoclinic system, space group P2₁/c with a = 18.0539(19), b = 8.5806(9), c = 18.758(2) Å, β = 116.5700(10)°, V = 2599.0(5) ų, ρ_c = 1.491 g/cm³, M _r = 583.44, Z = 4, F(000) = 1196, μ = 0.567 mm^–1, the final R = 0.0337 and wR = 0.0853 for 18139 observed reflections with I > 2σ(I). Complex I features linear Mn(II)-trinuclear units, which form 1D chain structure through F···F weak interactions, and complex II is 1D polymeric Mn(II)-chains. Antiferromagnetic coupling interactions exist within Mn(II)- carboxylate trinuclear in I (J =–0.40 cm^–1) and Mn(II)-carboxylate chain in II (J =–0.45 cm^–1).     

Lanthanide contraction effect on the crystal structures of 2D lanthanide coordination polymers based on 2-(trifluoromethyl)-1<Emphasis Type="Italic">H</Emphasis>-imidazole-4,5-dicarboxylic acid

A series of new two-dimensional (2D) lanthanide(III) coordination polymers, namely {[Ln₂(μ ₂-HTFMIDC)₃(DMA)₄] · 2H₂O} _n [Ln = Pr (1); Nd (2); Sm (3); Eu (4); H₃TFMIDC = 2-(trifluoromethyl)-1H-imidazole-4,5-dicarboxylic acid, DMA = N,N′-dimethylacetamide] for type I and {[Ln₂(μ ₂-HTFMIDC)₃(DMA)₂(H₂O)₂] · DMA} _n [Ln = Eu (5); Gd (6)] for type II, have been successfully prepared under solvothermal conditions and structurally characterized for the first time. Both two types of structures exhibit similar 2D honeycomb-like networks, which are constructed by the linkages of μ ₂-HTFMIDC^2? bis-(bidentate) bridging ligands and Ln(III) metal centers. However, slightly different ABAB stacking fashions of the 2D layers and distinctly different hydrogen bonding interactions between the neighboring 2D layers are observed in crystal structures of type I and type II, which may be attributed to the lanthanide contraction effect. Meanwhile, the solid-state luminescent properties of 4 and 5 have been also investigated.     

Syntheses,crystal structures,and DNA binding and catalytic properties of two transition metal coordination polymers constructed from 5-aminoisophthalic acid and bis-benzimidazole ligands

Two mixed-ligand transition metal coordination polymers, {[Co(aip)(bbp)]·(H₂O)} _n (1) and {[Ni₂(aip)(Hbbop)₂]·(H₂O)₂} _n (2) (H₂aip = 5-aminoisophthalic acid, bbp = 1,3-bis(benzoimidazol-2-yl)propane, H₂bbop = 1,3-bis(benzimidazol-2-yl)-2-oxapropane), were synthesized and characterized by elemental analyses, IR spectra, single-crystal X-ray diffraction, and thermogravimetric analyses. Complex 1 has a 1D chain structure, while 2 has a 3-connected 2D network with (6³) topology. Both structures are further connected by hydrogen bonds and π–π stacking interactions to form the 3D supramolecular architectures. DNA binding and catalytic properties of the two complexes were investigated.     

Crystal structure,spectroscopic and thermal properties of copper(II) and manganese(II) coordination polymers based on triazole-benzoic acid ligands

Two transition metal coordination polymers {[Cu(tba)₂(H₂O)]·2H₂O} _n (1) and {[Mn(Htta)₂(H₂O)₂]·2H₂O} _n (2) {Htba = 3-[1,2,4]triazol-1-yl-benzoic acid, H₂tta = 2-[1,2,4]triazol-1-yl-terephthalic acid} have been synthesized under solvothermal conditions. Both complexes have been characterized by single-crystal X-ray diffraction, X-ray powder diffraction, elemental analysis and FTIR spectroscopy. Complex 1 has a 1-D chain structure in which Cu(II) atoms are doubly bridged by tba^? ligands, which is further stabilized by hydrogen bonding and π–π stacking interactions to give a 3-D supramolecular framework. In complex 2, Mn(II) atoms are doubly bridged by Htta^? ligands to form 1-D chains, which are further connected by intermolecular hydrogen bonds to form a 3-D supramolecular framework. The electronic spectra and thermal behaviors of complexes 1 and 2 are also reported.     

Crystal structure of adducts of copper(II) acetylacetonate and hexafluoroacetylacetonate with 4-aminopyridine

Single crystal X-ray diffraction is used to investigate two synthesized β-diketonate complexes of copper(II) with aminopyridine: Cu(4-NH₂Py)(aa)₂ (I) and Cu(4-NH₂Py)(hfa)₂ (II). The crystals of I and II have a monoclinic system; the unit cell parameters of I are: P2₁/n space group, a = 8.2921(3) Å, b = 14.7243(5) Å, c = 13.4970(4) Å, β = 102.426(1)°, V = 1609.32(9) ų, Z = 4; for II: C2/c space group, a = 23.5704(5) Å, b = 11.4977(2) Å, c = 16.0285(3) Å, β = 109.265(1)°, V = 4100.6(1) ų, Z = 8. The structures of I and II are molecular; they are composed of isolated molecules. The coordination polyhedron of the copper atom is formed by the O atoms of two acetylacetonate ligands (Cu-O 1.940(2)–2.171(2) I and the O atoms of two hexafluoroacetylacetonate ligands (Cu-O 1.940(2)–2.215(3) Å) in II. The molecules of 4-NH₂Py are bonded to the copper atom via the nitrogen atom of the aromatic ring (Cu-N 2.008(2) Å in I and Cu-N 1.978(3) Å in II). Noncoordinated amino groups join the molecules of the complexes together by means of N-H…O hydrogen bonds.     

Syntheses,crystal structures and in vitro anticancer activities of oxovanadium(IV) complexes of amino acid Schiff base and 1,10-phenanthroline ligands

Four oxovanadium(IV) complexes, namely [VO(desa-met)(phen)]·MeOH·2H₂O (1) (desa-met = Schiff base derived from 4-(diethylamino)salicylaldehyde and dl-methionine, phen = 1,10-phenanthroline), [VO(o-van-met) (phen)]·MeOH·CH₂Cl₂·3H₂O (2) (o-van-met = Schiff base derived from o-vanillin and dl-methionine), [VO(dtbs-napa)(phen)]·2H₂O (3) (dtbs-napa = Schiff base derived from 3,5-di-tert-butyl salicylaldehyde and 3-(1-naphthyl)-l-alanine) and [VO(hyna-napa)(phen)]·1.5H₂O (4) (hyna-napa = Schiff base derived from 2-hydroxy-1-naphthaldehyde and 3-(1-naphthyl)-l-alanine), were synthesized and characterized by IR, HRMS, UV–vis spectra, molar conductance and single-crystal X-ray diffraction (XRD). X-ray structural analysis showed that the V(IV) atoms in all four complexes are six-coordinated in a distorted octahedral environment. In the crystals of complexes 1 and 2, π–π stacking interactions together with hydrogen bonds connect the molecular units into 2D networks. Meanwhile, CH–π stacking interactions are observed between the aromatic rings in the crystals of 1 and 4, while the π–π stacking interactions between aromatic rings in the crystals of 2 and 3 are arranged with a face-to-face mode. The in vitro anticancer activities of these complexes against A-549 and HeGp2 cells were tested by MTT assay.     

A series of 3d metal complexes prepared by in situ reactions of a flexible diacylhydrazine ligand: synthesis,structures and magnetic properties

The coordination reactions of 3d metal salts with malonic acid N,N′-bis(salicyloyl) bishydrazide (H₆mbshz) afforded three complexes, namely [Cu₂(H₂bshz)(Py)₄Cl₂]·Py (1) (Py = pyridine), [Fe₂(bshz)(Py)₂] (2) and the known complex [Ni₄(aehba)₂(DMF)₂(H₂O)₂]·2DMF (3), where bshz = N,N′-bis(salicyloyl)hydrazine anion and aehba^4? = azo-enolic-2-hydroxybenzamide anion. The X-ray crystal structures of all three complexes have been obtained. Complexes 1 and 2 are composed of N–N-bridged binuclear units, while complex 3 displays a planar tetranuclear structure in which four Ni(II) centers are linked together by N–N and N=N bonds. The bshz anions in 1 and 2 and aehba^4? anions in 3 were all generated in situ from H₆mbshz. A mechanism for these reactions is proposed, involving tandem C–N cleavage and C–N/N–N coupling processes via free radical intermediates. Magnetic investigations revealed dominant antiferromagnetic interactions between the metallic centers of each complex.