Iron(III) induced 2-phenyl imidazolidine ring hydrolysis of a new binucleating Schiff base ligand: X-ray structure of the mononuclear Fe(NNO)2 end product

The reaction of triethylenetetramine, salicylaldehyde and benzaldehyde in 1:2:1 mole ratio in methanol at room temperature affords a novel μ-bis(tridentate) ligand H₂L′ through the formation of an imidazolidine ring within the parent hexadentate precursor in a two step reaction. The ligand H₂L′ reacts with Fe(ClO₄)₂ · 6H₂O in aqueous methanol in the presence of triethylamine to form the mononuclear [Fe^IIIL](ClO₄) complex, (where L²⁻ is the anion of the parent hexadentate H₂saltrien ligand) after the cleavage of the imidazolidine ring. The mononuclear complex has a structure with an N₄O₂ donor atom set of the hexadentate ligand forming a distorted octahedral coordination geometry around the metal atom as established from a crystal structure determination. The Fe-N(imine) distances are 1.934(10) and 1.948(9) Å, Fe-N(amine) distances are 2.062(8) and 2.076(9) Å and Fe-O(phenol) distances are 1.864(8) and 1.872(7) Å. The terminal oxygen donor atoms occupy cis positions and the remaining four nitrogen atoms (two cis amine and two trans imine) complete the coordination sphere. The mononuclear complex has a magnetic moment 1.89 μ_B corresponding to the low-spin 3d⁵ configuration. The UV-Vis spectrum of the end product, after the imidazolidine ring hydrolysis, is different from the spectrum of the initial reaction mixture containing the μ-bis(tridentate) ligand H₂L′.     

Manganese(III) complexes of N2O2 donor 5-bromosalicylideneimine ligands: Combined effects of electron withdrawing substituents and chelate ring size variations on electrochemical properties

A series of mononuclear manganese(III) complexes of formulae [Mn(L)(X)(H₂O)] (1-13) and [Mn(L)(X)] (14-17) (X = ClO₄, F, Cl, Br, I, NCS, N₃), derived from the Schiff bases of 5-bromosalicylaldehyde and different types of diamine (1,2-diaminoethane, 1,2-diaminopropane, 1,3-diaminopropane and 1,4-diaminobutane), have been synthesized and characterized by the combination of IR, UV-Vis spectroscopies, cyclic voltammetry and by X-ray crystallography. The redox properties of all the manganese(III) complexes show grossly identical features consisting of a reversible or quasireversible Mn^III/Mn^II reduction. Besides Mn^III/Mn^II reduction, the complexes 4, 5, 10, 13 and 16 also show reversible or quasireversible Mn^III/Mn^IV oxidation. A linear correlation has been found for the complexes 5, 7, 11 and 13 [Mn(L²)(X)(H₂O)] (X = F, Cl, Br, I) when E_1/2 [Mn^III/Mn^II] is plotted against Mulliken electronegativities (χ_M). The effect of the flexibility of the ligand on redox potential has been studied. It has been observed that the manganese(II) state is stabilized with increasing flexibility of the ligand environment. The crystal structure of 6 shows an octahedral geometry.     

Reactivity of a cobalt(III)-peroxo complex in oxidative nucleophilic reactions

A mononuclear cobalt(III)-peroxo complex bearing a macrocyclic tetradentate N₄ ligand, [Co^III(TMC)(O₂)]⁺ (TMC = 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane), was generated in the reaction of [Co^II(TMC)]²⁺ and H₂O₂ in the presence of triethylamine in CH₃CN. The reactivity of the cobalt(III)-peroxo complex was investigated in aldehyde deformylation with various aldehydes and compared with that of iron(III)- and manganese(III)-peroxo complexes, such as [Fe^III(TMC)(O₂)]⁺ and [Mn^III(TMC)(O₂)]⁺. In this reactivity comparison, the reactivities of metal-peroxo species were found to be in the order of [Mn^III(TMC)(O₂)]⁺ > [Co^III(TMC)(O₂)]⁺ > [Fe^III(TMC)(O₂)]⁺. A positive Hammett ρ value of 1.8, obtained in the reactions of [Co^III(TMC)(O₂)]⁺ and para-substituted benzaldehydes, demonstrates that the aldehyde deformylation by the cobalt(III)-peroxo species occurs via a nucleophilic reaction.     

A dimeric polyoxometalate sandwich motif containing a truncated {Mn3O4} cubane core

A novel sandwich-type silicotungstate motif, K₁₈[Mn^II₂{Mn^II(H₂O)₅Mn^III₃(H₂O)(B-β-SiW₉O₃₄)(B-β-SiW₆O₂₆)}₂]·20H₂O 1, has been isolated from the reaction of K₈[γ-SiW₁₀O₃₆]·12H₂O and manganese ions in aqueous acidic media. The transition metal-substituted polyoxometalate (TMSP) 1 has been fully characterized by single-crystal X-ray diffraction, elemental analysis, thermogravimetric analysis, and infrared spectroscopy. This dimeric polyanion consists structurally of the sandwich polyanion {Mn^II(H₂O)₅Mn^III₃(H₂O)(B-β-SiW₉O₃₄)(B-β-SiW₆O₂₆)}, dimerized via two manganese(II) linker ions. Each monomeric unit is composed of two non-equivalent Keggin fragments, (B-β-SiW₈O₃₁) and (B-β-SiW₆O₂₆), linked to each other via three manganese ions resulting in a truncated {Mn₃O₄} cubane core. Experimental, structural, and electrochemical aspects of the material are reported and discussed.     

Ligand-to-ligand electron transfer and temperature induced valence tautomerism in o-dioxolene chelated manganese complexes

Three polymeric o-dioxolene chelated manganese(III) complexes, {[Mn^III(H₂L¹)(Cl₄Cat)₂][Mn^III(Cl₄Cat)₂(H₂O)₂]}_∞ (1) (L¹ = N,N′-bis(2-pyridylmethyl)-1,4-butanediamine, Cl₄Cat = tetrachlorocatecholate dianion], {[Mn^III(H₂L¹)(Br₄Cat)₂][Mn^III(Br₄Cat)₂(H₂O)₂]·4DMF}_∞, (2) and {[Mn^III(H₂L²)(Br₄Cat)₂][Mn^III(Br₄Cat)₂(DMF)₂]}_∞ (3) (L² = N,N′-bis(2-pyridylmethyl)-1,6-hexanediamine, Br₄Cat = tetrabromocatecholate dianion) have been synthesized and structures were determined by X-ray crystallography. All the complexes were fully characterized by various spectroscopic techniques and their electronic properties are described. It was found that the simple protonation or deprotonation of the bridging ligand (L¹ or L²) coordinated to metal-dioxolene chromophore induce a change in the oxidation state of the coordinated dioxolene ligand without affecting the metal oxidation state. As a result, drastic change in the optical absorption properties of the complexes is observed in the visible and near-IR region as the transformation involves semiquinone-catecholate ligands. Moreover, all three complexes undergo thermally induced valence tautomerism in solution. For all the complexes, on increasing the temperature, the intensity of the lower energy Inter Valence Charge Transfer (IVCT) band at about 1930 nm increases with corresponding decrease of 600 nm band with an isosbestic point at 1820 nm due to the formation of mixed valence species Mn^II(X₄SQ)(X₄Cat)⁻ from (X = Cl or Br) by the transfer of one electron from Cat²⁻ to Mn^III center.     

Saccharose complexes of manganese in different oxidation states

The interaction between saccharose and manganese in different oxidation states was studied in alkaline media by polarographic, potentiometric, ESR spectroscopic and UV-Vis spectrophotometric methods. The results showed that stable manganese(II) and manganese(III) complexes and a complex of manganese(II,III) in a mixed oxidation state were formed with the composition [Mn^IIL(OH)₂], [Mn₂^IIIL₂(OH)₈]²⁻ and [Mn^IIMn^IIIL₂(OH)₆]⁻, respectively. The manganese(II)-saccharose complex was shown to dimerize in alkaline media. The stability constants of the Mn(II,III) and Mn(III) complexes were determined. The oxidation of the manganese(II)-saccharose complex by a stoichiometric amount of K₃ [FeCN]₆ resulted in the formation of the manganese(III) and manganese(IV) complexes. However, oxidation by molecular oxygen only yielded the manganese(III) complex which reduced spontaneously in inert atmosphere to the mixed valence Mn(II,III) complex. The latter was able to be oxidized again by oxygen to the Mn(III) complex. This process proved to be reversible and could be repeated several times.     

A deliberate synthesis of a mononuclear trans-dimethoxide complex of ruthenium(III). X-ray crystal structure, electrochemistry and electron paramagnetic resonance

Using bis(3,5-dimethylpyrazol-1-yl)methane as the bidentate N donor ligand L, the yellow compound trans-[Ru^IIIL₂(OMe)₂]ClO₄ · CH₂Cl₂ is synthesized. It is a rare example of a mononuclear dialkoxo complex of Ru(III). It shows a quasireversible Ru(II/III) couple at −0.65 V versus NHE in acetonitrile at a Pt electrode. Its magnetic moment at room temperature corresponds to one unpaired electron. It displays a rhombic EPR spectrum in acetone at 77 K with g = 2.219, 2.062 and 1.855.     

trans-[Ru(N-N)2Cl2] species, where N-N is bis(3,5-dimethylpyrazol-1-yl)methane

Using bis(3,5-dimethylpyrazol-1-yl)methane as an N-N donor ligand, a trans-[Ru^III(N-N)₂Cl₂]⁺ core has been isolated from the direct reaction of the ligand with RuCl₃ · xH₂O and characterized structurally for the first time. The core displays a rhombic EPR spectrum and a quasireversible Ru(II/III) couple with an E_1/2 of −0.34 V versus NHE.     

Synthesis, characterization, electrochemical and magnetic studies on manganese(III) complexes involving bridging carboxylates

A series of carboxylate-bridged manganese(III) complexes derived from Schiff bases obtained by the condensation of salicylaldehyde or 5-bromo-salicylaldehyde and different types of diamine have been synthesized and characterized and, in the case of [Mn₂(L1)₂(μ-ClCH₂COO)](ClO₄) (1), the structure has been obtained by X-ray crystallography. The structure of 1 consists of two manganese atoms separated by 5.487(3) Å and bridged by a carboxylate anion. This dinuclear structural unit is linked by bridging phenoxy oxygens to adjacent dinuclear units to produce a one-dimensional chain. Cyclic voltammograms of all the compounds exhibit grossly similar features consisting of a reversible or quasi-reversible Mn^III/Mn^II reduction and a Mn^III/Mn^IV oxidation. It has been observed that bromo-substitution stabilizes the lower oxidation state in the Mn^III/Mn^II couple and destabilizes the higher oxidation state in the Mn^III/Mn^IV couple. Variable temperature magnetic susceptibility measurements of 1 show a weak antiferromagnetic interaction. The magnetic behavior is satisfactorily modeled by inclusion of zero-field splitting and an intermolecular interaction component.     

Synthesis and characterization of mixed-ligand ruthenium(III) complexes with oxalate and acetylacetonate ions

Two mononuclear mixed-ligand ruthenium(III) complexes with oxalate dianion (ox²⁻) and acetylacetonate ion (2,4-pentanedionate, acac⁻), K₂[Ru(ox)₂(acac)] (1) and K[Ru(ox)(acac)₂] (2), were prepared as a candidate for a building block. In fact, reaction of complex 2 with manganese(II) sulfate gave a heterometallic tetranuclear complex, TBA[Mn^II{(μ-ox)Ru^III(acac)₂}₃] (5) in the presence of tetrabutylammonium (TBA) bromide. The ¹H NMR, UV-Vis, selected IR and FAB mass spectral data of these complexes are presented. Both mixed-ligand ruthenium(III) complexes gave a Nernstian one-electron reduction step in 0.1 mol dm⁻³ Na₂SO₄ aqueous solution on a mercury electrode at 25 °C. Comparison of observed reversible half-wave potentials with calculated values for a series of [Ru(ox)_n(acac)_3 − n]ⁿ⁻ (n=0-3) complexes by using Lever’s ligand electrochemical parameters is presented.     

Genetic Characterization and Role in Virulence of the Ribonucleotide Reductases of Streptococcus sanguinis

Streptococcus sanguinis is a cause of infective endocarditis and has been shown to require a manganese transporter called SsaB for virulence and O₂ tolerance. Like certain other pathogens, S. sanguinis possesses aerobic class Ib (NrdEF) and anaerobic class III (NrdDG) ribonucleotide reductases (RNRs) that perform the essential function of reducing ribonucleotides to deoxyribonucleotides. The accompanying paper (Makhlynets, O., Boal, A. K., Rhodes, D. V., Kitten, T., Rosenzweig, A. C., and Stubbe, J. (2014) J. Biol. Chem. 289, 6259–6272) indicates that in the presence of O₂, the S. sanguinis class Ib RNR self-assembles an essential diferric-tyrosyl radical (Fe^III₂-Y^•) in vitro, whereas assembly of a dimanganese-tyrosyl radical (Mn^III₂-Y^•) cofactor requires NrdI, and Mn^III₂-Y^• is more active than Fe^III₂-Y^• with the endogenous reducing system of NrdH and thioredoxin reductase (TrxR1). In this study, we have shown that deletion of either nrdHEKF or nrdI completely abolishes virulence in an animal model of endocarditis, whereas nrdD mutation has no effect. The nrdHEKF, nrdI, and trxR1 mutants fail to grow aerobically, whereas anaerobic growth requires nrdD. The nrdJ gene encoding an O₂-independent adenosylcobalamin-cofactored RNR was introduced into the nrdHEKF, nrdI, and trxR1 mutants. Growth of the nrdHEKF and nrdI mutants in the presence of O₂ was partially restored. The combined results suggest that Mn^III₂-Y^•-cofactored NrdF is required for growth under aerobic conditions and in animals. This could explain in part why manganese is necessary for virulence and O₂ tolerance in many bacterial pathogens possessing a class Ib RNR and suggests NrdF and NrdI may serve as promising new antimicrobial targets.     

A new mixed-valence hexanuclear cobalt complex, [Co4Co2(dea)2(Hdea)4)(piv)4](ClO4)2·H2O: Synthesis, crystal structure and magnetic properties

A new Co^II/Co^III hexanuclear complex, [Co₄^IICo₂^III(dea)₂(Hdea)₄)(piv)₄](ClO₄)₂·H₂O 1, has been obtained by reacting cobalt(II) perchlorate, diethanolamine, and pivalic acid (H₂dea = diethanolamine and piv = pivalato anion). The cobalt ions are held together by four μ₃ and four μ₂ alkoxo bridges as well as by four syn-syn carboxylato groups. The hexanuclear motif contains four Co(II) and two Co(III) ions. The {Co^II₄Co^III₂(μ₂-O)₄(μ₃-O)₄} core can be described as a four face-sharing monovacant and bivacant distorted heterocubane units. The cobalt(III) ions are hexacoordinated. Two of the cobalt(II) are hexacoordinated, while the two others are pentacoordinated with a bipyramidal stereochemistry. The magnetic properties of 1 have been investigated in the temperature range 1.9-300 K. Compound 1 exhibits an overall antiferromagnetic behaviour with a ground singlet spin state.     

Synthesis, characterization, electrochemical and spectroscopic investigation of cobalt(III) Schiff base complexes with axial amine ligands: The layered crystal structure of [Co(salophen)(4-picoline)2]ClO4 · CH2Cl2

Cobalt(III) complexes with potentially tetradentate salophen (H₂salophen = N,N′-bis(salicylidene)-1,2-phenylenediamine) as equatorial ligand and with different axial amine ligands (NH₃, cyclohexylamine, aniline, 4-picoline and pyridine) were synthesized and characterized by IR, ¹H NMR, elemental analysis. Electronic spectra and electrochemical properties of the complexes were studied in DMF solutions. The lowest energy transitions, which occur between 464.8 and 477 nm, are attributed mainly to the intraligand charge transfer, confirmed by Zindo/S electronic structure calculations. The reduction potentials of Co(III)/Co(II) are more affected than those of Co(II)/Co(I) by the axial amine ligands. The crystal structure of the [Co^III(salophen)(4- picoline)₂]ClO₄ · CH₂Cl₂ was determined, indicating that the cobalt(III) center is six coordinated surrounded by the tetradentate salophen ligand and two 4-picoline ligands. The crystal packing of the complex shows a layered structure, in which the perchlorate counter ions and also the lattice solvent molecules are intercalated between the bc planes of the complex cations.     

Cobalt(III) complexes with linear hexadentate N6 or N4S2 donor set atoms providing pyridyl-amide-amine/thioether coordination

Two new cobalt(III) complexes of symmetric hexadentate ligand with N₆ [1,10-bis(2-picolinamide)-4,7-diazadecane (pycdpnen)] and N₄S₂ [1,8-bis(2-picolinamide)-3,6-dithiaoctane (pycdadt)] donor set atoms have been synthesized as perchlorate salts and characterized by spectroscopic methods. All two ligands with strong-field pyridylcarboxamido N donor stabilize Co(III) as demonstrated by the facile oxidation of the cobalt center. The structures of [Co(pycdpnenH₋₂)](ClO₄) (1) and [Co(pycdadtH₋₂)](ClO₄) · H₂O (2) investigated by COSY, HMBC, HMQC and NOESY NMR studies show that compounds 1 and 2 have the same geometrical configuration. The X-ray analysis reveals that complex 2 crystallizes in a orthorhombic space group Pccn. The cation [Co(pycdadtH₋₂)]⁺ is distorted octahedral with the two pyridyl groups in cis position.     

Binuclear manganese(III) complexes of an unsymmetric pyrazolate-based compartmental ligand with hard donor set

The synthesis, crystal structure and magnetic properties of manganese(III) binuclear complexes [Mn^III₂(L-3Н)₂(CH₃ОH)₄]·2CH₃ОH (1) and [Mn^III₂(L-3Н)₂(Py)₄]·2Py (2) (L = 3-[(1E)-N-hydroxyethanimidoyl]-4-methyl-1H-pyrazole-5-carboxylic acid) are reported. The ligand contains two distinct donor compartments formed by the pyrazolate-N and the oxime or the carboxylic groups. The complexes were characterized by X-ray single crystal diffraction, revealing that both 1 and 2 consist of dinuclear units in which the two metal ions are linked by double pyrazolate bridges with a planar {Mn₂N₄} core. Cryomagnetic measurements show antiferromagnetic interaction with g = 1.99, J = −3.6 cm⁻¹, Θ = −2.02 K for 1 and g = 2.00, J = −3.7 cm⁻¹, Θ = 1.43 K for 2.     

The effects of point of substitution on the electrochemical behavior of new manganese phthalocyanines, tetra-substituted with diethylaminoethanethiol

The syntheses and comparative studies of the spectral, voltammetry and spectroelectrochemical properties of new manganese phthalocyanine complexes, tetra-substituted with diethylaminoethanethio at the peripheral (complex 3a) and non-peripheral positions (complex 3b) are reported. Solution electrochemistry of complex 3a showed quasi-reversible metal-based (Mn^IIIPc⁻²/Mn^IIPc⁻², E_1/2 = −0.07 V vs. Ag|AgCl) and ring-based (Mn^IIPc⁻²/Mn^IIPc⁻³, E_1/2 = −0.78 V vs. Ag|AgCl) reductions, but no ring-based oxidation. However, complex 3b showed weak irreversible ring-oxidation signal (E_p = +0.86 vs. Ag|AgCl). Reversible metal-based (Mn^IIIPc⁻²/Mn^IIPc⁻², E_1/2 = −0.04 V vs. Ag|AgCl) and ring-based (Mn^IIPc⁻²/Mn^IIPc⁻³, E_1/2 = −0.68 V vs. Ag|AgCl) reductions were also observed for complex 3b. Spectroelectrochemistry was used to confirm these processes. Reduction process involving the metal (Mn^IIIPc⁻²/Mn^IIPc⁻²) was associated with the formation of manganese μ-oxo complex in complex 3a.     

Synthesis and characterization of [Fe(III)(qsal)2][M(III)(pds)2] (M = Cu, Au)

Salts of the Fe(III) spin crossover cation [Fe^III(qsal)₂]⁺ (qsalH = N-(8-quinolyl)salicylaldimine) and monoanions [M^III(pds)₂]⁻ (M = Cu, Au; pds = pirazine-2,3-diselenolate) with formula [Fe^III(qsal)₂][M^III(pds)₂] were prepared and characterized by single crystal X-ray diffraction and magnetic measurements. These two salts present magnetic properties essentially due to the Fe^III centres in the high-spin state (S = 5/2), and do not have any spin transition.     

Spectral and kinetic investigation on oxidation and reduction of water soluble porphyrin-manganese(III) complex

In this work the oxidation and reduction reactions of Mn^III-Coproporphyrin-I (Mn^III-CPI) have been studied and four forms of manganese-CPI complexes have been characterized. This complex was observed to be highly reactive (at basic pH) towards Mn(II), hypochlorite, hydrogen peroxide and oxone, forming [Mn^IV(O)CPI(OH)]⁻ that was unstable and, after a short time, formed again [Mn^IIICPI(OH)₂]⁻. With an excess of NaClO, a further oxidation of the complex [Mn^IV(O)CPI(OH)]⁻, provoked a significant spectral change for the [Mn^V(O)CPI(OH)] formation that showed, in the time, a partial polymerization. [Mn^IIICPI(OH)₂]⁻ was reduced by sodium dithionite to form the very unstable complex of [Mn^IICPI(OH)]⁻ that successively degraded with Mn(II) release.     

Vibrational and structural mapping of [Os(bpy)3] and [Os(phen)3]

Structural changes between [Os^IIL₃]²⁺ and [Os^IIIL₃]³⁺ (L: 2,2′-bipyridine; 1,10-phenanthroline) and molecular and electronic structures of the Os^III complexes [Os^III(bpy)₃]³⁺ and [Os^III(phen)₃]³⁺ are discussed in this paper. Mid-infrared spectra in the ν(bpy) and ν(phen) ring stretching region for [Os^II(bpy)₃](PF₆)₂, [Os^III(bpy)₃](PF₆)₃, [Os^II(phen)₃](PF₆)₂, and [Os^III(phen)₃](PF₆)₃ are compared, as are X-ray crystal structures. Absorption spectra in the UV region for [Os^III(bpy)₃](PF₆)₃ and [Os^III(phen)₃](PF₆)₃ are dominated by very intense absorptions (ε = 40 000-50 000 M⁻¹ cm⁻¹) due to bpy and phen intra-ligand π → π^∗ transitions. In the visible region, relatively narrow bands with vibronic progressions of ∼1500 cm⁻¹ appear, and have been assigned to bpy or phen-based, spin-orbit coupling enhanced, ¹π → ³π^∗ electronic transitions. Also present in the visible region are ligand-to-metal charge transfer bands (LMCT) arising from π(bpy) → t_2g(Os^III) or π(phen) → t_2g(Os^III) transitions. In the near infrared, two broad absorption features appear for oxidized forms [Os^III(bpy)₃](PF₆)₃ and [Os^III(phen)₃](PF₆)₃ arising from dπ-dπ interconfigurational bands characteristic of dπ⁵Os^III. They are observed at 4580 and 5090 cm⁻¹ for [Os^III(bpy)₃](PF₆)₃ and at 4400 and 4990 cm⁻¹ for [Os^III(phen)₃](PF₆)₃. The bpy and phen infrared vibrational bands shift to higher energy upon oxidation of Os(II) to Os(III). In the cation structure in [Os^III(bpy)₃](PF₆)₃, the Os^III atom resides at a distorted octahedral site, as judged by ∠N-Os-N, which varies from 78.78(22)° to 96.61(22)°. Os-N bond lengths are also in general longer for [Os^III(bpy)₃](PF₆)₃ compared to [Os^II(bpy)₃](PF₆)₂ (0.010 Å), and for [Os^III(phen)₃](PF₆)₃ compared to [Os^II(phen)₃](PF₆)₂ (0.014 Å). Structural changes in the ligands between oxidation states are discussed as originating from a combination of dπ(Os^II) → π^∗ (bpy or phen) backbonding and charge redistribution on the ligands as calculated by natural population analysis.     

New coordination polymer based on salpn Schiff base and azide bridging ligands: Synthesis and structural characterization of {Na[Co(μ-salpn)(μ1,1-N3)2]}n (H2salpn = N,N′-bis(salicylidene)-1,3-diaminopropane)

One-pot reaction of cobalt(II) nitrate hexahydrate Co(NO₃)₂ · 6H₂O with H₂salpn (N,N′-bis(salicylidene)-1,3-diaminopropane) in presence of a large excess of sodium azide (NaN₃) gives the new Co(III) compound {Na[Co^III(μ-salpn)(μ_1,1-N₃)₂]}_n (1), which was characterized by single crystal X-ray diffraction analysis. The crystal structure shows polymeric 1D complex generated by the hexadentate Schiff base salpn²⁻ and two crystallographically different azide ligands. The two nitrogen atoms of the salpn ligand are bonded to the cobalt(III) ion while each phenoxo oxygen atom is bonded to the same Co(III) ion and to two equivalent sodium ions. Each azide ligand acts with the end-on bridging coordination mode between Co(III) and Na(I) ions. The Co(III) ion adopts a distorted octahedral geometry arising from two oxygen and two nitrogen atoms of the salpn ligand and from two nitrogen atoms of the two crystallographically different azide ligands in trans positions. Such [Co(salpn)(N₃)₂] entities are connected each other by sodium ions through four oxygen atoms of two equivalent Schiff base ligands and two nitrogen atom of the two different azide ligands to generate the 1D structure of 1.