Dinuclear Manganese Research Articles

Catalytic activity of a dinuclear manganese complex (MnMeTACN) on the oxidation of ethyl linoleate

Catalytic activity of a dinuclear manganese-based complex [Mn 2 IV (μ-O) 3 L 2 ](PF 6 ) 2 (MnMeTACN) (L = 1,4,7-trimethyl-1,4,7-triazacyclononane), and its combination with a polyamine, 1,1,4,7,10,10-hexamethyltriethylenetetramine (HMTETA), was investigated on the oxidation of ethyl linoleate (EL). When MnMeTACN was molecularly mixed with EL in a co-solvent (methanol), MnMeTACN alone was found to be a very active catalyst for the oxidation of unpurifed EL (containing a small amount of hydroperoxides), similar to the catalytic activity of a Co-based catalyst. For purified EL (free of hydroperoxides), the addition of tert -butyl hydroperoxide was necessary to rapidly initiate the EL oxidation. A tentative catalytic cycle for MnMeTACN was proposed on the basis of electrospray ionization mass spectrometry (ESI-MS) investigation. The existence of HMTETA significantly accelerated the decomposition of the formed hydroperoxides into alkoxy free radicals, which in turn led to a high level of volatile aldehyde byproducts due to β-scission reactions. The catalytic activity of a dinuclear manganese-based complex, [Mn IV 2 (μ-O) 3 L 2 ](PF 6 ) 2 (MnMeTACN) on the oxidation of ethyl linoleate (EL) was found to be similar to that of a Co-based catalyst. The presence of hydroperoxide was necessary to rapidly initiate the EL oxidation. A tentative catalytic cycle for MnMeTACN was proposed on the basis of ESI-MS investigation.

Metallacumulenes as Potential Electron Reservoir Devices

This paper reviews recent work in the area of organomanganese chemistry whose purpose is the design of single-molecule components for electronics. This field has recently received much attention in the pursuit of continued miniaturization of electronics. Electron reservoirs and molecular wires are basic motifs of single-electron devices. Both can accept and release electrons in a reversible fashion, but the former can also store electrons. Our recent work in the field deals with complexes of two distinct types: mononuclear half-sandwich manganese(I) vinylidene complexes, designed for application as electron reservoirs, and half-sandwich dinuclear manganese complexes and the bis-dmpe dinuclear MnII/MnII compounds, which were designed to serve as molecular wires. However, this review will focus on the mononuclear half-sandwich manganese(I) vinylidene and butatrienylidene systems, which have been synthetically successful systems and are supported by extensive DFT calculations and further detailed investigations using NMR, IR, UV−vis, and Raman spectroscopy, CV, magnetic susceptibilities, and X-ray diffraction studies.

Crystal structure of the diadenosine tetraphosphate hydrolase from Shigella flexneri 2a

Crystal structure of the diadenosine tetraphosphate hydrolase from <i>Shigella flexneri</i> 2<i>a</i>

Identification of the Dinuclear and Tetranuclear Air‐Oxidized Products Derived from Labile Phenolate‐Bridged Dimanganese(II) Pyridyl‐Chelate Compounds

AbstractDioxygen‐sensitive dinuclear manganese complexes of the phenoxo‐hinged dinucleating ligand 2,6‐bis{[N,N′‐bis(2‐picolyl)amino]methyl}‐4‐tert‐butylphenolato (bpbp–) containing exogenous labile THF, water and perchlorato ligands are described. The manganese(II) complexes [Mn2(bpbp)(ClO4)2(THF)]+ (1) and [Mn2(bpbp)(ClO4)(H2O)2]2+ (2) have been isolated as the salts 1·ClO4·THF·3H2O, 1·B(C6H5)4·4THF and 2·(ClO4)2·H2O. Complexes 1 and 2 are spontaneously oxidised in air in solution and the solid state. The reaction products of the air oxidation in THF, water and methanol solutions are labile dinuclear MnII–MnIII, MnIII2 and MnIII–MnIV complexes containing water‐ and methanol‐derived exogenous ligands. In addition, a Mn4 complex has been isolated. Magnetic susceptibility data confirm the MnII–MnIII oxidation state assignment with an S = 2/S = 5/2 model with weak antiferromagnetic coupling (J = –3.7 cm–1) in [Mn2(bpbp)(CH3O)2(H2O)2](ClO4)2 [3·(ClO4)2]. A tetranuclear complex, [Mn4(O)4–n(OH)n(bpbp)2](ClO4)4 [n = 1 or 2; 7·(ClO4)4], recovered from THF shows a Mn4O6 adamantane‐type core with the O bridges furnished by the two phenolato groups and four hydroxide/oxide bridges. We have arrived at two feasible formulations for the core metal oxidation states and oxo‐bridge protonation states, namely [MnIII4(O)2(OH)2(bpbp)2]4+ and [MnIII3MnIV(O)3(OH)(bpbp)2]4+, for 7, on the basis of a bond valence sum analysis of the crystal structure, elemental analysis and XANES. Thus, complex 7 is at least two oxidation state levels lower than known complexes with the Mn4O6 adamantane core structure. The magnetism of 7 was fitted well to an MnIII4 three‐J model. Complex cations related to 3 by homology, and to 7 by hydration/solvation, have been identified by ESI mass spectrometry. The [Mn2(bpbp)(OH)2(H2O)2]2+ ion (4) present in aqueous solutions on dissolution of 1·ClO4·THF·3H2O in air or by simple dissolution of 3 in water‐containing solvent is isoelectronic to 3. In the presence of significant amounts of water the MnII–MnIII complexes 3 and 4 are susceptible to further metal oxidation and concomitant aquo ligand deprotonation to give ions assignable to [MnIII/IV2(bpbp)O(OCH3)2(H2O)]2+ (5) and [MnIII2(bpbp)(OH)3(H2O)]2+ (6). ESI mass spectra of water or methanol solutions of 1, 2, 3 and 7 show predominantly an ion assignable to the oxide [Mn2(bpbp)(O)]2+ (8). Cation 8 is most likely not present in solution. Using mild source conditions and MS‐MS techniques, the gas‐phase fragmentation pathways to generate 8 have been mapped. (© Wiley‐VCH Verlag GmbH &amp; Co. KGaA, 69451 Weinheim, Germany, 2006)

High-valent bis(oxo)-bridged dinuclear manganese oxamates: Synthesis, crystal structures, magnetic properties, and electronic structure calculations of bis(μ-oxo)dimanganese(IV) complexes with a binucleating o-phenylenedioxamate ligand

Two novel bis(oxo)-bridged dinuclear manganese(IV) complexes with the binucleating ligand o-phenylenebis(oxamate) (opba), formulated as (Me 4N) 4[Mn 2O 2(opba) 2] ( 1a) and (Me 4N) 2(Ph 4P) 2[Mn 2O 2(opba) 2] · 8H 2O ( 1b), have been synthesized and characterized structurally and magnetically. Like the parent complex (Ph 4P) 4[Mn 2O 2(opba) 2] · 4H 2O ( 1c), they possess unique Mn 2(μ-O) 2 bridging cores with two additional o-phenylenediamidate bridges which lead to exceptionally short Mn–Mn distances (2.63–2.67 Å) and fairly bent Mn–O–Mn angles (93.8–95.5°). Complexes 1a– c show a moderate to strong antiferromagnetic coupling between the two high-spin Mn IV ions through the bis(oxo)bis( o-phenylenediamidate) quadruple bridge (− J = 70–164 cm −1; H = − JS 1 · S 2). Along this series, the − J values increase with the shortening of the Mn–Mn distance and/or the lessening of the Mn–O–Mn angle. Electronic structure calculations on model complexes reproduce the observed dependence of − J with the Mn–O–Mn angle at short intermetallic distances, and reveal that the magnetic coupling is dominated by the in-plane 3 d x 2 - y 2 type superexchange pathway via the oxo bridges with a small but nonnegligible contribution from direct 3 d x 2 - y 2 type Mn–Mn σ-bond.

Highly efficient oxidation of alcohols by the system &amp;quot;hydrogen peroxide-[lmn(o)3mnl](pf6)2 (l = 1,4,7-trimethyl-1,4,7-triazacyclononane)-oxalic acid&amp;quot;

The dinuclear manganese(IV) complex [LMn(O)3MnL](PF6)2 (1, L = 1,4,7-trimethyl-1,4,7-triazacyclononane) catalyzes the extremely efficient oxidation of alcohols with hydrogen peroxide at room temperature. Oxalic acid is an obligatory co-catalyst. The oxidation of isopropanol, for example, yields acetone with turnover numbers up to 40000 after 5-10 h in the absence of a solvent. 2-Cyanoethanol was oxidized by this system with somewhat lower efficiency (conversion 70%). The catalytically active cation from salt 1 was obtained in an insoluble form containing a heteropoly anion [Mn2O3(TMTACN)2]2[SiW12O40]. Oxidation of 2-cyanoethanol using this heterogenized catalyst and oxalic acid gave the oxo-products with the 54% total yield.

Carvone epoxidation by system “hydrogen peroxide-[Mn2L2O3][PF6]2 (L = 1,4,7-trimethyl-1,4,7-triazacyclononane)-carboxylic acid”: a combinatorial approach to the process optimization

Epoxidation of natural terpene (+)-carvone by the system consisting of a catalyst, oxalic acid (co-catalyst) and H2O2 (70% aqueous solution; oxidant) was studied and factorial design methods were applied for the optimization of this reaction. A dinuclear manganese(IV) complex [LMn(O)3MnL](PF6)2 (L = 1,4,7-trimethyl-1,4,7-triazacyclononane) was used as a catalyst, and acetonitrile was employed as a solvent. An analysis by methods of the complete 24 factorial design showed that an increase in the catalyst concentration gives a strong positive effect on the carvone conversion and selectivity. Hydrogen peroxide has a smaller positive effect on the conversion, but at high concentration, H2O2 leads to some decrease in the selectivity. An increase in the oxalic acid concentration has a beneficial effect on the conversion, but does not affect the selectivity.

Synthesis, crystal structure and magnetic properties of two new manganese Schiff base complexes [Mn 2(L 1) 2(NCS) 2] and [Mn(L 2)(N 3)(H 2O)] [{L 1H = C 13H 10N 2O 2}; {L 2H 2 = C 19H 22N 2O 4}

A μ 2-dicarboxylato bridged dinuclear manganese(II) Schiff base complex [Mn 2(L 1) 2(NCS) 2] ( 1), { L 1 = C 13 H 9 N 2 O 2 - } and a mononuclear manganese(III) Schiff base complex [Mn(L 2)(N 3)(H 2O)] ( 2), { L 2 = C 19 H 20 N 2 O 4 - 2 } have been synthesised and characterised by elemental analysis, IR and UV–Vis spectra (only complex 2). Structures of both the complexes are established by single crystal X-ray analysis. A variable temperature magnetic susceptibility measurement study has been performed for complex 1 and the result indicates there is a very weak antiferromagnetic interaction ( J = −0.41 ± 0.02 cm −1) between the two manganese(II) centres. Complex 2 forms a dimer through strong hydrogen bonding and the room temperature magnetic moment value shows there is no significant interaction between the low spin manganese(III) centres connected through hydrogen bonds.

Bleach and oxidation catalysis by manganese–1,4,7-triazacylononane complexes and hydrogen peroxide

The dinuclear manganese compound, [Mn IV 2(μ-O) 3(Me 3tacn) 2](PF 6) 2 ( 1) with Me 3tacn = 1,4,7-trimethyl-1,4,7-triazacyclononane, catalyzes a variety of bleaching processes and organic substrate oxidations using hydrogen peroxide as oxidant. Bleaching reactions in aqueous solution include stain bleaching for laundry cleaning, stain and starch removal for machine dishwash cleaning, and wood pulp bleaching. Model substrate conversions indicate that in aqueous and non-aqueous media ( 1) catalyzes both oxygen and electron-transfer reactions. A wide variety of substrates are efficiently converted in non-aqueous media, like alkenes into epoxides and cis-diols, alkanes into their corresponding alcohols and ketones, alcohols into aldehydes and sulfides into sulfoxides and sulfones. Yield and selectivity of reactions frequently depend on the conditions chosen. Dismutation of H 2O 2 can be controlled by using the appropriate solvent (e.g. acetone) or applying an additive, like oxalate or ascorbic acid. Addition of trichloroacetic acid 2,6-dichlorobenzoic acid to ( 1)/H 2O 2 has been shown to give a selective cis-dihydroxylation versus epoxidation (7:1 ratio).

Studies of a Dinuclear Manganese Complex with Phenoxo and Bis-acetato Bridging in the Mn2(II,II) and Mn2(II,III) States: Coordination Structural Shifts and Oxidation State Control in Bridged Dinuclear Complexes

The dinucleating ligand, 2,6-bis{[(2-(2-pyridyl)ethyl)(2-pyridylmethyl)-amino]-methyl}-4-methylphenol) (L1OH) reacts with Mn(ClO4)2.6H2O to form the dinuclear complex [Mn2(II,II)(L1O)(mu-OOCCH3)2]ClO4 (1). The electrolytic oxidation of 1 at 0.7 V (vs Ag/AgCl) produces the mixed valent complex [Mn2(II,III)(L1O)(mu-OOCCH3)2](ClO4)2 (1ox) quantitatively, while electrolysis at 0.20 V converts 1ox back to 1. X-ray crystallographic structures show that both 1 and 1ox are dinuclear complexes in which the two manganese ions are each in distorted octahedral coordination environments bridged by the phenoxo oxygen and two acetate ions. The structural changes that occur upon the oxidation 1 to 1ox suggest an extended pi-bonding system involving the phenoxo ring C-O(phenoxo)-Mn(II)-N(pyridyl) chain. In addition, as 1 is oxidized to 1ox, the rearrangements in the coordination sphere resulting from the oxidation of one Mn(II) ion to Mn(III) are transmitted via the bridging Mn-O(phenoxo) bonds and cause structural changes that render the site of the second manganese ion unfit for the +3 state and hence unstable to reduction. Thus the electrolytic oxidation of 1ox in acetonitrile at 1.20 V takes up slightly greater than 1 F of charge/mol of 1ox, but the starting complex, 1ox, is recovered, showing the instability of the Mn2(III,III) state that is formed with respect to reduction to 1ox. Variable-temperature magnetic susceptibility measurements of 1 and 1ox over the temperature range from 1.8 to 300 K can be modeled with magnetic coupling constants J = -4.3 and -4.1 cm(-1), respectively showing the weak antiferromagnetic coupling between the two manganese ions in each dinuclear complex, which is commonly observed among similar phenoxo- and bis-1,3-carboxylato-bridged dinuclear Mn2(II,II) and Mn2(II,III) complexes.

Chemistry and reactivity of dinuclear manganese oxamate complexes: Aerobic catechol oxidation catalyzed by high-valent bis(oxo)-bridged dimanganese(IV) complexes with a homologous series of binucleating 4,5-disubstituted- o-phenylenedioxamate ligands

The high-valent bis(oxo)-bridged dimanganese(IV) complexes with the series of binucleating 4,5-X 2- o-phenylenebis(oxamate) ligands (opbaX 2; X = H, Cl, Me) ( 1a– c) have been synthesized and characterized structurally, spectroscopically and magnetically. Complexes 1a– c possess unique Mn 2(μ-O) 2 core structures with two o-phenylenediamidate type additional bridges which lead to exceptionally short Mn–Mn distances (2.63–2.65 Å) and fairly bent Mn–O–Mn angles (94.1°–94.6°). The cyclovoltammograms of 1a– c in acetonitrile (25 °C, 0.1 M Bu 4NPF 6) show an irreversible one-electron oxidation peak at moderately high anodic potentials ( E ap = 0.50–0.85 V versus SCE), while no reductions are observed in the potential range studied (down to −2.0 V versus SCE). These dinuclear manganese oxamate complexes are excellent catalysts for the aerobic oxidation of 3,5-di- tert-butylcatechol to the corresponding o-quinone in acetonitrile at 25 °C. The order of increasing catecholase activity ( k obs) with the electron donor character of the ligand substituents as 1b (X = Cl) < 1a (X = H) < 1c (X = Me) correlates with Hammett σ + values ( ρ = −0.95). A mechanism involving initial activation of the catechol substrate by coordination to the dimetal center and subsequent oxidation to quinone by O 2 is proposed, which is consistent with the observed saturation kinetics.

Organosulfur oxidation by hydrogen peroxide using a dinuclear Mn-1,4,7-trimethyl-1,4,7-triazacyclononane complex

A mechanistic study of organosulfide oxidation by H2O2, using a dinuclear manganese complex as the catalyst, has revealed an unusual switch in the philicity of the oxidant for the first and the second oxygen transfer steps; this switch has been exploited to tune selectivity for each of the products.

Dinuclear manganese complexes containing 1,4-dimethyl-1,4,7-triazacyclononane ligands as well as carboxylato and oxo bridges

The reaction of 1,4-dimethyl-1,4,7-triazacyclononane (L-Me 2) with MnCl 2 · 4H 2O in acetonitrile gives, in the presence of sodium formate, hydrogen peroxide, triethylamine and KPF 6, the dinuclear Mn(III)–Mn(IV) complex cation [(L-Me 2) 2Mn 2(O) 2(OOCH)] 2+ ( 1) which crystallises as the hexafluorophosphate salt.The analogous reaction with sodium benzoate, however, yields the dinuclear Mn(III)–Mn(III) complex cation [(L-Me 2) 2Mn 2(O)(OOCC 6H 5) 2] 2+ ( 2), isolated also as the hexafluorophosphate salt.In the case of sodium acetate, both cations, the Mn(III)–Mn(IV) complex [(L-Me 2) 2Mn 2(O) 2(OOCCH 3)] 2+ ( 3) and the known Mn(III)–Mn(III) complex [(L-Me 2) 2Mn 2(O)(OOCCH 3) 2] 2+ ( 4) are available, depending upon the molar ratio.The single-crystal X-ray structure analyses show for the green crystals of [ 1][PF 6] 1.5[Cl] 0.5 · 1.5 H 2O and [ 3][PF 6] 2 · (CH 3) 2CO, a Mn–Mn distance of 2.620(2) and 2.628(4) Å, respectively, while for the red-violet crystal of [ 4][PF 6] 2, a Mn–Mn distance of 3.1416(8) Å is observed.All four compounds show catalytic activity for the oxidation of isopropanol with hydrogen peroxide in water and in acetonitrile to give acetone in the presence of oxalic or ascorbic acid as co-catalysts.

Oxidative drying of alkyd paints catalysed by a dinuclear manganese complex (MnMeTACN)

The application of a dinuclear manganese complex (MnMeTACN) as a catalyst in the oxidative drying of alkyd coatings is described. Experimental results on the film properties (drying time and film hardness) for various solvent- and water-borne alkyd coatings demonstrate that MnMeTACN is a potential alternative for commercially-available Co- and Mn-based catalysts. MnMeTACN appears to be suitable for both water-borne and solvent-borne alkyd systems. Confocal Raman microscopy is used to study the depth profile of the drying of alkyd coatings catalysed by different catalysts, and it has been found that slow surface drying is somewhat compensated by relatively fast deep layer drying.

Synthesis and studies of spectroscopic and electrochemical properties of dinuclear ruthenium(II) and manganese(II) complexes

New dinuclear ruthenium manganese complexes of general composition (bpy)2Ru(L)MnClx(H2O)2 (L is 1,10-phenanthroline-5,6-dione, 3,3′-dicarboxy-2,2′-bipyridyl, or bis(pyrazolyl); x = 2 or 4) were synthesized by the reaction of (bpy)2Ru(L) with MnCl2 · 4H2O. These compounds and the starting mononuclear ruthenium complexes were studied by spectrophotometric and electrochemical methods in MeCN. The position of the charge-transfer band RuII → L in the spectra depends on the donor-acceptor characteristics of the ligand L. For the dinuclear complex under study, the formal potentials of reversible one-electron oxidation of RuII are in the range of 0.9–1.2 V (vs. the standard hydrogen electrode), whereas oxidation of MnII occurs at more positive (by 0.1–0.2 V) potentials.

Electron Spin−Lattice Relaxation of the S0State of the Oxygen-Evolving Complex in Photosystem II and of Dinuclear Manganese Model Complexes

The temperature dependence of the electron spin-lattice relaxation time T1 was measured for the S0 state of the oxygen-evolving complex (OEC) in photosystem II and for two dinuclear manganese model complexes by pulse EPR using the inversion-recovery method. For [Mn(III)Mn(IV)(mu-O)2 bipy4]ClO4, the Raman relaxation process dominates at temperatures below 50 K. In contrast, Orbach type relaxation was found for [Mn(II)Mn(III)(mu-OH)(mu-piv)2(Me3 tacn)2](ClO4)2 between 4.3 and 9 K. For the latter complex, an energy separation of 24.7-28.0 cm(-1) between the ground and the first excited electronic state was determined. In the S0 state of photosystem II, the T1 relaxation times were measured in the range of 4.3-6.5 K. A comparison with the relaxation data (rate and pre-exponential factor) of the two model complexes and of the S2 state of photosystem II indicates that the Orbach relaxation process is dominant for the S0 state and that its first excited state lies 21.7 +/- 0.4 cm(-1) above its ground state. The results are discussed with respect to the structure of the OEC in photosystem II.

Oxidations by the system “hydrogen peroxide–[Mn 2L 2O 3][PF 6] 2 (L = 1,4,7-trimethyl-1,4,7-triazacyclononane)–oxalic acid”. Part 6. Oxidation of methane and other alkanes and olefins in water

Oxidation of alkanes with hydrogen peroxide in water solution at 10–50 °C is efficiently catalyzed by the cationic dinuclear manganese (IV) derivative [Mn 2L 2O 3] 2+ ( 1, with L = 1,4,7-trimethyl-1,4,7-triazacyclononane, TMTACN) in the form of the hexafluorophosphate salt ([ 1][PF 6] 2) if oxalic acid is present as a co-catalyst. Methane gives methanol and formaldehyde (turnover numbers, TONs, were 7 and 2, respectively, after reduction of the reaction mixture with ascorbic acid) whereas cyclohexane was oxidized with TONs up to 160 affording cyclohexyl hydroperoxide, cyclohexanone and cyclohexanol (the ketone was the main product, although at room temperature almost pure alkyl hydroperoxide was formed). In contrast to the oxidation in acetonitrile, the reaction with linear n-alkanes in water exhibits an unusual distribution of oxygenates. For example, in the oxidation of n-heptane the normalized reactivity of the methylene group in position 4 of the chain is 3–7 times higher than that of the CH 2 group in position 2. Dec-1-ene is epoxidized by hydrogen peroxide in water (a biphasic system) catalyzed by [ 1][PF 6] 2 and oxalic acid in the presence of a small amount of acetonitrile with TONs up to 1000 (no epoxidation has been detected in the absence of MeCN).

Pillared salicylaldehyde derivatives as building blocks for the design of cofacial salen-type ligands

The syntheses of pillared salicylaldehyde derivatives on a naphthalene block are reported. These compounds can be considered as building blocks for the elaboration of cofacial salen-typed ligands. The X-ray structure of a dinuclear manganese(III) complex is described, supporting our strategy to build topologically controlled multinuclear metal complexes.

High-field EPR investigations of MnIIIMnIV and MnIIMnIII states of dimanganese catalase and related model systems

Multi-frequency EPR experiments at 9, 34 and 94 GHz are reported on the antiferromagnetically coupled mixed valence Mn(II)Mn(III) complex of manganese catalase and on several dinuclear manganese model systems. They are compared with similar experiments obtained earlier for the Mn(III)Mn(IV) states. It is demonstrated how accurate information on the G- and 55Mn hyperfine tensors can be derived from this approach. Furthermore, the effect of oxidation state, planarity of the manganese-oxygen core and the type of ligands bridging the manganese ions on the magnetic resonance parameters and the related electronic structure is investigated. 'Broken-symmetry' density functional calculations on two Mn(III)Mn(IV) complexes, including the superoxidized state of the catalase, are presented. The agreement between calculated and experimental EPR parameters and complex geometries is remarkably good. Implications of these results for the structure and function of the dimanganese catalase are discussed.

Solvothermal synthesis, crystal structure and magnetic property of a new dinuclear manganese(II)–azido complex: [Mn(2,2′-dpa)(N 3) 2] 2 (2,2′-dpa = 2,2′-dipicolylamine)

A new dinuclear manganese(II)–azido complex: [Mn(2,2′-dpa)(N 3) 2] 2 1 (2,2′-dpa = 2,2′-dipicolylamine) has been synthesized solvothermally. X-ray crystallography analysis reveals that it consists of two crystallographically independent dimeric manganese moieties; each manganese(II) atom is coordinated by one 2,2′-dipicolylamine, one terminal azido ligand, and double end-on bridging azido ligands, exhibiting a slightly distorted octahedral sphere. There are extensive short contacts among dimeric manganese moieties, which extend the structure into an interesting three-dimensional supramolecular array. Magnetic determination of 1 indicates that dominant ferromagnetic interaction and weak antiferromagnetic interaction, which are ascribed to the end-on azido bridges and the short contacts, respectively, co-exist in this complex.