Ruthenium-azoimine-chloranilates Synthesis,Spectra and Electrochemistry of Ruthenium(II)-1-alkyl-2-(arylazo)imidazole-chloranilate Complexes

Ag⁺-assisted dechlorination of blue cis-trans-cis Ru(R-aai-R′)₂Cl₂ followed by the reaction with chloranilic acid (H₂CA) in the presence of Et₃N, gives a neutral mononuclear violet complex [Ru(R-aai-R′)₂(CA)]. [R-aai-R′=p-R-C₆H₄—N=N—C₃H₂—NN, abbreviated as an N,N′ chelator where N(imidazole) and N(azo) represent N and N′, respectively; R = H (a), OMe (b), NO₂ (c) and R′= Me (4), Et(5), Bz(6)]. All the complexes exhibit strong intense MLCT transitions in the visible region and weak broad bands at higher wavelength (>700 nm). Visible transitions (580–595 nm) show a negative solvatochromic effect. The cyclic voltammograms show two quasireversible to irreversible couples positive to SCE and are due to CA⁻/CA²⁻ (1.2–1.35 V) and Ru(III)/Ru(II) (1.6–1.8 V) redox processes. Three couples, negative to SCE, are assigned to CA²⁻/CA³⁻ (−0.2 to −0.3 V), and azo reductions (−0.5 to −0.7, −0.8 to −0.9 V) of the chelated R-aai-R′.     

Synthesis and reactivity of neodymium(III) amido-tethered N-heterocyclic carbene complexes

The reaction of the heteroleptic Nd(III) iodide, [Nd(L′)(N″)(μ-I)] with the potassium salts of primary aryl amides [KN(H)Ar′] or [KN(H)Ar^*] affords heteroleptic, structurally characterised, low-coordinate neodymium amides [Nd(L′)(N″)(N(H)Ar′)] and [Nd(L′)(N″)(N(H)Ar^*)] cleanly (L′ = t-BuNCH₂CH₂[C{NC(SiMe₃)CHNt-Bu}], N″ = N(SiMe₃)₂, Ar′ = 2,6-Dipp₂C₆H₃, Dipp = 2,6-Prⁱ₂C₆H₃, Ar^* = 2,6-(2,4,6-Prⁱ₃C₆H₂)₂C₆H₃). The potassium terphenyl primary amide [KN(H)Ar^*] is readily prepared and isolated, and structurally characterised. Treatment of these primary amide-containing compounds with alkali metal alkyl salts results in ligand exchange to give alkali metal primary amides and intractable heteroleptic Nd(III) alkyl compounds of the form [Nd(L′)(N″)(R)] (R = CH₂SiMe₃, Me). Attempted deprotonation of the Nd-bound primary amide in [Nd(L′)(N″)(N(H)Ar^*)] with the less nucleophilic phosphazene superbase Bu^tNP{NP(NMe₂)₃}₃ resulted in indiscriminate deprotonations of peripheral ligand CH groups.     

Mixed pseudohalide complexes of copper(II). Crystal and molecular structure of [Cu(N3)(NCS)(tmen)] n and of [Cu(N3)(NCO)(tmen)]2 (tmen = N,N,N′,N′-tetramethylethylenediamine)

The compounds [Cu(N₃)(NSC)(tmen)]_n (1), [Cu(N₃)(NCO)(tmen)]_n (2) and [Cu(N₃)(NCO)(tmen)]₂ (3) (tmen=N,N,N′,N′-tetramethylethylenediamine) were synthesized and studied by i.r. spectroscopy. Single crystals of compounds (1) and (3) were obtained and characterized by X-ray diffraction. The structure of compound (1) consists of neutral chains of copper(II) ions bridged by a single azido ligand showing the asymmetric end-to-end coordination fashion. Each copper ion is also surrounded by the other three nitrogen atoms; two from one N,N,N′,N′-tetramethylethylenediamine and one from a terminal bonded thiocyanate group. Compound (2) decomposes slowly in acetone and the product formed [Cu(N₃)(NCO)(tmen)]₂ (3) crystallizes in the monoclinic system (P2₁). The structure of (3) consists of dimeric units in which the Cu atoms are penta-coordinated and connected by μ(1,3) bridging azido and cyanate ligands. In both cases the five coordinated atoms give rise to a slightly distorted square-based pyramid coordination geometry at each copper ion. The thermal behavior of [Cu(N₃)(NSC)(tmen)]_n (1) and [Cu(N₃)(NCO)(tmen)]_n (2) were investigated and the final decomposition products were identified by X-ray powder diagrams.     

Electrosynthesis in a microemulsion using a novel cobaloxime catalyst

[Bis[μ-[(2,3-butanedione dioximato)(2-)-O:O′]]tetrafluorodiborato(2-)-N,N′,N″,N]cobalt (COBF, 1) was used as a catalyst for the conversion of trans-1,2-dibromocyclohexane (DBCH) to cyclohexene and the photoelectrochemical cyclisation of 2-(4-bromobutyl)-2-cyclohexen-1-one (BBC) to trans-1-decalone 2 in a microemulsion. Voltammetry showed clear evidence of catalytic behaviour and bulk electrolysis showed larger turnover numbers for both reactions when compared with the same system using vitamin B_12a as catalyst. For BBC, improved turnover may result from a relatively weak carbon–cobalt bond in the alkylcobalt intermediate of 1, and from better partition of 1 into the organic phase in which reactant BBC resides.     

A New Procedure for Preparing Perfluoroalkoxypropanoic Acid Fluorides

Condensation of perfluoro carboxylic acid fluorides with hexafluoropropene epoxide in the presence of N,N, N′,N′-tetraalkyldiaminomethanes was studied.__________Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 3, 2005, pp. 438–440.Original Russian Text Copyright © 2005 by Igumnov, Lekontseva, Shipigusev, Mukhametshin.     

Preparation of chiral diimino- and diaminodiphosphine ligands and their Cu and Ag complexes. X-ray crystal structures of [Cu(1S,2S-cyclohexyl-P2N2)][PF6] and [Ag(1R,2R-cyclohexyl-P2N2H4)][BF4]

The interaction of optically pure 1R,2R-diammoniumyclohexane mono-(+)-tartrate and 1S,2S-diammoniumcyclohexane mono-(−)-tartrate with 2 equiv. of o-(diphenylphosphino)benzaldehyde in the presence of 2 equiv. of potassium carbonate in a refluxing ethanol/water mixture gave the optically pure condensation products N,N′-bis[o-(diphenylphosphino)benzylidene]-1R,2R-diiminocyclohexane[1R,2R-cyclohexyl-P₂N₂, (R,R)-I] and N,N′-bis[o-(diphenylphosphino)benzylidene]-1S,2S-diiminocyclohexane [1S,2S-cyclohexyl-P₂N₂, (S,S)-I], respectively, in good yield. Reduction of optically pure (R,R)-I and (S,S)-I with NaBH₄ in ethanol gave the optically pure reduced products N,N′-bis[o-(diphenylphosphino)benzylidene]-1R,2R-diaminocyclohexane[1R,2R-cyclohexyl-P₂N₂H₄, (R,R)-II] and N,N′-bis[o-diphenylphosphine)benzylidene]-1S,2S-diaminocyclohexane[1S,2S-cyclohexyl-P₂N₂H₄, (S,S)-II], respectively, in good yield. The coordination behaviour of I and II toward salts of Cu^I and Ag^I have been examined. The interaction of [Cu(C)₃CN)₄][X] (X = ClO₄⁻, PF₆⁻) with 1 equiv. of optically pure L₄ [L₄ = (R,R)-I, (S,S)-I, (R,R)-II and (S,S)-II] gave the corresponding optically pure [CuL₄][X] complexes, III–VI IIIa, L₄ = (R,R)-I, X = PF₆⁻ IIIb, L₄ = (R,R)-I, X = ClO₄⁻ IV, X = PF₆⁻; Va, L₄ = (R,R)-II, X = PF₆⁻, Vb L₄ = (R,R)-II, X= ClO₄⁻, VI L₄ = (S,S)-II, X = PF₆⁻, in good yield. For the Cu^I complexes, the L₄ ligand acted as a tetradentate ligand. However, a variable-temperature ³¹P[¹H] NMR study of IIIb shows that at ambient temperature one of the imino groups of the tetradentate ligand undergoes rapid dissociation to form a tridentate ligand. The interaction of AgBF₄ with 1 equiv. of otpically pure L₄ [L₄ = (R,R)-I, (S,S)-I, (R,R)-II and (S,S)-II gave the corresponding optically pure [AgL₄][BF₄] complexes, VII–X VII L₄ = (R,R)-I; VIII, L₄ = (S,S)-I; IX,L₄ = (R,R)-II; X, L₄ = (S,S)-II], in good yield. For the Ag^I complexes, the L₄ ligand acted as a tetradentate ligand with the two amino groups coordinated unsymmetrically to the silver. A variable temperature ³¹P [¹H] NMR study of VII suggests that at high temperature the complex exists as a tri-coordinated complex. The structurers of IV and IX were established by X-ray diffraction studies.     

Oxidation of alcohols using a manganese (II) complex based on a pentakis benzimidazole amide ligand

A pentakis benzimidazole based penta-amide ligand diethylenetriamine—N,N,N′,N′,N″-pentakis(2-methyl benzimidazolyl)penta-amide [GBDTPA] has been synthesized and utilized to prepare Mn (II) complexes of general composition [Mn₂(GBDTPA)X₄], where X is an exogenous anionic ligand (X = Cl⁻, NO₃⁻ and Br⁻). The oxidation of alcohols has been investigated using [Mn₂(GBDTPA)Cl₄] as the catalyst and TBHP as an alternate source of oxygen. The respective aldehydic products have been isolated and characterized by ¹H NMR.     

Magnetic Structures of the Rare-Earth Platinum AluminidesRPtAl (R=Ce, Pr, Nd)

The rare-earth (R) platinum aluminidesRPtAl crystallize in the orthorhombic TiNiSi-type structure (space group Pnma,Z=4), where magnetic rare-earth atoms form a network of chains parallel to thea-axis and parallel to theb-axis. Magnetic structures and phase transitions ofRPtAl (R=Ce, Pr, Nd) compounds were investigated by systematic measurements of magnetic susceptibility, specific heat, and neutron diffraction on polycrystalline samples. The results reveal a large magnetocrystalline anisotropy and magnetic structures that are dominated by a ferromagnetic component parallel to one of the two chain directions: thea-axis for CePtAl and PrPtAl and theb-axis for NdPtAl. The complex magnetism of CePtAl with three successive magnetic phase transitions (T_C=5.9 K,T₂=4.3 K,T₃=2.5 K) and two coexisting propagation vectors (k₁=0 forT≤T_C, k_2i=[0, 0.46, 0] forT₂≤T≤T_C, k₂=[0, 1/2, 0] forT≤T₂) is confirmed to be exceptional amongRPtAl compounds. PrPtAl has a nonmagnetic crystalline-electric field (CEF) ground-state singlet separated by 21 K from the first-excited state CEF singlet and magnetic exchange interactions are strong enough to induce long-range magnetic order (Curie temperatureT_C=5.8 K, propagation vector k₁=0, magnetic group Pnm′a′, ordered saturation momentm₁=1.00(7)μ_B). NdPtAl is a simple ferromagnet (T_C=19.2 K, k₁=0, Pn′ma′,m₁=2.08(4)μ_B).     

In the presence of very fast comproportionation, sampled current voltammetry and rotating disk electrode voltammetry yield equal two versus one-electron limiting current ratios. Reconciliation through analysis of concentration profiles

A species having three sequential redox states is able to react with its higher oxidation (or lower reduction) state producing two equivalents of its middle redox state. A possible electrochemical signature of that comproportionation reaction is that the faradaic current from the two-electron process (I_1,1) might not be twice the current of the corresponding one-electron process (I_1,2). In this paper, using redox-active species with well-separated one- and two-electron processes, such as N,N′-di-n-heptylviologen, N-methyl-4-benzoylpyridinium perchlorate, TCNQ, TTF, N,N′-dimethylphenazine and TMPD, it is reported that within a wide range of the experimental parameters, two seemingly different electrochemical methods, namely sampled current voltammetry (SCV), a diffusion-controlled method, and rotating disk electrode (RDE) voltammetry, a convection-dominated method, give equal mass-transfer limited current ratios (I_1,2/I_1,1). These phenomena have been traced to the fact that close to the electrode distance-normalized concentration profiles generated from both SCV and RDE voltammetry are superimposable. Digital simulations have confirmed these conclusions, and have led to the elucidation of the relative roles of the comproportionation reaction rate constant, k_f, and the diffusion-layer thickness, δ, in determining the value of the (I_1,2/I_1.1)_{SCV or RDE} ratio: when the diffusion-layer is thicker, the comproportionation reaction time is longer and limiting (I_1,2/I_1,1) ratios are reached with lower k_f values. (The larger δ corresponds to longer sampling times in SCV and slower electrode rotation rates in RDE voltammetry.). Ultimately, the limiting values of the (I_1,2/I_1,1)_{SCV or RDE} ratios are controlled by the relative values of the diffusion coefficients of all three species involved in the comproportionation reaction. According to our results, the (I_1,2/I_1,1)_{SCV or RDE} ratio can afford kinetic information on the comproportionation reaction, and comprises a diagnostic criterion for the relative diffusion coefficients of a redox-active species and its one-electron oxidized (or reduced) form.     

Isotachophoretic determination of stability constants of Ho and Y complexes with diethylenetriaminepentaacetic acid and 1,4,7,10-tetraazadodecane-N,N′,N″,N-tetraacetic acid

The method of capillary isotachophoresis with conductivity detection was applied for the determination of the physico-chemical characteristics (conditional stability constants log β′) of holmium and yttrium complexes with DTPA (diethylenetriaminepentaacetic acid) and DOTA (1,4,7,10-tetraazadodecane-N,N′,N″,N-tetraacetic acid). The log β′ determination is based on the linear relation between the stability constants of lanthanide–DTPA (lanthanide–DOTA) complexes and the reduction of the zone of the complex owing to the bleeding phenomena (liberating free metal ion). The stability constants calculated using this relationship are comparable with the literary data obtained by other methods for both holmium (log β′_Ho–DTPA=21.9, log β′_Ho–DOTA=24.5) and yttrium complexes (log β′_Y–DTPA=21.2, log β′_Y–DOTA=24.4). Capillary isotachophoresis was applied for the determination of the optimum composition of the reaction mixture (metal:ligand ratio) as well.     

DNA-binding studies of mixed ligand cobalt(III) complexes

The DNA binding characteristics of mixed ligand complexes of the type [Co(en)₂(L)]Br₃ where en = N,N′-ethylenediamine and L = 1,10-phenanthroline (phen), 2,2′-bipyridine (bpy), 1,10-phenanthroline-5,6-dione (phendione), dipyrido[3,2-a:2′,3′-c]phenazine (dppz) have been investigated by absorption titration, competitive binding fluorescence spectroscopy and viscosity measurements. The order of intercalative ability of the coordinated ligands is dppz > phen > phendione > bpy in this series of complexes.     

Conformational dependence of the intrinsic acidity of the aspartic acid residue sidechain in N-acetyl- -aspartic acid-N′-methylamide

The sidechain conformational potential energy hypersurfaces (PEHS) for the γ_L, β_L, α_L, and α_D backbone conformations of N-acetyl- -aspartate-N′-methylamide were generated. Of the 81 possible conformers initially expected for the aspartate residue, only seven were found after geometric optimizations at the B3LYP/6-31G(d) level of theory. No stable conformers could be located in the δ_L, _L, γ_D, δ_D, and _D backbone conformations. The ‘adiabatic’ deprotonation energies for the endo and exo forms of N-acetyl- -aspartic acid-N′-methylamide were calculated by comparing their optimized relative energies against those found for the seven stable conformers of N-acetyl- -aspartate-N′-methylamide. Sidechain conformational PEHSs were also generated for the estimation of ‘vertical’ deprotonation energies for both endo and exo forms of N-acetyl- -aspartic acid-N′-methylamide. All backbone–sidechain (N–H⁻O–C) and backbone–backbone (N–HO=C) hydrogen bond interactions were analyzed. A total of two backbone–backbone and four backbone–sidechain interactions were found for N-acetyl- -aspartate-N′-methylamide. The deprotonated sidechain of N-acetyl- -aspartate-N′-methylamide may allow the aspartyl residue to form strong hydrogen bond interactions (since it is negatively charged) which may be significant in such processes as protein–ligand recognition and ligand binding. As a primary example, the molecular geometry of the aspartyl residue may be important in peptide folding, such as that in the RGD tripeptide.     

Amidines-XVIII: Tautomeric equilibria and pka values of N,N'-disubstituted amidines. Substituent effects

The influence of substitution of amidine group on tautomeric equilibria constants and basicities is discussed. Equations based on correlation analysis methods are derived enabling predictions of both, microscopic pK_a, values of individual tautomers, measured macroscopic pK_a values of the tautomeric mixture, as well as the tautomeric equilibrium constant (as pK_T). It is shown that pK_arn values of unsymmetrically N,N'-disubstituted amidines should obey a non-linear relation with σ° constants, and only for symmetrically N,N'-disubstituted amidines obey the linear Hammett equation. Tautomeric equilibrium constants of N,N'-disubstituted amidines correlate withσ° substituent constants. The methods of prediction of pK_a value of both tautomers and pK_T value are proposed.Derived relations are applied to the series of N,N'-diphenylacetamidines and benzamidines.     

Three new copper(II)–nickel(II) heterodinuclear complexes with the <Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N′</Emphasis>-bis(2-pyridyl-ethyl)oxamide dianion. Syntheses,spectra, and magnetic properties

Three new Cu(II)–Ni(II) heterodinuclear complexes: [Cu(PMoxd)Ni(phen)₂](ClO₄)₂ (1), [Cu(PMoxd)Ni(NO₂-phen)₂](ClO₄)₂ (2), [Cu(PEoxd)Ni(Me₂-bpy)₂](ClO₄)₂ (3), [where Cu(PMoxd)=N,N′-bis(pyridyl-methyl)oxamidatocopper(II), Cu(PExod)=N,N′-bis(2-pyridyl-ethyl)oxamidatocopper(II), phen=1,10-phenanthroline and NO₂-phen=5-nitro-1,10-phenanthroline and bpy=2,2′-bipyridine] were prepared and characterized by i.r. and electronic spectra, and by magnetic properties. The magnetic analysis was carried out by means of the theoretical expression of the magnetic susceptibility deduced from the spin Hamiltonian H=−2JS₁S₂, leading to J=−70.83 cm⁻¹ (1); −56.23 cm⁻¹ (2); −57.30 cm⁻¹ (3), indicating a weak antiferromagnetic spin–exchange interaction between Cu(II) and Ni(II) ions within three complexes.     

<Emphasis Type="Italic">N,N′</Emphasis>-Bis(triethoxysilylmethyl)thiocarbamide and Poly[<Emphasis Type="Italic">N,N′</Emphasis>-bis(silsesquioxanylmethyl)thiocarbamide <Emphasis Type="Italic">S,S</Emphasis>-dioxide]

Condensation of (aminomethyl)triethoxysilane with thiocarbamide in the presence of catalytic amounts of ammonium sulfate was used to synthesize N,N-bis(triethoxysilylmethyl)thiocarbamide. The latter was brought into oxidative hydrolytic polycondensation with H₂O₂ to obtain poly[N,N′-bis(silsesquioxanylmethyl)thiocarbamide S, S-dioxide] whose properties were compared with the properties of poly[N,N′-bis(silsesquioxanylpropyl)thiocarbamide S,S-dioxide]. Both polymers in highly acidic media rather strongly absorb Ag(I), while at pH 7 they reduce most absorbed Ag⁺ to the metal. Their reaction with potassium permanganate involves reduction of Mn⁷⁺ to Mn⁴⁺. The first polymer is a less effective sorbent and redox agent than the second.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 7, 2005, pp. 1154–1156.Original Russian Text Copyright © 2005 by Voronkov, Vlasova, Grigor’eva, Pozhidaev, Bol’shakova.     

Synthesis, crystal structure and characterization of iron pyroborate (Fe2B2O5) single crystals

Single crystals of iron(II) pyroborate, Fe₂B₂O₅, were prepared at 1000–1050 °C under an argon atmosphere. The crystals were transparent, yellowish in color and needle-like or columnar. The crystal structure of Fe₂B₂O₅ was analyzed by single-crystal X-ray diffraction. Refined triclinic unit cell parameters were a=3.2388(2), b=6.1684(5), c=9.3866(8) Å, α=104.613(3)°, β=90.799(2)° and γ=91.731(2)°. The final reliability factors of refinement were R1=0.020 and wR2=0.059 [I > 2σ(I)]. Transmittance over 50% in the visible light region from 500 to 750 nm was observed for a single crystal of Fe₂B₂O₅ with a thickness of about 0.3 mm. The light absorption edge estimated from a diffuse reflectance spectrum was at around 350 nm (3.6 eV). Magnetic susceptibility was measured for single crystals at 4–300 K. Fe₂B₂O₅ showed antiferromagnetic behavior below the Néel temperature, T_N≈70 K, and the Weiss temperature was T_W=36 K. The effective magnetic moment of Fe was 5.3μ_B.     

Heat capacity and magnetic phase transition of two-dimensional metal-assembled complex (NEt<Subscript>4</Subscript>)[{Mn<Superscript>III</Superscript>(salen)}<Subscript>2</Subscript>Fe<Superscript>III</Superscript>(CN)<Subscript>6</Subscript>]

Summary Heat capacity measurements of the two-dimensional metal-assembled complex, (NEt₄)[{Mn^III(salen)}₂Fe^III(CN)₆] [Et=ethyl, salen= N,N’-ethylenebis(salicylideneaminato) dianion], were performed in the temperature range between 0.2 and 300 K by adiabatic calorimetry. A ferrimagnetic phase transition was observed at T_c1=7.51 K. Furthermore, another small magnetic phase transition appeared at T_c2=0.78 K. Above T_c1, a heat capacity tail arising from the short-range ordering of the spins characteristic of two-dimensional magnets was found. The magnetic enthalpy and entropy were evaluated to be ΔH=291 J mol^-1 and ΔS=27.4 J K^-1 mol^-1, respectively. The experimental magnetic entropy agrees roughly with ΔS=Rln(5·5·2) (=32.5 J K^-1 mol^-1; R being the gas constant), which is expected for the metal complex with two Mn(III) ions in high-spin state (spin quantum number S=2) and one Fe(III) ion in low-spin state (S=1/2). The heat capacity tail above T_c1 became small by grinding and pressing the crystal. This mechanochemical effect would be attributed to the increase of lattice defects and imperfections in the crystal lattice, leading not only to formation of the crystal with a different magnetic phase transition temperature but also to decrease of the magnetic heat capacity and thus the magnetic enthalpy and entropy.     

Cobalt(II) complexes with aminopolycarboxylate 1,3-pdta-type ligands: synthesis and characterization of trans(O6)-[Mg(H2O)6][CoII(1,3-pddadp)]·H2O

Starting from Ba₂(1,3-pddadp)·8H₂O (1,3-pddadp=1,3-propanediamine-N,N′-diacetate-N,N′-di-3-propionate ion) and CoSO₄, a new hexadentate [Co^II(1,3-pddadp)]²⁻ complex has been prepared. The trans(O₆) geometry of this complex was confirmed by comparison of its i.r. and u.v.–vis. spectra with those of [Co^II(1,3-pdta)]²⁻ (1,3-pdta is the 1,3-propanediaminetetraacetate ion) and trans(O₆)-[Co^III(1,3-pddadp)]⁻ complexes of known X-ray crystal structure. Magnetic and electrolytic conductivity properties of these complexes have also been discussed.     

Crystal structure and magnetic properties of Sr4Mn2NiO9

The crystal structure of Sr₄Mn₂NiO₉ has been refined on single crystal. This phase belongs to the series A_1+x(A^′_xB_1–x)O₃ (x=1/3) related to the 2H-hexagonal perovskite. The structure contains transition metals in chains of oxide polyhedra (trigonal prisms and octahedra); neighboring chains are separated from each other by the Sr atoms. The sequence of the face sharing polyhedra along the chains is two octahedra + one trigonal prism. Mn occupies the octahedra and Ni is disordered in the trigonal prism with ≈80% in the pseudo square faces of the prism and ≈20% at the centre. This result has been confirmed by XANES experiments at Mn K and Ni K edges, respectively. Sr₄Mn₂NiO₉ is antiferromagnetic with a Néel temperature at T=3 K. The Curie constant measured at high temperature is in good agreement with ≈80% of the Ni²⁺ ions in the spin state configuration S=0.     

Heterometallic clusters arising from cubic Ni3M′O4 (M′=K and Na) entity: Solvothermal synthesis with/without the assistance of microwave

Solvothermal reaction assisted with microwave leads to the formation of two unique heterometallic cubic clusters [Ni₃M′(L)₃(OH)(CH₃CN)₃]₂·CH₃CN (M′=K for 1 and M′=Na for 2, where L is an anion of 2-[(2-hydroxy-3-methoxy-benzylidene)-amino]-ethanesulfonate) with higher efficiency, yields and purity than those without it. The 6-metallacrown-3 [Ni₃(OH)(L)₃]⁻ groups exhibit interesting ion trapping and self-assembly of size-different Na⁺ and K⁺ through form recognition and coordination activity in 1 and 2. The magnetic studies for 1 and 2 suggest that the {Ni₃M′O₄} (M′=K and Na) cores both display dominant ferromagnetic interactions from the nature of the binding modes of μ₃-O (oxidophenyl) and μ₃-OH.