Synthesis, crystal structure and magnetic properties of a novel complex Ni(NIT2-thz)3(ClO4)2

A novel Ni(II)-nitronyl nitroxide-substituted thiazole complex, Ni(NIT2-thz)₃(ClO₄)₂ (NIT2-thz = 2-(2′-thiazole)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) was synthesized and characterized structurally and magnetically. It crystallizes in the monoclinic space group P2₁c. The metal coordination sphere is fully occupied by three chelating nitroxide ligands, showing a distorted octahedral geometry. The complex molecules were connected as 1-D chain structure by the intermolecular interaction. Magnetic studies show that antiferromagnetic couplings occurred between the nickel(II) ion and the organic radicals, and ferromagnetic between the adjacent molecules.     

Structure and thermal behavior of the layered zincophosphate [NH3-CH2-CH(NH3)-CH3](ZnPO4)2

A zinc phosphate with the composition [NH₃-CH₂-CH(NH₃)-CH₃](ZnPO₄)₂, containing the doubly protonated 1,2-diaminopropane (abbr. HDAP), was synthesized by hydrothermal crystallization of zinc nitrate, phosphoric acid, 1,2-diaminopropane and trimethylenedipiperidine. The single crystal analysis shows a layered inorganic-organic structure built up of a sandwich-like motif of alternating inorganic layers and HDAP cations (trimethylenedipiperidine not being a constituent of the structure). The HDAP species are found to be disordered and serve as bridges between two adjacent inorganic layers which are separated by 3.95 Å. The bridging interaction occurs via a hydrogen-bonding network. The inorganic layer features a pattern of four-membered rings involving two ZnO₄ and two PO₄ tetrahedra connected by sharing O atoms. Thermal analysis shows that the compound is stable up to 370 °C and that the thermal decomposition of HDAP occurs in two steps between 370 and 460 °C, causing the collapse of the structure. The first decomposition step corresponds to ammonia removal which proceeds with a high activation energy (E_a = 282 kJ mol⁻¹). The high E_a value is mainly attributed to strong electrostatic interactions between organic cations and anionic inorganic layers, the disruption of the interactions being the main reason for structural collapse after the HDAP removal.     

Hydrothermal synthesis and characterization of a zinc-substituted gallium phosphite, [H3N(CH2)2NH3]1/2 · [GaZn(HPO3)3(H2O)2]

An organically templated zinc-substituted gallium phosphite, [H₃N(CH₂)₂NH₃]_1/2 · [GaZn(HPO₃)₃(H₂O)₂] was synthesized under mild hydrothermal conditions in the presence of ethylenediamine (en) as structure-directing agent and characterized by single-crystal X-ray diffraction analysis. It crystallizes in the orthorhombic space group Pbcn with unit cell parameters: a = 18.6146(10) Å, b = 11.0454(6) Å, c = 10.9074(4) Å, V = 2242.62(19) Å³ and Z = 8. This compound has a three-dimensional framework built up from secondary building units (SBU) of Ga(III) (or Zn(II)) and HPO₃ pseudopyramid by sharing vertices. The structure displays a two-dimensional channel system running along the [0 0 1] and [0 1 0] direction with 5-, 8- and 10-membered rings. The diprotonated ethylenediamine template molecules are located in the channels. In this structure, some of the Ga(III) sites are occupied by Zn(II) atoms. The compound was also characterized by IR spectroscopy, inductively coupled plasma (ICP), X-ray photoelectron spectra (XPS), differential thermal and thermogravimetric analyses.     

Spectral properties and bio-activity of copper(II) clofibriates, part III: crystal structure of Cu(clofibriate)2(2-pyridylmethanol)2, Cu(clofibriate)2(4-pyridylmethanol)2(H2O) dihydrate, and Cu2(clofibriate)4(N,N-diethylnicotinamide)2

New copper(II) clofibriates (clof, {2-(4-chlorophenoxy)-2-methylpropionic or 2-(4-chlorophenoxy)isobutyric acid}) of composition Cu(clof)₂L₂ (where L=2-pyridylmethanol (2-pymeth) (1), N-methylnicotinamide (Menia) (4), N,N-diethylnicotinamide (Et₂nia) (5), isonicotinamide (isonia) (7) or methyl-3-pyridylcarbamate (mpc) (8)), [Cu(clof)₂(4-pymeth)₂(H₂O)] · 2H₂O (4-pymeth=4-pyridylmethanol) (2 · 2H₂O) and Cu(clof)₂L (where L=4-pymeth (3) or Et₂nia (6)) have been prepared and spectroscopically characterized. All the Cu(clof)₂L₂ compounds seem to possess distorted octahedral copper(II) stereochemistry with differing tetragonal distortions. An X-ray analysis of 1 was carried out and it featured a tetragonal-bipyramidal geometry around the copper(II) atom. X-ray analysis of 2 · 2H₂O featured a square-pyramidal geometry around copper(II) atom. Both the Cu(clof)₂L compounds seem to consist of a binuclear unit of tetracarboxylate type bridging. An X-ray analysis of 6 revealed typical binuclear paddle-wheel type structure, consisting of two copper(II) atoms in square-pyramidal geometry bridged by four carboxylate anions in the xy-plane. All complexes under study were characterized by EPR and electronic spectroscopy. The antimicrobial effects have been tested on various strains of bacteria, yeasts and filamentous fungi.     

Kinetic studies of the reduction of hexaaquacobalt(III) perchlorate by a cobaloxime, [Co(dmgBF2)2(H2O)2]

The reaction of with Co(dmgBF₂)₂(H₂O)₂ in 1.0 M HClO₄/LiClO₄ was found to be first-order in both reactants and the [H⁺] dependence of the second-order rate constant is given by k_2obs = b/[H⁺], b at 25 °C is 9.23 ± 0.14 × 10² s⁻¹. The [H⁺] dependence at lower temperatures shows some saturation effect that allowed an estimate of the hydrolysis constant for as K_a = 9.5 × 10⁻³ M at 10 and 15 °C. Marcus theory and the known self-exchange rate constant for Co(OH₂)₅OH^2+/+ were used to estimate an electron self-exchange rate constant of k₂₂ = 1.7 × 10⁻⁴ M⁻¹ s⁻¹ for .     

Low-dimensional compounds containing cyano groups. XIX. Crystal structure, spectroscopic, thermal and magnetic properties of {[Cu(tn)2]3[Pt(CN)4]2}[Pt(CN)4] (tn = 1,3-diaminopropane) complex

Violet prismatic crystals of {[Cu(tn)₂]₃[Pt(CN)₄]₂}[Pt(CN)₄] (tn = 1,3-diaminopropane) were crystallized from the water-methanol solution containing CuCl₂·2H₂O, tn and K₂[Pt(CN)₄]·3H₂O. Prepared complex was characterized using elemental analysis, infrared and UV-Vis spectroscopy, magnetic measurement and thermal analysis. X-ray analysis revealed an ionic character of the complex containing mononuclear square planar [Pt(CN)₄]²⁻ complex anions and penta-nuclear [Cu(tn)₂-Pt(CN)₄-Cu(tn)₂-Pt(CN)₄-Cu(tn)₂]²⁺ complex cations. The inner Cu(II) atom of the complex cation is hexa-coordinated, whereas two crystallographically equivalent peripheral Cu(II) atoms are penta-coordinated in the shape of a deformed square pyramid. Four v(CN) absorption bands observed in the IR spectrum are in agreement with the higher number of crystallographically different cyano groups and a broad highly asymmetric band observed in the reflectance UV-Vis spectrum is consistent with the presence of both hexa- and penta-coordinated Cu(II) atoms in the structure. The temperature dependence of the inverse susceptibility suggests the presence of a weak antiferromagnetic exchange coupling between Cu(II) ions. The complex is stable up to 210 °C when its two-stage thermal decomposition starts.     

Synthesis and structures of mono and binuclear nickel(II) thiolate complexes of a dicompartmental pseudo-macrocycle with N(imine)2S2 and N(oxime)2S2 metal-binding sites

The reaction of [Ni(pftp)] [pftp = N,N-propane-1,3-diyl-(6-formyl-4-methyliminatothiophenolato)] with hydroxylamine hydrochloride in the presence potassium acetate in MeOH resulted in the formation of the complex [Ni(LH₂)] [L = N,N-propane-1,3-diyl-(4-methyl-2-methyliminato-6-methyloxime-thiophenolato)] in good yield. A single crystal X-ray diffraction structural determination showed a mononuclear nickel(II) complex with the new acyclic ligand LH₂ that had been functionalised with two oxime groups containing an empty N(oxime)₂S₂ pocket to which another metal ion could be added. A further reaction of [Ni(LH₂)] with NiCl₂·6H₂O, triethylamine and ammonium hexafluorophosphate in MeOH gave a dark red product that yielded red crystals of [Ni₂(LH)]PF₆·DMF via slow recrystallisation from a DMF/PrⁱOH solvent mixture. A single crystal X-ray diffraction study of these crystals confirmed the presence of a dinuclear nickel(II) complex linked by a dithiolato-bridge. Both nickel(II) ions exhibited square-planar geometry where the metal centres are coordinated in two distinct cis-S₂N(imine)₂ and cis-S₂N(oxime)₂ binding sites provided by the new dicompartmental oxime/thiolate-containing ligand LH.     

Synthesis, spectral and magnetical characterization of monomeric [Cu(2-NO2bz)2(nia)2(H2O)2] and structural analysis of similar [Cu(RCOO)2(L-N)2(H2O)2] complexes

A new complex of composition [Cu(2-NO₂bz)₂(nia)₂(H₂O)₂] (1) (nia = nicotinamide, 2-NO₂bz = 2-nitrobenzoate) has been prepared and its composition and stereochemistry as well as coordination mode have been determined by elemental analysis, electronic, infrared and EPR spectroscopy, magnetization measurements over the temperature range 1.8-300 K, and its structure has been solved, as well. The complex structure consists of the centrosymmetric molecules with Cu(II) atom monodentately coordinated by the pair of 2-nitrobenzoato anions and by the pair of nicotinamide molecules, forming nearly tetragonal basal plane, and by a pair of water molecules that complete tetragonal-bipyramidal coordination polyhedron about the copper atom. The complex 1 exhibits magnetic moment μ_eff = 1.86 B.M. at 300 K which decreases to μ_eff = 1.83 B.M. at 1.8 K. The magnetic susceptibility temperature dependence obeys Curie-Weiss law with Curie constant of 0.442 cm³ K mol⁻¹ and with Weiss constant of −1.0 K. EPR spectra at room temperature as well as at 77 K are of axial type with g_⊥ = 2.065 and g_∥ = 2.280 and exhibit clearly, but partially resolved parallel hyperfine splitting with A_II = 160 G, that is consistent with the determined molecular structure of 1. In order to analyze the factors influencing the degree of tetragonal distortion of coordination polyhedron, the dataset of 72 structures similar to that of 1 was extracted from CCD and analyzed. A significant correlation between the average Cu-O_ax bond length and tetragonality parameter τ which was found as a consequence of the Jahn-Teller effect.     

1-D coordination chains of Cu(hfac)2 and Mn(hfac)2 bridged by phenyl-nitronylnitroxide derivatives

Two alternating 1-D metal-radical linear [L:Cu(hfac)₂]_n and zig-zag [L:Mn(hfac)₂]_n chains (where L = 4-trimethylsilylethynyl-1-(4,4,5,5-tetramethyl-3-oxylimidazoline-1-oxide)benzene) and hfac = hexafluoroacetylacetonate) are described and characterized by X-ray diffraction of their crystals. Bulk magnetic measurements of L:Cu(hfac)₂ indicated a ferromagnetic interaction with J = 6 cm⁻¹ and L:Mn(hfac)₂ yielded ferrimagnetic interactions with J = −95 cm⁻¹. For the latter, a strong increase of their magnetic moment at lowest temperatures was observed only at very low static magnetic field, while for H_dc > 0.05 T saturation effect led to a downward slope after reaching a maximum.     

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.     

[Mn2(Fpymo)4(H2O)4]: Synthesis, structure, magnetism and thermally induced solid-to-solid polymerisation reactions

The reaction of an aqueous solution of Mn(ClO₄)₂ · 6H₂O with 5-fluoro-2-hydroxypyrimidine (HFpymo) and NaOH in 1:2:1 ratio affords a species analysing as Mn(Fpymo)₂(H₂O)₂ (1) in 70% yield. Single crystal X-ray analysis reveals that 1 consists of [Mn₂(μ-Fpymo-N¹,O²)₂(Fpymo-O²)₂(H₂O)₄] dinuclear units, in which each Mn(II) ion shows a slightly distorted trigonal bipyramidal stereochemistry. Thermal treatment of 1 above 150 °C gives an anhydrous, amorphous material analysing as Mn(Fpymo)₂ (2a). Further heating of this compound above 250 °C results in the formation of the microcrystalline Mn(Fpymo)₂ species (2b). The thermal dependence of the magnetic susceptibility χ has been studied for species 1 and 2b in the 2-300 K temperature range at 100, 300 and 5000 Oe field strengths. The fitting of the χ values of 1 to the Curie-Weiss equation gives values of C = 2.450(2) and θ = 1.0(2) K, which is indicative of an almost negligible magnetic interaction between the Mn(II) centres. At variance, 2b shows a significant antiferromagnetic behaviour, with a decrease of the μ_eff values upon cooling. The fitting of the χ values of 2b to the Curie-Weiss equation gives the respective C and θ values of 4.26(1) and −14.8(3) K, which agrees with an efficient coupling of the magnetic Mn(II) centres, possibly through bridges of the Fpymo-N¹,N³ kind, within a polymeric network. The N₂ and CO₂ gas adsorption measurements at 77 K and 293 K, respectively, show that the 2b phase is not microporous, which is reflected in its low BET surface (19 m² g⁻¹) and its BJH pore size distribution.     

Cobalt(II) and nickel(II) coordination polymers constructed from P,P′-diphenylmethylenediphosphinic acid (H2pcp) and 4,4′-bipyridine (bipy): Structural isomerism in [Co(pcp)(bipy)0.5(H2O)2]

The P,P′diphenylmethylenediphosphinic acid (H₂pcp) reacts with Co(ClO₄)₂ · 6H₂O and 4,4′-bipyridine to give a mixture of two polymeric isomers of formula [Co(pcp)(bipy)_0.5(H₂O)₂], {red (1) and pink (2)} and the new violet hybrid [Co(Hpcp)₂] (3). The pure red and violet species have been obtained by the reaction of H₂pcp with Co(CH₃COO)₂ · 4H₂O and bipy or with Co(ClO₄)₂ · 6H₂O, respectively. The analogous reaction of Ni(CH₃COO)₂ · 4H₂O or Ni(ClO₄)₂ · 6H₂O with H₂pcp and bipy affords only the [Ni(pcp)(bipy)_0.5(H₂O)₂] species (4). The two cobalt isomers present different structural arrangements. Whereas the red isomer (1) shows an undulated 2D layered structure, the pink one (2) forms an infinite monodimensional strand. Both the architectures extend to higher dimensions through hydrogen bonding interactions. The nickel derivative is isomorphous with the red cobalt isomer. The violet [Co(Hpcp)₂] (3), which is isomorphous with the complexes of the reported series [M(Hpcp)₂], M = Ca(II), Mg(II), presents a monodimensional polymeric structure. Compounds 1 and 4 show a very similar thermal behaviour, the two water molecules being lost in the temperature range 25-150 and 160-320 °C, respectively. Temperature dependent X-ray powder diffractometry (TDXD) has been performed on compound 1 in order to follow the structural transformations that occur during the heating process.     

Ru2(CO)4(OOCR)2L2 sawhorse-type complexes containing axial 5-(4-pyridyl)-10,15,20-triphenylporphyrin ligands

The thermal reaction of Ru₃(CO)₁₂ with various carboxylic acids (benzoic, 4-hydroxyphenylacetic, ferrocenic, stearic, oleic, 4-(octadecyloxy)benzoic) in refluxing tetrahydrofuran, followed by addition of 5-(4-pyridyl)-10,15,20-triphenylporphyrin (L), gives the dinuclear complexes Ru₂(CO)₄(OOCR)₂L₂ (1: R = -C₆H₅, 2: R = -CH₂-p-C₆H₄OH, 3: R = -C₅H₄FeC₅H₅, 4: R = -(CH₂)₁₆CH₃, 5: R = -(CH₂)₇CHCH(CH₂)₇CH₃, 6: R = -p-C₆H₄O(CH₂)₁₇CH₃). Complexes 1-6 were characterised by IR, NMR, and ESI-MS as well as by elemental analysis. The UV-Vis spectra show the Soret band centred at 417 nm and the Q bands at 515, 550, 590 and 645 nm, respectively.     

Sn-S and Ru-Ru bonds cleavage reactions between [Ph3SnS(CH2)3SSnPh3] and Ru3(CO)12: X-ray crystal structures of [Ph3SnS(CH2)3SSnPh3] and trans-[Ru(CO)4(SnPh3)2]

The organotin complex [Ph₃SnS(CH₂)₃SSnPh₃] (1) was synthesized by PdCl₂ catalyzed reaction between Ph₃SnCl and disodium-1,3-propanedithiolate which in turn was prepared from 1,2-propanedithiol and sodium in refluxing THF. Reaction of 1 with Ru₃(CO)₁₂ in refluxing THF affords the mononuclear complex trans-[Ru(CO)₄(SnPh₃)₂] (2) and the dinuclear complex [Ru₂(CO)₆(μ-κ²-SCH₂CH₂CH₂S)] (3) in 20 and 11% yields, respectively, formed by cleavage of Sn-S bond of the ligand and Ru-Ru bonds of the cluster. Treatment of pymSSnPPh₃ (pymS = pyrimidine-2-thiolate) with Ru₃(CO)₁₂ at 55-60 °C also gives 2 in 38% yield. Both 1 and 2 have been characterized by a combination of spectroscopic data and single crystal X-ray diffraction analysis.     

Synthesis, spectroscopy and magnetism of novel metal complexes of 3-aminoflavone (3-af). X-ray crystal structure of 3-af and [Cu(3-af)2(NO3)2]

The synthesis and characterization of four new complexes with the bioactive ligand 3-aminoflavone (3-af) are reported. The complexes of general formula [M(3-af)₂(H₂O)₂](NO₃)₂ · nH₂O], where M = Co(II), Ni(II), and Zn(II), and n = 0, 2, 0, respectively, and [Cu(3-af)₂(NO₃)₂] compound were prepared and studied. In particular, to investigate the binding in detail, the crystal structures of the free ligand (3-af) and [Cu(3-af)₂(NO₃)₂] (1) were determined. The new coordination compounds were identified and characterized by elemental analysis, magnetic measurements, and infrared and ligand-field spectra. The crystal structure of the Cu(II) complex reveals that the ligand acts as a N,O-bidentate chelate ligand forming a five-membered ring with the copper(II) ion. The copper(II) ion is octahedrally surrounded by the two amino nitrogens and two carbonyl oxygens from two chelating organic ligands in trans arrangement. Two molecules of coordinated nitrate anions occupy axial positions. The spectral and magnetic properties are in accordance with the structural data of the copper(II) compound. From X-ray powder-diffraction patterns and IR spectra, the complexes of nickel(II) (2) and cobalt(II) (3) were found to be mutually isomorphous. The results of the spectroscopic studies suggest a mononuclear structure of 2 and 3 complexes. The variable-temperature (1.8-300 K) magnetic susceptibility data of 2 indicate a weak ferromagnetic interaction. The magnetic behavior of complex 3 is characteristic of cobalt(II) systems with an important orbital contribution via spin-orbit-coupling and also suggests a weak ferromagnetic interaction.     

Preparation and structure of [Ru2(O2CMe)4]2[Fe(CN)5NO] and magnetically ordered Hx[Ru2(O2CMe)4]3−x[Cr(CN)5NO] possessing interpenetrating lattices

Reaction of [Ru₂(O₂CMe)₄]Cl with K₃[Cr(CN)₅NO] in water forms H_x[Ru^II/III₂(O₂CMe)₄]_3−x-[Cr(CN)₅NO]·zH₂O (x = 0.2) that magnetically orders at 4.0 K and possesses an interpenetrating body centered cubic [a = 13.2509(2) Å] structure with random locations of the bridging nitrosyl ligands, and x/3 vacant cation sites. Similarly, the aqueous reaction of [Ru₂(O₂CMe)₄]Cl with Na₂[Fe(CN)₅NO] forms paramagnetic [Ru₂(O₂CMe)₄]₂[Fe(CN)₅NO]·H₂O, which has a similar tetragonal interpenetrating structure [a = 13.0186(1) Å, c = 13.0699(2) Å] where the NO ligands are presumably nonbridging and 1/3 of the expected cation sites are unoccupied. The presence of uncoordinated NO sites in addition to missing neighboring [Ru₂(O₂CMe)₄]⁺ units, results in significant vacancies (or holes) in the lattice.     

Synthesis and characterisation of palladium(II) iodo complexes containing water soluble phosphine ligands. Crystal structures of [PdI2(PTA-H)2][PtI3(PTA)]2 · 2H2O and trans-[PdI2(PTA)2]

The aqueous solution behaviour of the equilibrium related cis-[PdCl₂(PTA)₂] and [PdCl(PTA)₃]Cl complexes has been investigated in the presence of acid and iodide ions. Several of the resulting species were identified and a reaction scheme accounting for identified complexes is proposed. The crystal structures of trans-[PdI₂(PTA-H)₂][PdI₃(PTA)]₂ · 2H₂O (1) (PTA-H⁺ = protonated form of PTA) and trans-[PdI₂(PTA)₂] (2) are reported. The geometry around the Pd(II) metal centre in 1 (for both the cation and anion) and 2 is distorted square planar. The PTA ligands occupy a trans orientation in the cation of 1 and in complex 2. Compound 1 represents a rare example of a Pd(II) system wherein the cation:anion pair, in a 1:2 ratio, are both coordination complexes. It is the first d⁸ Ni-triad square planar complex containing only one PTA ligand and only the second platinum group metal complex. For the cation in 1, the bond distances and angles are Pd(1)-P(1) = 2.2864(16) Å, Pd(1)-I(1) = 2.6216(7) Å, P(1)-Pd(1)-P(1)′ = 180.00(7)° and P(1)-Pd(1)-I(1) = 87.62(4)°, while in the anion the bond distances are Pd(2)-P(2) = 2.2377(15) Å, Pd(2)-I(4) = 2.5961(13) Å, Pd(2)-I(2) = 2.6328(13) Å, Pd(2)-I(3) = 2.6513(8) Å, while the angles are P(2)-Pd(2)-I(4) = 90.00(5)°, P(2)-Pd(2)-I(2) = 89.69(5)°, I(4)-Pd(2)-I(2) = 179.57(2)°, P(2)-Pd(2)-I(3) = 175.19(4)°, I(4)-Pd(2)-I(3) = 90.29(4)° and I(2)-Pd(2)-I(3) = 90.05(4)°. Bond distances and angles of the coordination polyhedron in 2 are Pd-P = 2.327(3) Å, Pd-I = 2.5916(10) Å, P-Pd-I = 89.13(7)° and P-Pd-P = 180.00(13)°. The average effective- and Tolman cone angles for the two ligands, calculated from the crystallographic data, are 115° and 117° for PTA and PTA-H, respectively.     

Synthesis of copper-zinc bimetallic imidazolate framework compounds and the structure of Cu(I)-containing Cu2Zn(N2C3H3)4

Copper(II)-zinc(II) bimetallic imidazolate metal-organic framework compounds of composition Cu_aZn_bIm_2(a + b) (Im = C₃H₃N₂), including Cu₂ZnIm₆ (1), were prepared in high yields from the metal oxides under mild aqueous conditions using a novel acid catalysis method. Mild acidic hydrothermal treatment of paramagnetic 1 (≥120 °C) gave diamagnetic Cu(I)-containing Cu₂ZnIm₄ (2) in high yield. The formation mechanism of 2 involves electron transfer from Im⁻ to Cu(II), with concomitant formation of the unusual cyclotriimidazole, C₉H₆N₆. Air-stable 2, characterized by single-crystal X-ray diffraction, crystallized in the tetragonal space group , with a = b = 10.9623(3), c = 6.3231(4) Å, α = β = γ = 90°, V = 759.86(6) Å³, and Z = 1.     

Reaction of Mo(CO)4(NCCH3)2 and 7-aza-2-Tosylnorbornadiene

Reaction of Mo(CO)₄(NCCH₃)₂ and 7-aza-2-tosylnorbornadiene (7-azaNBD) yielded five air-stable Mo complexes. One is Mo(CO)₄(η⁴-7-azaNBD), in which the molybdenum atom is chelated by the two π-bonds of 7-azaNBD. The other four are isomers of Mo(CO)₂(η²-7-azaNBD)₂, in which the molybdenum atoms are chelated by the nitrogen atom and one of the two double bonds of 7-azaNBD. In one pair of the isomers, the metal binds to C(2)C(3) of both 7-azaNBD ligands; whereas in the other pair of isomers the metal binds to C(2)C(3) of one 7-azaNBD ligand and C(5)C(6) of another ligand. All structures were fully characterized by NMR spectra. A single crystal of compound 4 was analyzed by X-ray diffraction analysis, which was found to be monoclinic with a = 8.4199, b = 23.984, c = 16.395 Å, and β = 99.99°.     

The cyanocarbanion (C[C(CN)2]3) as monodentate ligand: Synthesis, structure and magnetic properties of [Mn2(bpym)3(tcpd)2(H2O)2] (tcpd = (C[C(CN)2]3) and bpym = 2,2′-bipyrimidine)

One-pot reaction between MnCl₂·4H₂O, K₂tcpd (tcpd²⁻ = [C₁₀N₆]²⁻ = (C[C(CN)₂]₃)²⁻ = 2-dicyanomethylene-1,1,3,3-tetracyanopropanediide anion) and 2,2′-bipyrimidine (bpym = C₈H₆N₄) in aqueous solution yields the new compound [Mn₂(bpym)₃(tcpd)₂(H₂O)₂] (1). The molecular structure of 1 consists of a centrosymmetrical binuclear complex which includes unprecedented unidentate tcpd ligands with two bidentate and a bis-chelate bpym units. Examination of the intermolecular distances reveals that the dinuclear units are held together by hydrogen bonds involving coordinated water molecules and two nitrile groups of the tcpd ligand, giving rise to a 2D structure overall. Variable-temperature magnetic susceptibility data show the occurrence of slight antiferromagnetic coupling (J = −0.58 cm⁻¹) between the Mn(II) ions through bridging bpym (the exchange Hamiltonian being defined as ).