The formation of a neutral manganese(III) complex containing a tetradentate Schiff base and a ketone – synthesis and characterization

2-Benzoylphenolato-(2,2′-((2,2-dimethylpropane-1,3-diyl)bis((nitrilo)(phenylmethylidyne)))-diphenolato-manganese(III) methanol solvate, [Mn(C₃₁H₂₈N₂O₂)(C₁₃H₉O₂)]·CH₃OH (1), was synthesized and characterized by FTIR, UV–vis, TG-FTIR, TG/DSC, molar conductivity, magnetic moment measurement, and quantum chemical calculations. During the synthesis, partial hydrolysis of ligand is observed. The compound was obtained as amorphous, dark-brown powder. The effects of organic solvents of various polarities on the UV–vis spectra of ligands and complex were investigated. In addition, the IR and UV–vis spectra were also calculated and compared with the experimental data. A single crystal for analysis was obtained by dissolving the amorphous complex in methanol, and slow evaporation of solvent at 4 °C. Single-crystal X-ray analysis indicated that the methanol molecules are not incorporated into the crystal lattice after the recrystallization process ([Mn(C₃₁H₂₈N₂O₂)(C₁₃H₉O₂)] (2)). In the structure Mn(III) is surrounded by two nitrogens and four oxygens of deprotonated Schiff base and α-hydroxy ketone ligands, and adopts a distorted octahedral geometry.     

Synthesis and reactivity of an isolable cobalt(I) complex containing a β-diketiminate-based acyclic tetradentate ligand

A model for cobalamin was synthesized using a new monoanionic tetradentate nitrogen donor ligand; 2-(4-tolyl)-1,3-bis(2-isopropylpyridyl)propenediimine (Tol-BDI((2-pp)2)H) (1), which utilizes isopropylpyridines as pendant arms on a β-diketiminate (BDI) backbone. During the synthesis of 1, the rearrangement product, Tol-BDI((2-pp)(4-pp))H (2) was observed. Metalation of 1 with zinc iodide and cobalt chloride yielded the corresponding Tol-BDI((2-pp)2)ZnI (3) and Tol-BDI((2-pp)2)CoCl (4) complexes. The redox properties of 4 in comparison to cobalamin were examined through electrochemical studies. Electrochemical and bulk reduction of complex 4 gave a diamagnetic cobalt(I) complex, Tol-BDI((2-pp)2)Co (5). Reactivity of 5 toward C-X bonds was investigated using methyl iodide and 1-iodo-2-(trimethylsilyl)acetylene, yielding Tol-BDI((2-pp)2)Co(CH(3))I and Tol-BDI((2-pp)2)Co(C(2)Si(CH(3))(3))I respectively. Synthesis and characterization details for these complexes, including the crystal structure of 3, are reported.     

Structure modulation of metal–organic frameworks via reaction pH: Self-assembly of a new carboxylate containing ligand N-(3-carboxyphenyl)iminodiacetic acid with cadmium(II) and cobalt(II) salts

Self-assembly of a new carboxylate containing ligand, N-(3-carboxyphenyl)iminodiacetic acid (H₃L), with Cd(II) and Co(II) salts under different reaction pH results in the formation of four new coordination polymers, namely [Cd(HL)(H₂O)] (1), [Co(HL)(H₂O)] (2), [Cd(HL)(H₂O)₄] (3) and [Cd₃(L)₂(H₂O)₉] · 7H₂O (4). Single crystal X-ray diffraction analysis indicates that 1 and 2 are isomorphous and isostructural with a 2D wave-like network structure, while 3 has a 1D zigzag chain structure. The complexes 1–3 were obtained at low pH (<7) which makes the ligands only partly deprotonated. However, complex 4, obtained at pH 7 with all the carboxylate groups deprotonated, exhibits a 2D network structure. The results suggest that the reaction pH is one of the key factors in the formation of the coordination architectures. In addition, the photoluminescence properties of the free ligand (H₃L) and complexes 1, 3 and 4 were studied in the solid state at room temperature. Moreover, the magnetic property of complex 2 was investigated.     

Synthesis, characterization, and reactivity of a novel μ-η2:η2-diselenidodicopper(II) complex

The first μ-η(2):η(2)-diselenidodicopper(II) complex has been obtained in the reaction of a copper(I) complex with N,N',N″-tribenzyl-cis,cis-1,3,5-triaminocyclohexane and elemental selenium. The structure and reactivity of the complex is described.     

Synthesis,characterization and reactivity of pentacarbonyl(η1-2,4-pentadienyl)manganese

Reaction of NaMn(CO)₅ with trans-1-bromopenta-2,4-diene in tetrahydrofuran at −78°C gives (η¹-2,4-pentadienyl)Mn(CO)₅ (1) in excellent yield. Compound 1 undergoes η¹ → syn-η³ → η⁵ transformation and, yields (syn-η³-2,4-pentadienyl)Mn)(CO)₄ (2) and (η⁵-pentadienyl)Mn(CO)₃ (3), respectively. The reactions of 1 with the electrophiles tetracyanoethylene (TCNE) and sulfur dioxide (SO₂) were investigated. Compound 1 undergoes a [4 + 2] cycloaddition with TCNE and an insertion reaction with SO₂. The product are characterized by elemental analysis and spectroscopic data.     

Synthesis, characterization, and norbornene polymerization of η-benzylnickel(II) complexes of N-heterocyclic carbenes

Neutral η¹-benzylnickel carbene complexes, [Ni(η¹-CH₂C₆H₅)(IiPr)(PMe₃)(Cl)] (3) (IiPr = 1,3-bis-(2,6-diisopropylphenyl)imidazol-2-ylidene) and [Ni(η¹-CH₂C₆H₅)(SIiPr)(PMe₃)(Cl)] (4) (SIiPr = 1,3-bis-(2,6-diisopropylphenyl)imidazolin-2-ylidene), were prepared by the reaction between [Ni(η³-CH₂C₆H₅)(PMe₃)(Cl)] and an equivalent amount of the corresponding free N-heterocyclic carbene. The preparation of η³-benzylnickel carbene complexes, [Ni(η³-CH₂C₆H₅)(IiPr)(Cl)] (5) and [Ni(η³-CH₂C₆H₅)(SIiPr)(Cl)] (6) were carried out by the abstraction of PMe₃ from 3 and 4 by the treatment of B(C₆F₅)₃. The treatment of AgX on 5 and 6 produced the anion-exchanged complexes, [Ni(η³-CH₂C₆H₅)(NHC)(X)] (7, NHC = IiPr, X = O₂CCF₃; 8, NHC = IiPr, X = O₃SCF₃; 9, NHC = SIiPr, X = O₂CCF₃; 10, NHC = SIiPr, X = O₃SCF₃). The solid state structures of 3 and 10 were determined by X-ray crystallography. The η³-benzyl complexes of IiPr (5, 7, and 8) alone, in the absence of any activators such as borate and MAO, showed good catalytic activity towards the vinyl-type norbornene polymerization. The catalyst was thermally robust and the activity increases as the temperature rises to 130 °C.     

Synthesis,structure and magnetism of a hydrogen-bond-linked three-dimensional network of a novel nickel(II)–cobalt(II)–nickel(II) complex containing a new macrocyclic mononuclear complex ligand

A novel trinuclear complex, [Co(NiL)₂(H₂O)₂](ClO₄)₂ · 2C₂H₅OH, was prepared by self-assembly using [NiL] as a new complex ligand; L is the dianion of dimethyl 5,6,7,8,15,16-hexahydro-6,7-dioxodibenzo[1,4,8,11]tetraazacyclotetradecine-13,18-dicarboxylate. The structure of the trinuclear complex was determined by X-ray crystallography. The Co^II ion is at the center of the trinuclear complex cation and occupies a distorted octahedral O₆ environment, approximating to O _h with a ⁴ T _1g ground state for Co^II that has an unquenched spin–orbit coupling reflected in the magnetic properties. Two Ni^II ions reside in completely same and slightly distorted square-planar N₄ coordination geometries. Co^II and each Ni^II are bridged by an oxamido group from one of the two macrocyclic ligands (L). O—H...O and ... interactions link the trinuclear fragments, perchlorate ions and C₂H₅OH molecules to form a three-dimensional supramolecular architecture.     

Synthesis,characterization and DFT aspects of some oxovanadium(IV) and manganese(II) complexes involving dehydroacetic acid and β-diketones

Six new mixed-ligand oxovanadium(IV) and manganese(II) complexes of the general composition [VO(dhaH)(L¹H)(L²)] and [Mn(dhaH)(L¹H)(L²)], where dhaH=dehydroacetic acid, L¹H=β-ketoenolates viz., acetoacetanilide (aaaH), o-acetoacetotoluidide (o-aatdH), o-acetoacetanisidide (o-aansH) and L²=benzimidazole (bzl), 3-methyl-1phenyl-2pyrazoline-5one (mphp), 2-aminobenzimidazole (abzl) or 2-aminobenzathiozole (abtz) have been synthesized. The resultant complexes were characterized on the basis of elemental analysis, molar conductance, magnetic measurements, mass spectrometry, thermogravimetric analysis, infrared and electron spin resonance studies. The thermal decomposition processes of one representative of the complexes are discussed and the order of reaction (n), the activation energies (E_a), the pre-exponential factor (A), have been calculated from thermogravimetric (TG) and differential thermogravimetric (DTG) curves. Gaussian 09 software package was used to carry out theoretical computation using density functional theory (DFT) methods with Becke3-Lee-Yang-Parr (B3LYP) hybrid exchange-correlation functional and the standard LANL2 MB basis set. Based on combined experimental-theoretical characterization, a suitable octahedral structure has been proposed for this class of complexes.     

New metal–organic architectures of cobalt(II), nickel(II) and zinc(II) with tripodal ligand 5-(1H-imidazol-4-ylmethyl)aminoisophthalic acid

Four new coordination polymers {[Ni(HL)(H₂O)]·H₂O}_n (1), {[Co(HL)(H₂O)]·H₂O}_n (2), {[Co(HL)]·4H₂O}_n (3) and {[Zn(HL)]·2H₂O·0.5C₂H₅OH}_n (4) [H₃L = 5-(1H-imidazol-4-ylmethyl)aminoisophthalic acid] have been synthesized under hydrothermal conditions and characterized by single-crystal X-ray diffraction analyses. Complexes 1 and 2 display (3, 3)-connected 2D network with (4, 8²) topology. While 3 and 4 exhibit a binodal (3, 6)-connected 2D network with a Schläfli symbol (4³)₂(4⁶, 6⁶, 8³). The complexes 1–4 show remarkable thermal stability and 4 exhibits blue fluorescence with maximum emission at 413 nm upon excitation at 362 nm in the solid state at room temperature. In addition, the magnetic measurements of 3 indicate that there are antiferromagnetic interactions between the neighboring Co(II) centers.     

On the isomerization of cyclooctyne into cycloocta-1,3-diene: synthesis, characterization and structure of a dinuclear platinum(II) complex with a μ-η2:η2-1,3-COD ligand

The Zeise's salt type cyclooctyne compound [K(18C6)][PtCl(3)(COC)] (1; COC = cyclooctyne; 18C6 = 18-crown-6) was found to react in chloroform solution at room temperature within several weeks yielding the dinuclear cyclooctadiene compound [K(18C6)](2)[(PtCl(3))(2)(μ-η(2):η(2)-1,3-COD)] (2; 1,3-COD = cycloocta-1,3-diene) and non-coordinated cycloocta-1,3-diene. The identity of 2 was confirmed by microanalysis, NMR spectroscopy ((1)H, (13)C) and electrospray ionization mass spectrometry (ESI-MS). A single-crystal X-ray diffraction analysis of 2 exhibited a bridging μ-η(2):η(2)-cycloocta-1,3-diene ligand with non-conjugated double bonds each coordinated to a PtCl(3) fragment. On the basis of DFT calculations as well as energy decomposition analyses (EDA), charge decomposition analyses (CDA) and natural bond orbital (NBO) analyses the peculiarities of the nature of the Pt-C bonds in the dinuclear complex anion [(PtCl(3))(2)(μ-η(2):η(2)-1,3-COD)](2-) (2a') compared with those in mononuclear olefin complexes of Zeise's salt type [PtCl(3)L](-) (L = η(2)-1,3-COD, 3a'; cis-but-2-ene, 4a'; COE, 5a'; COE = cyclooctene) are discussed. Furthermore, the driving force for the strongly exergonic reaction with formation of the cyclooctadiene complex 2a' was found to be a significant release of ring strain of the cyclooctyne ligand in the starting compound 1.     

A photoluminescent dinuclear phenylquinolyl Ir(II)-Ir(II) complex featuring a μ-η1:η2-phenylquinolyl bridge and an end-on dinitrogen ligand

The synthesis, characterization and photoluminescent properties of a dinuclear Ir complex with a μ-η(1):η(2)-phenylquinolyl bridge and an end-on dinitrogen ligand are reported herein. DFT studies on its electronic structure and photophysical properties are also presented.     

Synthesis, characterization and crystal structures of manganese (Ⅱ) complexes containing nitronyl nitroxide and its reduced derivative

Two novel adducts of formula Mn(hfac)2( NITPhCl )2 (1) and [Mn(hfac)2(IMHPhCl)]2(NIT-PhCl)·0.5H2O (2), where hfac = hexafluoroacetylacetonate, NITPhCl = 2-(3-chlorophenyl)-4,4,5,5-tetram-ethylimidazolyl-1-oxyl-3-oxide, IMHPhCl = 2-(3-chlorophenyl)-4, 4, 5, 5-tetramethylimidazolyl-3-oxide, have been prepared by the reaction of Mn(hfac)2·2H2O with NITPhCl. Compound 1 is triclinic, space group P-1with a = 1.3003(3) nm, 6 = 1.3138(3) nm,c = 1.4931 (3) nm, α = 83.74(3)°, β = 77.77(3)°, γ = 60.59(3)°, V=2.171(1)nm3, Z = 2. Compound 2 is triclinic, space group P-1 with a = 1.2994(3) nm, b = 1.4841(3) nm, c = 2.1031 (4) nm, a = 92.30(3)° ,p = 98.68(3)°, γ = 97.89(3)°, V= 3.964(2)nm3, Z = 2. Each manganese atom is hexacoordinated in both compounds and compound 2 is organized inchains by hydrogen bonds between neighboring pairs of NITPhCl and IMHPhCl.     

Synthesis,characterization, luminescent,and catalytic performance of a dinuclear triazenido–silver complex

Our group has developed a series of molecular electrocatalysts for hydrogen generation based on triazenido–metal complexes (such as cobalt, copper, etc.). In this paper, we present the electrocatalytic performance of a new dinuclear silver complex, [Ag₂(L)₂], formed by reaction of the triazenido ligand, 1-[(2-carboxyethyl)benzene]-3-[benzimidazole]triazene (HL) with AgNO₃. The electrocatalytic systems based on this silver complex can afford 91.23 and 473 moles of hydrogen per mole of catalyst per hour (mol H₂/mol catalyst/h) from acetic acid at overpotential (OP) of 991.6 mV and an aqueous buffer at an OP of 837.6 mV, respectively. Electrochemical investigations show both the silver center and the triazenido ligand, HL, play important roles in determining the catalytic activities of the electrocatalytic system. Additionally, the triazenido ligand (HL) can serve as a fluorescent sensor for Ag⁺.     

Synthesis and crystal structure of dinuclear nickel (Ⅱ) complex

The crystal structure of Ni(Ⅱ) complex with 3-hydroxyl-1, 5-diazacycloheptane-N, N'-diacetate was determined by X-ray diffraction method. Crystal data for Ni2 (C9H14N2O5)2·2H2O: monoclinic, space group P21/n, a = 1.1717(5), b = 0.9794(3), c = 1.2971(2) nm, β= 96.62(3), V= 1.4786(7) nm3, Dc = 1.377 g/cm3, Z = 2,μ=13.321 cm-1 (Mo-Kα), F(000)=640. The final R and Rw are 0.075 and 0.089 respectively. The Ni(Ⅱ) ion forms 2:2 complex with ligand. Two ligands are bridged by two Ni(Ⅱ) atoms which are bridged by two O atoms. Every Ni(Ⅱ) is coordinated by two N atoms and four 0 atoms. The coordination polyhedron of the Ni(Ⅱ) ion is a distorted octahedron.     

Synthesis,characterization, and reactivity of ruthenium(II) complexes containing η6-arene-η1-pyrazole ligands

New ruthenium(II) complexes containing η⁶-arene-η¹-pyrazole ligands were synthesized and characterized by elemental analysis and spectroscopic methods. In addition, the molecular structure of dichloro-3,5-dimethyl-1-(pentamethylbenzyl)-pyrazole–ruthenium(II), [Ru]L_3b, was determined by X-ray diffraction studies. These complexes were applied in the transfer hydrogenation of acetophenone by isopropanol in the presence of potassium hydroxide. The activities of the catalysts were monitored by NMR.     

Three new dinuclear bis-μ-azido-bridged Cu(II) compounds with di-2-pyridylamine as a ligand: Syntheses,X-ray structure and magnetic measurements

Three new dinuclear copper(II) compounds: [Cu₂(dpyam)₂(μ_1,1-N₃)₂(O₂CH)₂] (1), [Cu₂(dpyam)₂(μ_1,1-N₃)₂(O₂CCH₃)₂] (2) and [Cu₂(dpyam)₂(μ_1,1-N₃)₂(O₂CCH₂CH₃)₂] (3) have been synthesized and characterized crystallographically and spectroscopically. Compounds 1, 2 and 3 consist of a dinuclear unit in which both Cu(II) ions are connected through two end-on azido bridges providing a distorted square pyramidal geometry with a CuN₄O chromophore. The Cu?Cu separations are 3.195, 3.200 and 3.247 Å for compounds 1, 2 and 3, respectively. The magnetic properties have been measured in the range from 5 to 300 K and correlated with the molecular structures. All three compounds show a medium to weak ferromagnetic exchange interactions between the Cu(II) ions dominated by the bridging azido ligands, with a singlet-triplet splitting (J) of 63.3, 63.8 and 5.1 cm⁻¹, for compounds 1, 2 and 3, respectively. A large zero-field splitting of about 0.4 cm⁻¹ is observed in the EPR for compounds 1 and 2.     

Synthesis and characterization of a tetranuclear copper(Ⅱ) complex with a chiral Schiff base ligand

The title complex l-[Cu^Ⅱ₄（Hvap）₂（vap）₂（MeOH）₂]（CIO₄）₂ 1 has been synthesized and characterized by EA. IR,TGA,solid-state CD spectra and X-ray single-crystal analyses（l-H₂vap’.a Schiff base ligand derived from the condensation of o-vanillin and l-2-amino-3-phenyl-l-propanol）.Complex 1 crystallizes in monoclinic system,chiral space group P2₁ with a =10.4257（18）.b = 21.695（4）,c = 15.721（3）A,β= 94.443（3）.V= 3545.1（11） ³,Z=2,Cu₄C₇₀H₇₈N₄O₂₂Cl₂.Mr= 1652.42,D_c= 1.548 g/cm³, F（000）= 1704 andμ（MoKα） = 1.338 mm^-1.The final R = 0.0682 and wR = 0.1420 for 6170 observed reflections with I > 2σ（I） and R = 0.1775 and wR = 0.1830 for all data.The structure of complex 1 contains a boat-shaped(Cu₄O₄} motif.The solid-state CD spectra confirm the chiral nature of complex 1.     

Syntheses, structures, and reactivity of ruthenium(II) hydride complexes containing Kläui’s oxygen tripodal ligand

Treatment of Ru(CO)(Cl)(H)(PPh₃)₃ with NaL_OEt (L_OEt ^? = [CpCo{P(O)(OEt)₂}₃]^?) afforded the hydride complex (PPh₃)(CO)-L_OEtRu(H) (1), which has been characterized by X-ray crystallography. Similarly, the tricyclohexylphosphine analogue, (PCy₃)(CO)L_OEtRu(H) (2), was synthesized from Ru(CO)Cl(H)(PCy₃)₂ and NaL_OEt. Treatment of complex 1 with R’sO₂N₃ afforded the (arylsulfonyl)amido complexes L_OEtRu(CO)(PPh₃)(NHSO₂R) (R = 2,4,6-i-Pr₃C₆H₂ (3), 4-t-BuC₆H₄ (4)). The crystal structure of complex 3 has been determined. The Ru-N distance and Ru-N-S angle in 3 are 2.076(3) Å and 126.14(16)°, respectively. Reactions of complex 1 with acids have been studied.     

Synthesis and characterization of yttrium,europium, terbium and dysprosium complexes containing a novel type of triazolyl–oxazoline ligand

We report the synthesis of a novel type of bidentate chiral ligand which structurally derives from the association of a 1,2,3-triazole ring with a chiral oxazoline. Yttrium and lanthanide nitrato-complexes of the new triazolyl–oxazoline ligand were prepared and characterized. The coordination mode of the ligand was ascertained by means of DFT calculations. Trivalent europium and terbium derivatives resulted appreciably photoluminescent upon excitation with UV light, showing the typical ⁵D₀ → ⁷F_J and ⁵D₄ → ⁷F_J emissions, respectively. These species were successfully used for the preparation of luminescent-doped polymeric materials.