Thio-azo proligands based on 5,6-derivatives-1,10-phenanthroline and their use for iron(II) complexes: Synthesis,characterization and crystal structures

The preparation and characterization of 5,6-substituted-1,10-phenanthrolines, phdtos = 5,6-bistosyl-1,10-phenanthroline (1) and phdbt = 5,6-dibenzyltiol-1,10-phenanthroline (2) are described. The synthesis of (1) was achieved in good yield via the corresponding dihydroxide and 2 was obtained by cross-coupling reaction of 5,6-dibromo-1,10-phenanthroline and benzylthiol mediated by a palladium catalytic system in refluxing toluene (120 °C). These phenanthroline derivatives were used as ligands to afford [Fe^II(phdtos)₃](PF₆)₂ (5) and [Fe^II(phdbt)₃](PF₆)₂ (6) complexes.     

Ferrocene bridged and substituted tetramethylcyclopentadienyl (or indenyl) carbonyl complexes of iron, ruthenium, and molybdenum

Reactions of ferrocene bridged and substituted tetramethylcyclopentadiene ligands 1,1′-Fc(C₅Me₄H)₂ (1) (Fc = 1,1′-ferrocenediyl) and (C₅H₅FeC₅H₄)C₅Me₄H (5) with Ru₃(CO)₁₂, Fe(CO)₅, and Mo(CO)₃(CH₃CN)₃ in refluxing xylene gave the corresponding trinuclear and tetranuclear complexes Fc[(C₅Me₄)M(CO)]₂(μ-CO)]₂ [M = Ru (2), Fe (3)], Fc[(C₅Me₄)Mo(CO)₃]₂ (4) and [(C₅H₅ FeC₅H₄)C₅Me₄M(CO)]₂(μ-CO)₂ [M = Ru (6), Fe (7)], [(C₅H₅FeC₅H₄)C₅Me₄Mo(CO)₃]₂ (8). Reactions of (3-indenyl)ferrocene (9) with Ru₃(CO)₁₂ or Fe(CO)₅ in refluxing xylene or heptane, also gave the corresponding tetranuclear metal complexes [(C₅H₅FeC₅H₄)C₉H₆M(CO)]₂(μ-CO)₂ [M = Ru (10), Fe (11)]. The molecular structures of 2 and 3 were determined by X-ray diffraction analysis.     

Synthesis and crystal structures of Group 6 metal carbonyl complexes containing S-rich bis(pyrazol-1-yl)methane ligands

The reaction of 3(5)-methylthio-5(3)-phenylpyrazole with dibromomethane under phase-transfer catalytic conditions only affords a new ligand, bis(3-phenyl-5-methylthiopyrazol-1-yl)methane. However, the reaction of 3(5)-methylthio-5(3)-p-methoxyphenylpyrazole or 3(5)-methylthio-5(3)-tert-butylpyrazole with dibromomethane under the same conditions yields three isomers, respectively, indicating that the substituents significantly affect the steric and electronic properties of pyrazole ring during the formation of ligands. Treatment of these potential polydentate ligands with M(CO)₆ (M=Cr, Mo or W) under UV irradiation at room temperature affords (NN)M(CO)₄ derivatives, in which some complexes contain asymmetric substituted bis(pyrazol-1-yl)methane ligands. The X-ray crystal structure analyses indicate that the sulfur atoms in these complexes do not take part in the coordination to the metal centers, and S-rich bis(pyrazol-1-yl)methanes actually act as bidentate chelating ligands by two nitrogen atoms. It is also interesting that in order to reduce the repulsion of methyl groups with carbonyls, the methyl groups in these complexes are oriented away from the metal centers.     

Tertiary phosphine induced migratory carbonyl insertion in cyclopentadienyl complexes of iron(II)

Cyclopentadienyldicarbonylmethyliron, [CpFe(CO)₂Me] (1), undergoes migratory carbonyl insertion under the influence of isosteric phosphine ligands P(4-FC₆H₄)₃ and P(4-MeC₆H₄)₃. The products of the reaction, [CpFe(CO)(COMe)P(4-FC₆H₄)₃] (2a) and [CpFe(CO)(COMe)P(4-MeC₆H₄)₃] (2b), were characterised by X-ray crystallography. In both structures, the iron atom adopts a pseudo octahedral coordination geometry. Fe-P bond distances are the same at 2.1932(8) Å in 2a and 2b, respectively. Thus, contrary to what was expected, X-ray data could not be used to quantitatively differentiate between the two phosphine ligands in 2a and 2b. Therefore, additional spectroscopic techniques such as IR and NMR were employed. Similarly, the Fe-C bond lengths of the carbonyl (Fe-CO) and acetyl (Fe-COMe) are 1.748(3) and 1.955(3) in 2a, and 1.744(3) and 1.951(3) Å in 2b, respectively.The migratory carbonyl insertion was studied by NMR, IR, and UV-vis spectroscopies to determine the mechanism and the rate law. Results from NMR spectroscopy show that the formation of the product is accompanied by oxidation of the corresponding phosphine ligand. An increase in the reactivity of migratory carbonyl insertion for P(4-MeC₆H₄)₃ was observed when the solvent was changed from CH₂Cl₂ to MeCN. The kinetic data showed that P(4-MeC₆H₄)₃ reacts faster than P(4-FC₆H₄)₃.     

Mononuclear and dinuclear iron thiocyanate and selenocyanate complexes of tris-pyrazolylmethane ligands

Treatment of Fe(NCE)₂ (E = S or Se) with 1 equiv. of tris-(3,5-dimethylpyrazol-1-yl)methane (tpm′) yields dimeric [{Fe(NCE)(μ-NCE)(tpm′)}₂]. These dimers are cleaved in MeCN solution, yielding isolable [Fe(NCE)₂(tpm′)(NCMe)], whose solvent ligands can be substituted by moderately basic heterocycle donors to give [Fe(NCE)₂(tpm′)(py)], [Fe(NCS)₂(tpm′)(im)] or [{Fe(NCE)₂(tpm′)}₂(μ-4,4′-bipy)]. The monodentate heterocycles in the latter compounds are readily lost in most solvents, regenerating the dimeric starting materials. [Fe(NCS)₂(tpm′)(py)] was also prepared by reacting [Fe(NCS)₂(py)₄] with tpm′. The mononuclear compounds are all high-spin between 5 and 300 K, despite mostly having regular coordination geometries and tpm′ ligand conformations that should in principal favour spin-crossover. Analogous products containing unsubstituted tris-(pyrazol-1-yl)methane (tpm) could not be isolated, but the crystal structure of the double salt [Fe(tpm)₂][Fe(NCS)₅(py)], containing a new iron(III) anion, is described.     

Two dinuclear copper(II) complexes based on 5,6-dimethylbenzimidazole ligands: synthesis, crystal structures, and catalytic properties

Two new dinuclear copper(II) complexes, Cu₂(L1)₄(mal)₂(H₂O)₂ (1) (L1 = 5,6-dimethylbenzimidazole, mal = malonate), Cu₂(L2)₂(pydca)₂·4H₂O (2) (L2 = 1,5-bis(5,6-dimethylbenzimidazole)pentane, pydca = pyridine-2,6-dicarboxylate) have been synthesized and characterized by elemental analysis, IR, and single-crystal X-ray diffraction. The Cu(II) atoms in 1 and 2 both have square pyramidal coordination geometry. In 1, the two similar mononuclear structures are linked by π–π stacking as well as multiple hydrogen bonding interactions to generate a 2D supramolecular layer, while complex 2 is connected with two different patterns of π–π stacking and hydrogen bonding interactions into a 3D supramolecular network. The catalytic activities of 1 and 2 for the degradation of Congo red have been investigated.     

α,β-Unsaturated diimines as substrates in catalytic C-H activation reactions and as ligands in iron carbonyl complexes

The reaction of 3-[4-(3-oxo-propenyl)-phenyl]-propenal with two equivalents cyclohexylamine as well as the treatment of cyclohexane-1,4-diamine or bis-(4-aminocyclohexyl)-methane with two equivalents of cinnamaldehyde leads to the formation of the corresponding diimines. Mono- or dinuclear iron carbonyl complexes are produced if the diimines are reacted with iron carbonyls. Two of these complexes have been characterized by X-ray crystallography showing that one or two of the α,β-unsaturated imine side chains are coordinated by an iron tricarbonyl moiety in a η⁴-fashion. The packing is realized by intermolecular C-H?O contacts. The same diimines are used as the substrates in ruthenium catalyzed C-H activation reactions together with carbon monoxide and ethylene to produce bis-dihydropyrrolone derivatives in almost quantitative yields.     

Synthesis and characterization of chiral iron carbonyl complexes from imine ligands with carbohydrates and amino acids as substituents

Imine ligands derived from 6-amino-6-desoxy-1,2,3-O-trimethyl--d-glucopyranose or from various amino acid esters react with Fe₂(CO)₉ to give chiral iron carbonyl complexes. Derivatives produced from benzaldehyde react via a C–H activation reaction in ortho-position with respect to the exocyclic imine substituent followed by an intramolecular hydrogen transfer reaction of the activated hydrogen towards the former imine carbon atom. The molecular structure of the diiron hexacarbonyl complexes of benzylideneamino-l-phenylalanine ethyl ester and benzylideneamino-l-methionine methyl ester were characterized by means of X-ray structure determinations. Imines produced from cinnamaldehyde upon reaction with Fe₂(CO)₉ produce mononuclear iron tricarbonyl complexes with the imine ligand being coordinated in a η⁴-fashion.     

Synthesis,crystal structures,and magnetic properties of methoxido-bridged dinuclear MnIII complexes derived from tri-dentate chelating ligands

Two new doubly methoxido-bridged Mn^III dinuclear complexes, [Mn^III(mphp)(μ-OCH₃)(CH₃OH)]₂·2CH₃OH (1) and ([Mn^III(ahbz)(μ-OCH₃)(CH₃OH)]₂·2CH₃OH (2), have been synthesized by using the tridentate ligands H₂mphp (H₂mphp = 2-methyl-6-(pyrimidin-2-yl-hydrazonomethyl)-phenol) and H₂ahbz (H₂ahbz = N-(2-amino-propyl)-2-hydroxy-benzamide). The complexes have been characterized by single-crystal X-ray diffraction analysis and magnetic measurements. Complexes 1 and 2 have a similar dimeric molecular structure. Two [Mn(L)(CH₃OH)]⁺ moieties (L^2? = mphp^2? or ahbz^2?) are bridged by two μ-OCH₃^? groups in the axial-equatorial asymmetric manner. The coordination geometry of Mn^III is an axially elongated octahedron with two oxygens of a methanol ligand and a methoxido ligand situated at the axial positions. Magnetic measurements indicate that 1 and 2 exhibit antiferromagnetic behavior with the fitting parameter of J = ?1.49(3) cm^?1, D = ?1.3(1) cm^?1, g = 1.98(1) and zJ′ = ?0.18(4) cm^?1 for 1, and J = ?1.6(2) cm^?1, D = 4.5(3) cm^?1, g = 2.06(1) and zJ′ = 1.4(1) cm^?1 for 2 on the basis of the spin Hamiltonian ? = ?2J?_Mn1?_Mn2.     

Synthetic and structural studies of the diiron toluenedithiolate carbonyl complexes with monophosphine ligands

Four diiron toluenedithiolate complexes 2–5 with monophosphine ligands are reported. Treatment of [μ-SC₆H₃(CH₃)S-μ]Fe₂(CO)₆ (1) with tris(3-chlorophenyl)phosphine, tris(4-chlorophenyl)phosphine, tris(4-methylphenyl)phosphine or 2-(diphenylphosphino)benzaldehyde, and Me₃NO?2H₂O in MeCN resulted in the formation of [μ-SC₆H₃(CH₃)S-μ]Fe₂(CO)₅[P(3-C₆H₄Cl)₃] (2), [μ-SC₆H₃(CH₃)S-μ]Fe₂(CO)₅[P(4-C₆H₄Cl)₃] (3), [μ-SC₆H₃(CH₃)S-μ]Fe₂(CO)₅[P(4-C₆H₄CH₃)₃] (4), and [μ-SC₆H₃(CH₃)S-μ]Fe₂(CO)₅[Ph₂P(2-C₆H₄CHO)] (5) in 64–82% yields. Complexes 2–5 have been characterized by elemental analysis, IR, ¹H NMR, ³¹P{¹H} NMR, ¹³C{¹H} NMR and further confirmed by single crystal X-ray diffraction analysis. The molecular structures show that 2–5 contain a butterfly diiron toluenedithiolate cluster coordinated by five terminal carbonyls and an apical monophosphine.     

Synthesis and characterization of tungsten carbonyl complexes containing N-methyl substituted urea and thiourea ligands

Six new mixed-ligand tungsten carbonyl complexes containing N-methyl substituted urea and thiourea of the type W(CO)₄[RCH₂N-(C=X)NH₂] where X?=?O or S and R?=?morpholine, piperidine and diphenylamine are reported. These have been prepared by refluxing hexacarbonyl tungsten(0) with corresponding ligands in THF to produce cis-disubstituted products, [(L-L)W(CO)₄] where L-L?=?a chelating bidentate ligand, morpholinomethyl urea (MMU), morpholinomethyl thiourea (MMTU), piperidinomethyl urea (PMU), piperidinomethyl thiourea (PMTU), diphenylaminomethyl urea (DAMU) and diphenylaminomethyl thiourea (DAMTU). The compounds have been characterized by elemental analysis, IR, electronic and ¹³C NMR spectra, magnetic moments and conductivity measurements. The IR spectra suggests that in all the complexes, the ligands are bidentate chelating, coordinating the metal through carbonyl oxygen or thiocarbonyl sulphur and the ring nitrogen or tert-nitrogen of diphenylamine. The CO force constants and CO–CO interaction constants for these derivatives have also been calculated using Cotton–Kraihanzel secular equations, which indicate poor π-bonding ability of the ligands. ¹³C NMR and electronic spectra reveal loss of cis-carbonyl ligands to produce cis-disubstituted tetracarbonyl derivatives. Molecular modeling studies have been carried out using Hyperchem release 7.52 which suggest a distorted octahedral geometry for these complexes.     

Syntheses,structures and catalytic activity for Friedel-Crafts reactions of substituted indenyl rhenium carbonyl complexes

The complexes [(η⁵-C₉H₆R)Re(CO)₃] [R = ⁿBu (8), ^tBu (9), CH(CH₂)₄ (10), Ph (11), Bz (12), 4-methoxyphenyl (13), 4-chlorophenyl (14)] were synthesized by refluxing substituted indenyl ligands [C₉H₇R] [R = ⁿBu (1), ^tBu (2), CH(CH₂)₄ (3), Ph (4), Bz (5), 4-methoxyphenyl (6), 4-chlorophenyl (7)], and Re₂(CO)₁₀ in decalin. The molecular structures of 9, 10, 12, and 13 were determined by X-ray diffraction analysis. These four crystals have similar molecular structures of the mononuclear carbonyl complex. In each of these molecules, Re is η⁵-coordinated to the five-membered ring of the indenyl group. Complexes 8–14 have catalytic activity for Friedel-Crafts reactions of aromatic compounds with a variety of alkylation and acylation reagents. Compared with traditional catalysts, these mononuclear metal carbonyl complexes have obvious advantages such as high activities, mild reaction conditions, high selectivity, and environmentally friendly chemistry.     

Synthesis,characterizations and crystal structures of new antimony (III) complexes with dithiocarbamate ligands

Eight new antimony (III) complexes containing dithiocarbamate ligands (R₂NCS₂)₂SbBr [R₂NCS₂ = OC₄H₈NCS₂ (1), C₂H₅NC₄H₈NCS₂ (2), Me₂NCS₂ (3), C₄H₈NCS₂ (4)] and (R₂NCS₂)₃Sb[R₂NCS₂ = C₅H₁₀NCS₂ (5), Bz₂NCS₂ (6), Et₂NCS₂ (7), (HOCH₂CH₂)₂NCS₂ (8)] have been synthesized by the reactions of antimony (III) halides with dithiocarbamate ligands in 1:2 or 1:3 stoichiometries. All the complexes have been characterized by elemental analysis, melting point as well as spectral [IR and NMR (¹H and ¹³C)] studies. The crystal structures of complexes 1, 5 and 8 have been determined by X-ray single crystal diffraction, and their electrochemical character has also been studied.     

Dioxomolybdenum(VI) complexes of hydrazones of two substituted salicylaldehydes: synthesis,structures, and catalytic properties

Dioxomolybdenum(VI) complexes [MoO₂L(CH₃OH)] (L?=?L¹?=?N′-(2-hydroxy-5nitrobenzylidene)isonicotinoylhydrazide for 1, L?=?L²?=?N′-(4-diethylamino-2-hydroxybenzylidene)-4-methylbenzohydrazide for 2) were prepared and structurally characterized by physicochemical and spectroscopic methods and single-crystal X-ray determination. Mo in the complexes is octahedrally coordinated. Both complexes show effective catalysis in oxidation of cyclohexene, vinylbenzene, 1-butylene, and 1-pentene, to their corresponding epoxides. In general, high epoxide yields (over 89%) and selectivity (100%) were observed for all aliphatic and aromatic substrates.     

Synthesis, properties and crystal structures of ferrocene derivatives containing pyrazinium and quinoxalinium units

The pyrazinium salt [FcCH₂pyz][BF₄] (1) and the quinoxalinium salt [FcCH₂quin][BF₄] (2) were prepared by the reaction of [FcCH₂][BF₄] with pyrazine and quinoxaline, respectively and characterised by spectroscopic methods, cyclic voltammetry and by single-crystal X-ray diffraction, which revealed the absence of any π-π-stacking motifs in the crystal structures.     

含硫氮杂环卡宾铁羰基簇合物的合成和结构

Fe~3(CO)~1~2与4个S,N取代的杂环硫代酰胺配前体[SCSC(SR)NNPh(SL~n),其中SL~1:R=Me;SL~2:R=Et;SL~3:R=n-Pr;SL~4:R=i-Bu]反应,合成得到含硫氮杂环卡宾配体的通式为[Fe~3(CO)~8(μ~3-S)~2L]的4个新羰合铁簇合物(1～4)。其配体S原子和杂环卡宾L皆来自配前体SL的劈开。对它们进行了元素分析,IR,^1HNMR和MS表征,并用X射线衍射测定了2的晶体分子结构,表明含硫氮杂环分子片CSC(SR)NNPh(L)的卡宾碳具有sp^2成键特征,其C~卡~宾键长为0.1960nm。2的分子几何构型维持母体物[Fe~3(CO)~9(μ~3-S)~2]的形状,其中卡宾基取代四方锥分子骨架Fe~3S~2基底平面Fe(1)S(1)Fe(3)S(2)的Fe(3)原子上径向位置的一个端羰基CO。     

Syntheses and crystal structures of SmIII and ThIV complexes with macrocyclic cavitand cucurbituril

Slow evaporation of solutions of samarium nitrate and thorium chloride in hydrochloric acid containing the macrocyclic cavitand cucurbituril (C₃₆H₃₆N₂₄O₁₂) afforded crystals of the [{Sm(H₂O)₅(NO₃)}₂(C₃₆H₃₆N₂₄O₁₂)](NO₃)₄·6.5H₂O and [{Th(H₂O)₅Cl}₂(C₃₆H₃₆N₂₄O₁₂)]Cl₆·13H₂O complexes, respectively. The [Sm(C₃₆H₃₆N₂₄O₁₂)(H₂O)₅(SO₄)][Sm(H₂O)₅(SO₄)₂]·17H₂O complex was generated upon heating (130 °C) of a mixture of samarium sulfate, cucurbituril, and water in a sealed tube. X-ray diffraction analysis demonstrated that the metal atoms in these complexes are bound to the portal oxygen atoms of the cucurbituril molecules. In addition, the portal oxygen atoms of cucurbituril are linked to the coordinated H₂O molecules via hydrogen bonds.     

Synthesis and crystal structure of EnH<Superscript>2</Superscript>[IrCl<Superscript>6</Superscript>]

The preparation of EnH²[IrCl⁶] is described. Crystal data for C₂H₁₀Cl₆IrN₂ are: a = 6.8972(11) Å, b = 6.9435(16) Å, c = 7.3354(11) Å; α = 88.269(3)°, β = 65.495(2)°, γ = 60.305(2)°, V = 270.76(9) ų, space group P1, Z = 1, d_calc = 2.864 g/cm³. Crystal chemical analysis of the general motif of the structure was performed by the translation sublattice identification technique. It has been found that complex anions [IrCl₆]^2? follow the nodes of a rather regular rhombohedral subcell with the parameters a_c = 7.1 Å, α_c = 64°.     

Synthesis and structural characterization of iron complexes with 2,2,2-tris(1-pyrazolyl)ethanol ligands: Application in the peroxidative oxidation of cyclohexane under mild conditions

The reactions of FeCl₂.2H₂O and 2,2,2-tris(1-pyrazolyl)ethanol HOCH₂C(pz)₃ (1) (pz = pyrazolyl) afford [Fe{HOCH₂C(pz)₃}₂][FeCl₄]Cl (2), [Fe{HOCH₂C(pz)₃}₂]₂[Fe₂OCl₆](Cl)₂·4H₂O (3·4H₂O), [Fe{HOCH₂C(pz)₃}₂][FeCl{HOCH₂C(pz)₃}(H₂O)₂]₂(Cl)₄ (4) or [Fe{HOCH₂C(pz)₃}₂]Cl₂ (5), depending on the experimental conditions. Compounds 1-5 were isolated as air-stable crystalline solids and fully characterized, including (1-4) by single-crystal X-ray diffraction analyses. The latter technique revealed strong intermolecular H-bonds involving the OH group of the scorpionate 2 and 3 giving rise to 1D chains which, in 3, are further expanded to a 2D network with intercalated infinite and almost plane chains of H-interacting water molecules. In 4, intermolecular π?π interactions involving the pyrazolyl rings are relevant.Complexes 2-5 display a high solubility in water (S_25 °Cca. 10-12 mg mL⁻¹), a favourable feature towards their application as catalysts (or catalyst precursors) for the peroxidative oxidation of cyclohexane to cyclohexanol and cyclohexanone, with aqueous H₂O₂/MeCN, at room temperature (TON values up to ca. 385).