The modification of bis(pyrazol-1-yl)methanes by chalcogen (S and Se) and their related reactions with organotin chloride and M(CO)5THF (M = Mo and W)

The modification of bis(pyrazol-1-yl)methane by sulfur or selenium on the methine carbon has been successfully carried out by the reaction of the bis(pyrazol-1-yl)methide anion, prepared in situ by the reaction of bis(pyrazol-1-yl)methane with n-BuLi, with elemental sulfur or selenium. These bis(pyrazol-1-yl)methylthiolate or selenolate anions reacted with Ph₂SnCl₂ to form new organotin derivatives CH(3,5-Me₂Pz)₂ESnPh₂Cl (Pz = pyrazol-1-yl, E = S (1) or Se (2)), which have been characterized by NMR, IR and elemental analysis. The molecular structure of 2 determined by X-ray structure analysis indicates that bis(3,5-dimethylpyrazol-1-yl)methylselenolate is a bidentate monoanionic κ²-[N,Se] chelating ligand. The treatment of CH(3,5-Me₂Pz)₂ESnPh₂Cl with W(CO)₅THF resulted in the decomposition of ligands to yield pyrazole derivative of (3,5-Me₂PzH)W(CO)₅, while direct treatment of bis(pyrazol-1-yl)methylthiolate or selenolate anions with M(CO)₅THF (M = Mo or W) formed their tricarbonyl metal anions . Succedent reaction of these carbonyl metal anions with Ph₂SnCl₂ or Ph₃SnCl yielded heterobimetalic compounds CH(Pz)₂EM(CO)₃SnPh_nCl_3−n (n = 2 or 3), which have also been characterized by ¹H NMR, IR and elemental analysis. The structure of CH(3,4,5-Me₃Pz)₂SW(CO)₃SnPh₃ (8) has been confirmed by X-ray single crystal diffraction, showing that bis(3,4,5-trimethylpyrazol-1-yl)methylthiolate acts as a tridentate, monoanionic κ³-[N,S,N] chelating ligand.     

Reactivity of bis(pyrazol-1-yl)methanes functionalized by 2-hydroxyphenyl and 2-methoxyphenyl on the methine carbon atom with W(CO)5THF

Reactions of 2-hydroxyphenyl and 2-methoxyphenylbis(pyrazol-1-yl)methanes as well as 2-hydroxyphenyl and 2-methoxyphenylbis(3,5-dimethylpyrazol-1-yl)methanes with W(CO)₅THF have been carried out. Heating 2-hydroxyphenylbis(pyrazol-1-yl)methane (L¹) with W(CO)₅THF in THF at reflux yielded complex (L¹)W(CO)₄.L¹, while similar reaction of 2-hydroxyphenylbis(3,5-dimethylpyrazol-1-yl)methane (L²) with W(CO)₅THF resulted in the cleavage of a C_sp3-N bond to generate 1,2-bis(2-hydroxyphenyl)-1,2-bis(3,5-dimethylpyrazol-1-yl)ethane (L) and pyrazole derivative W(CO)₅(3,5-Me₂PzH) (Pz = pyrazol-1-yl). These two fragments were connected together through strong O…H-N and O-H…N hydrogen bonds to form complex L.[W(CO)₅(3,5-Me₂PzH)]₂. The analogous results were observed in the treatment of 2-methoxyphenylbis(pyrazol-1-yl)methane (L³) with W(CO)₅THF, which gave product L′.[W(CO)₅(PzH)]₂ (L′ = 1,2-bis(2-methoxyphenyl)-1,2-bis(pyrazol-1-yl)ethane) as well as certain amount of complex (L³)W(CO)₄. In addition, during the reaction of 2-methoxyphenylbis(3,5-dimethylpyrazol-1-yl)methane (L⁴) with W(CO)₅THF, partial decomposition reactions took place to yield complexes (L⁴)W(CO)₄ and W(CO)₅(3,5-Me₂PzH), but no hydrogen bond was found between these two moieties.     

New multidentate heteroscorpionate ligands: N-Phenyl-2,2-bis(pyrazol-1-yl)thioacetamide and ethyl 2,2-bis(pyrazol-1-yl)dithioacetate as well as their derivatives

New multidentate heteroscorpionate ligands, N-phenyl-2,2-bis(3,5-dimethylpyrazol-1-yl)thioacetamide PhHNCSCH(3,5-Me₂Pz)₂ (1), N-phenyl-2,2-bis(3,4,5-trimethylpyrazol-1-yl)thioacetamide PhHNCSCH(3,4,5-Me₃Pz)₂ (2), and ethyl 2,2-bis(3,5-dimethylpyrazol-1-yl)dithioacetate EtSCSCH(3,5-Me₂Pz)₂ (8), have been synthesized and their coordination chemistry studied. These heteroscorpionate ligands can act as monodentate, bidentate, or tridentate ligands, depending on the coordinate properties of different metals. Reaction of W(CO)₆ with 1 or 2 under UV irradiation yields monosubstituted carbonyl tungsten complexes W(CO)₅L (L = 1 or 2), in which N-phenyl-2,2-bis(pyrazol-1-yl)thioacetamide acts as a monodentate ligand by the s-coordination to the tungsten atom. In addition, these monosubstituted tungsten complexes have also been obtained by heating ligand 1 or 2 with W(CO)₅THF in THF. While similar reaction of Fe(CO)₅ with 1, 2, or 8 under UV irradiation results in tricarbonyl iron complexes PhHNCSCH(3,5-Me₂Pz)₂Fe(CO)₃ (5), PhHNCSCH(3,4,5-Me₃Pz)₂Fe(CO)₃ (6), and EtSCSCH(3,5-Me₂Pz)₂Fe(CO)₃ (9), respectively, in which N-phenyl-2,2-bis(pyrazol-1-yl)thioacetamide or ethyl 2,2-bis(pyrazol-1-yl)dithioacetate acts as a bidentate ligand through one pyrazolyl nitrogen atom and the CS π-bond in an η²-C,S fashion side-on bonded to the iron atom to adopt a neutral bidentate κ²-(π,N) coordination mode. Treatment of the lithium salt of 1 with Co(ClO₄)₂ · 6H₂O gives complex [PhNCSCH(3,5-Me₂Pz)₂]₂Co(ClO₄) with the oxidation of cobalt(II) to cobalt(III), in which N-phenyl-2,2-bis(3,5-dimethylpyrazol-1-yl)thioacetamide acts as a tridentate monoanionic κ³-(N,N,S) chelating ligand by two pyrazolyl nitrogen atoms and the sulfur atom of the enolized thiolate anion.     

有机锡修饰的双吡唑甲烷及其与W(CO)5THF的反应

通过双吡唑甲基锂(LiCHPz₂)与有机锡卤化物(R₃SnX)的反应合成了一系列有机锡修饰的双吡唑甲烷配体(R₃SnCHPz₂).由于锡上取代基的不同,这些配体与W(CO)₅THF反应时表现出了不同的反应方式.三芳基锡修饰的双吡唑甲烷与W(CO)₅THF反应发生Sn-C(sp₃)键对W(0)中心的氧化加成;而三苄基锡修饰的双吡唑甲烷与其反应时仅给出羰基取代产物[Bz₃SnCHPz₂W(CO)₄].另外,二苯基苄基锡以及三(2-苯基-2-甲基丙基)锡修饰的双吡唑甲烷配体类似的反应导致配体的分解,产生单吡唑配体取代的羰基钨衍生物[W(CO)₅PzH]以及脱有机锡的双吡唑甲烷四羰基钨衍生物[CH₂Pz₂W(CO)₄].     

桥头碳上氮杂芳基功能化的双吡唑甲烷与羰基钨反应

研究了(氮甲基咪唑-2-基)双(3,5-二甲基吡唑)甲烷(L1),2-吡啶基双(3,5-二甲基吡唑)甲烷(L2)及4-吡啶基双(3,5-二甲基吡唑)甲烷(L3)与羰基钨的反应,合成了一系列以单齿,双齿及三齿氮配位的羰基金属衍生物LW(CO)5(L=L1或L3),LW(CO)4(L=L1,L2或L3)和LW(CO)3(L=L1或L2)。核磁,红外及X-射线单晶衍射分析表明这3种配体表现出了可变的配位方式。在LW(CO)5中,当配体为L1时,其倾向于通过咪唑氮与金属配位,而为L3则倾向于利用吡啶氮与金属作用;在LW(CO)4中,配体L1表现为通过咪唑氮和吡唑氮原子配位的[N,N′]双齿配体,而L2和L3表现为通过吡唑氮原子配位的[N,N]双齿配体;在LW(CO)3中,L1和L2起着[N,N,N′]三齿螯合配体的作用。     

桥头碳上氮杂芳基功能化的双吡唑甲烷与羰基钨反应

研究了(氮甲基咪唑-2-基)双(3,5-二甲基吡唑)甲烷(L¹),2-吡啶基双(3,5-二甲基吡唑)甲烷(L²)及4-吡啶基双(3,5-二甲基吡唑)甲烷(L³)与羰基钨的反应,合成了一系列以单齿,双齿及三齿氮配位的羰基金属衍生物LW(CO)₅ (L=L¹或L³),LW(CO)₄ (L=L¹,L²或L³)和LW(CO)₃ (L=L¹或L²).核磁,红外及X-射线单晶衍射分析表明这3种配体表现出了可变的配位方式.在LW(CO)₅中,当配体为L¹时,其倾向于通过咪唑氮与金属配位,而为L³则倾向于利用吡啶氮与金属作用;在LW(CO)₄中,配体L¹表现为通过咪唑氮和吡唑氮原子配位的[N,N']双齿配体,而L²和L³表现为通过吡唑氮原子配位的[N,N]双齿配体;在LW(CO)₃中,L¹和L²起着[N,N,N']三齿螯合配体的作用.     

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.     

Chemical behavior of ortho-hydroquinone-based bis(pyrazol-1-yl)methane ligands in the presence of palladium(II) chloride

The synthesis, structural characterization, and coordination behavior of ditopic ortho-hydroquinone-based bis(pyrazol-1-yl)methane ligands (ortho-(OH)₂C₆H₃-4-CHpz₂, ortho-(OH)₂C₆H₃-4-CH(3-Phpz)₂, and ortho-(OH)₂C₆H₃-4-CH(3-tBupz)₂) with pyrazole, 3-phenylpyrazole, and 3-tert-butylpyrazole as donors are described. The reaction of a soluble PdCl₂-source with ortho-(OH)₂C₆H₃-4-CHpz₂ in acetonitrile yielded the related square-planar N,N-coordinated Pd(II) dichloride complex, whereas treatment of ortho-(OH)₂C₆H₃-4-CH(3-Phpz)₂ or ortho-(OH)₂C₆H₃-4-CH(3-tBupz)₂ with PdCl₂ in acetonitrile resulted in degradation of these ligands. The Pd(II) complexes trans-(3-PhpzH)₂PdCl₂ and trans-(3-tBupzH)₂PdCl₂ were isolated and fully characterized including X-ray diffraction analyses.     

Synthesis, structure and characterization of M---Sn (M=Mo, W) bonded heterobimetallic complexes containing bis(pyrazol-1-yl)methane ligands

The reaction of bis(pyrazol-1-yl)methane tetracarbonylmolybdenum(0) or tungsten(0) complexes with RSnCl₃ (R=Ph, Cl) at room temperature yielded heterobimetallic complexes CH₂(Pz)₂M(CO)₃(Cl)(SnCl₂R) (Pz represents substituted pyrazole; M=Mo or W; R=Ph or Cl) in good yields, which have been characterized by elemental analysis, ¹H NMR and IR spectroscopy. The reaction of bis(3,5-dimethyl-4-halopyrazol-1-yl)methane tetracarbonyl tungsten with PhSnCl₃ did not take place even in refluxing CH₂Cl₂. The electronic and steric characteristics of substituents on the pyrazole ring remarkably influence the structures of the products. The structures of CH₂(3,5-Me₂-4-BrPz)₂W(CO)₃(Cl)(SnCl₃) (8) and CH₂(4-BrPz)₂Mo(CO)₃(μ-Cl)(SnCl₂Ph) (17) (Pz: pyrazole) determined by X-ray crystallography show that no chlorine-bridged W---Sn bond is observed in complex 8, while one chlorine-bridged Mo---Sn bond exists in complex 17. The Sn---M bond length is 2.7438(5) Å in complex 8 (W---Sn) and 2.7559(4) Å in complex 17 (Mo---Sn).     

Copper(II) complexes of bis(pyrazol-1-yl)methane - Synthesis, spectroscopic characterization, X-ray structure and DFT calculations

Two novel copper(II) complexes incorporating bis(pyrazol-1-yl)methane ligand (bpzm) have been synthesized. The compounds [CuCl(bpzm)₂(H₂O)]Cl·H₂O (1) and [Cu(N₃)₂(bpzm)]_n (2) have been studied by IR, UV-Vis spectroscopy and X-ray crystallography. The experimental studies on the compounds 1 and 2 have been accompanied computationally by the density functional theory (DFT) calculations.     

Syntheses,crystal structures and properties of two cadmium coordination polymers containing bis (2-methylimidazol-1-yl)methane(2-mBIM) and bis (imidazol-1-yl)methane (BIM) ligands

Coordination polymers, {[Cd(2-mBIM)₃](ClO₄)₂} _n (1) and [Cd(BIM)₂(NO₃)₂] _n (2), have been prepared from the reaction of bis(2-methylimidazol-1-yl)methane(2-mBIM) with Cd(ClO₄)₂ and bis(imidazol-1-yl)methane (BIM) with Cd(NO₃)₂ in ethanol and water, respectively. Their structures were characterized by single crystal X-ray diffraction and IR spectroscopy. Compound 1 crystallizes in the rhombohedral space group R-3c with a = b = 12.3617(5) Å, c = 38.896(3) Å, γ = 120°, V = 5147.5(5) ų, z = 6. The Cd^II occupies a crystallographic inversion center and is coordinated by six N atoms from six distinct 2-mBIM ligands to form a slightly distorted octahedral geometry. Each 2-mBIM is coordinated to two Cd^II cations, linking alternatively four Cd^II cations, resulting in a 32-membered M₄L₄ macrometallacycle. Compound 2 crystallizes in the monoclinic space group C2/m with a = 14.400(3) Å, b = 9.3894(18) Å, c = 8.6926(17) Å, β = 123.499(2)°, V = 980.1(3) ų, z = 2. The Cd coordinates to four nitrogen atoms from four different BIM and two nitrates to form a slightly distorted octahedral geometry. The BIM ligands bridge to form a 1-D infinite double-bridged chain structure with 16-membered M₂L₂ macrometallacyclic structural units.     

Bis(pyrazol-1-yl)propane as a bulky Ligand: X-ray Crystal Structure Determination of its Adduct with Zinc(II) Chloride

The steric misfit between a geminal bis(pyrazol-1-yl)propane ligand and tetrahedral coordination leads to distortion of the latter in the title compound: N? Zn? N is 89.5(1)°, Cl? Zn? Cl 116.78(5)°. Comparison of the Zn? N (2.058(3), 2.046(3) Å) and Zn? Cl (2.209(1), 2.229(1) Å) distances with those of related compounds evidences the steric bulkiness of the title ligand.     

A novel rhenium(III) complex with bis(pyrazol-1-yl)methane: X-ray structure and DFT calculations for [ReCl3(bpzm)(PPh3)]

The [ReCl₃(MeCN)(PPh₃)₂] complex reacts with bis(pyrazol-1-yl)methane (bpzm) to give [ReCl₃(bpzm)(PPh₃)]. This compound has been studied by IR, UV–Vis spectroscopy, magnetic measurement and X-ray crystallography. The molecular orbital diagram of [ReCl₃(bpzm)(PPh₃)] has been calculated with the density functional theory (DFT) method. The spin-allowed triplet–triplet electronic transitions of [ReCl₃(bpzm)(PPh₃)] have been calculated with the time-dependent DFT method, and the UV–Vis spectrum of the title compound has been discussed on this basis. The magnetic behavior is characteristic of a mononuclear d⁴ low-spin octahedral Re(III) complex (³T_1g ground state) and arises because of the large spin–orbit coupling (ζ = 2500 cm⁻¹), which gives a diamagnetic ground state.     

Rhodium(I) carbonyl complexes of mono selenium functionalized bis(diphenylphosphino)methane and bis(diphenylphosphino)amine chelating ligands and their catalytic carbonylation activity

The chelate complexes of the types (1) and (2) have been synthesized and characterized by IR and NMR spectroscopy. The lower shift of the ν(P-Se) bands and downfield shift of the ³¹P-{¹H}NMR signals for both P(III) and P(V) atoms in 1 and 2 compared to the corresponding free ligands indicate chelate formation through selenium donor. 1 and 2 show terminal ν(CO) bands at 1977 and 1981 cm⁻¹, respectively, suggesting high electron density at the metal center. The molecular structure of 2 has been determined by single-crystal X-ray diffraction. The rhodium atom is at the center of a square planar geometry having the phosphorus and selenium atoms of the chelating ligand at cis-position, one carbonyl group trans- to selenium and one chlorine atom trans- to phosphorus atom. 1 and 2 undergo oxidative addition (OA) reaction with CH₃I to produce acyl complexes (3) and (4), respectively. The kinetics of the OA reactions reveal that 1 undergoes faster reaction by about 4.5 times than 2. The catalytic activity of 1 and 2 in carbonylation of methanol was higher than that of the well known species [Rh(CO)₂I₂]⁻ and 2 shows higher catalytic activity compared to 1.     

Dinuclear Pentacarbonyl Tungsten Complex Bridged by Bis（3,5-dimethylpyrazol- 1- yl ） methane

IntroductionPoly(pyrazol 1 yl)alkanes,especiallybis(pyrazol 1 yl)alkanes ,havebeenoneofpopularpolydentatenitrogendonorligandssinceTrofimenko’sfirstreport1andJulia’slatermodification .2 Ithasbeenfoundthatthecoordinationbehavioroftheseligandscaneasilybeadjustedbychang ingtheelectronicandstericcharacteristicsofsubstituentsonthepyrazolering .Recentinvestigationshavealsoshownthatthecentralcarbonatomoftheseligandscanbemodifiedbythevariousfunctionalgroupstoformversatileheteroscorpionateligands ,wh…     

Oxygenation of aromatic substrates over Pd(II) catalysts bearing bis(pyrazol-1-yl)alkanes ligands

Summary Liquid phase oxygenation of 1-tetralin, ethylbenzene, cyclohexane and toluene is describe using four catalyst precursors such as: (CH₂)n(PzR)PdCl₂ (n=1,2; R=H, Me) at T=100°C, P_air= 5.4 atm, substrate/catalyst ratio=100 for 3 h,. It was observed that the type of alkyl bridge between the pyrazolyl ligands has an effect on the catalytic activity.     

Synthesis and structural characterization of ferrocene-based bis(pyrazol-1-yl)borate ligands: FcB(Me)pz2K, Fc2Bpz2K, and 1,1′-fc[B(Me)pz2]2K2 (Fc: ferrocenyl, fc: ferrocenylene, pz: pyrazolyl)

Reaction of the ferrocenyl(dimethylamino)boranes FcB(Me)NMe₂, Fc₂BNMe₂, and 1,1′-fc[B(Me)NMe₂]₂ with 1:1 mixtures of pyrazole and potassium pyrazolide in refluxing THF gave the potassium salts of the ferrocene-based bis(pyrazol-1-yl)borate ligands FcB(Me)pz₂K, Fc₂Bpz₂K, and 1,1′-fc[B(Me)pz₂]₂K₂ in good yield (Fc: ferrocenyl, fc: ferrocenylene, pz: pyrazolyl). In the solid state, FcB(Me)pz₂K and Fc₂Bpz₂K form centrosymmetric dimers with short K?Cp contacts suggesting an η⁵ coordination mode of the potassium ion. The crystal lattice of the ditopic ligand 1,1′-fc[B(Me)pz₂]₂K₂ consists of coordination polymer strands featuring essentially the same structural motif that has been observed for the monotopic derivatives. All three scorpionate ligands are thus promising building blocks for the preparation of ferrocene-containing multiple-decker sandwich complexes.     

Synthesis and spectroscopic characterization of new organotin(IV) complexes with bis(3,5-dimethylpyrazol-1-yl)dithioacetate

New organotin(IV) derivatives containing the anionic ligand bis(3,5-dimethylpyrazolyl)dithioacetate [L₂CS₂]^? have been synthesized by reaction of SnR _n X_{4? n} (R?=?Me, Ph, ⁿ Bu or Cy; n?=?1–3) acceptors and Li[L₂CS₂]. Mononuclear complexes of the type [L₂CS₂]R _n SnCl_{4? n ?1}} have been obtained and fully characterized by elemental analyses and FT-IR in the solid state, and by NMR (¹H and ¹¹⁹Sn) spectroscopy, conductivity measurements and electrospray ionization mass spectrometry (ESI-MS) in solution. ESI-MS spectra of methanol solutions of diorganotin derivatives, recorded with fragmentor potentials of 0, 50, 100 and 150?V, show the occurrence at 150?V of peaks attributable to the loss of the CS₂ group from the ligands and the formation of stable tetraorganodistannoxane species.     

Synthesis, spectroscopic characterization, X-ray structure and DFT calculations of rhenium(III) complex with bis(3,5-dimethylpyrazol-1-yl)methane

[ReCl₃(MeCN)(PPh₃)₂] reacts with bis(3,5-dimethypyrazol-1-yl)methane (bdmpzm) in acetone to give [ReCl₃(bdmpzm)(PPh₃)]. The compound has been studied by IR, UV–Vis spectroscopy and X-ray crystallography. The molecular orbital diagram of [ReCl₃(bdmpzm)(PPh₃)] has been calculated with the density functional theory (DFT) method.     

Approaches to the Synthesis of Dicarboxylic Derivatives of Bis(pyrazol-1-yl)alkanes

Carboxylation of bis(pyrazol-1-yl)alkanes by oxalyl chloride was studied. It was found that 4,4′-dicarboxylic derivatives of substrates with electron-donating methyl groups and short linkers (from one to three methylene groups) can be prepared using this method. Longer linkers lead to significantly lower product yields, which is probably due to instability of the intermediate acid chlorides that are initially formed in the reaction with oxalyl chloride. Thus, bis(pyrazol-1-yl)methane gave only monocarboxylic derivative even with a large excess of oxalyl chloride and prolonged reaction duration. An alternative approach involves the reaction of ethyl 4-pyrazolecarboxylates with dibromoalkanes in a superbasic medium (potassium hydroxide–dimethyl sulfoxide) and is suitable for the preparation of bis(4-carboxypyrazol-1-yl)alkanes with both short and long linkers independent of substitution in positions 3 and 5 of pyrazole rings. The obtained dicarboxylic acids are interesting as potential building blocks for metal-organic frameworks.