Propane Ligands Research Articles

DFT study on mechanism of nickel-catalyzed decarbonylative reductive alkylation of aroyl fluorides with alkyl bromides

The mechanism of the nickel-catalyzed decarbonylative reductive alkylation of aroyl fluorides with alkyl bromides is investigated using density functional theory calculations. The calculation result shows that the reaction mechanism involves sequential steps of C–F bond oxidative addition, decarbonylation, alkyl radical addition, C(sp2)–C(sp3) reductive elimination to afford the product, single electron transfer (SET) and reduction by Zn to regenerate the initiating complex. And the step of C–F bond oxidative addition was found to be the rate-determining step. The decarbonylation should occur before the alkyl radical addition. The effects of 1,3-bis(diphenylphosphino)propane (DPPP) ligand and different substrates on the reactivity were also analyzed. These calculation results disclosed the detailed reaction mechanism and shed lights on some ambiguous suggestions from experiments.

A Continuous-Wave EPR Investigation into the Photochemical Transformations of the Chromium(I) Carbonyl Complex [Cr(CO)4bis(diphenylphosphino)]+ and Reactivity with 1-hexene.

Chromium complexes containing a bis(diphenylphosphino) ligand have attracted significant interest over many years due to their potential as active catalysts for ethylene oligomerisation when combined with suitable co-catalysts such as triethylaluminium (TEA) or methylaluminoxane (MAO). While there has been considerable attention devoted to the possible reaction intermediates and the nature of the Cr oxidation states involved, the potential UV photoactivity of the Cr(I) complexes has so far been overlooked. Therefore, to explore the photoinduced transformations of bis(diphenylphosphino) stabilized Cr(I) complexes, we used continuous-wave (CW) EPR to study the effects of UV radiation on a cationic [Cr(CO)4(dppp)]+[Al(OC(CF3)3)4]- complex (1), where dppp represents the 1,3 bis-(diphenylphosphino)propane ligand, Ph2P(C3H6)PPh2. Our preliminary investigations into the photochemistry of this complex revealed that [Cr(CO)4(dppp)]+ (1) can be readily photo-converted into an intermediate mer-[Cr(CO)3(κ1-dppp)(κ2-dppp)]+ complex (2) and eventually into a trans-[Cr(CO)2(dppp)2]+ complex (3) in solution at room temperature under UV-A light. Here, we show that the intermediate species (2) involved in this transformation can be identified by EPR at much lower temperature (140 K) and at a specific wavelength (highlighting the wavelength dependency of the reaction). In addition, small amounts of a 'piano-stool'-type complex, namely [Cr(CO)2(dppp-η6-arene)]+ (4), can also be formed during the photoconversion of [Cr(CO)4(dppp)]+ using UV-A light. There was no evidence for the formation of the [Cr(L-bis-η6-arene)]+ complex (5) in these UV irradiation experiments. For the first time, we also evidence the formation of a 1-hexene coordinated [Cr(CO)3(dppp)(1-hexene)]+ complex (6) following UV irradiation of [Cr(CO)4(dppp)]+ in the presence of 1-hexene; this result demonstrates the unprecedented opportunity for exploiting light activation during Cr-driven olefin oligomerisation catalysis, instead of expensive, difficult-to-handle, and hazardous chemical activators.

Poly[[[μ3-3-(2-carboxyl-atophen-yl)propionato][μ2-N,N'-(ethane-1,2-di-yl)bis-(pyridine-4-carbox-amide)]copper(II)] monohydrate], a layered coordination polymer with (4,4) topology.

In the title compound, {[Cu(C10H8O4)(C14H14N4O2)]·H2O}n, the CuII cations are coordinated in a square-pyramidal fashion, with trans pyridyl-N donor atoms from two N-(2-(pyridin-3-yl-amino)-eth-yl)isonicotinamide (pein) ligands in the basal plane. The other three coordination sites are taken up by carboxyl-ate O-atom donors from three different 3-(2-carb-oxy-phen-yl)propionate (cpp) ligands. The central ethyl-enedi-amine segments of the pein ligands are disordered equally over two sets of positions. {Cu2O2} rhomboid clusters are connected into [Cu(cpp)(pein)]n (4,4) coordination polymer grids by the full span of the cpp and pein ligands. Individual layer motifs stack in an AAA pattern along the a axis by means of inter-layer hydrogen-bonding inter-actions.

A Cd(II) MOF based on 5-ethoxyisophthalate and 1,3-bis(4-pyridyl)propane ligands with a twofold interpenetrated crystal structure showing room temperature phosphorescence

Abstract A metal-organic framework (MOF) {[Cd(EtOIPA)(bpp)(H2O)]·2H2O} n (1) has been synthesized under basic hydrothermal conditions by using of 5-ethoxyisophthalic acid (EtOIPAH2) and 1,3-bis(4-pyridyl)propane (bpp) as reagents for cadmium nitrate. Compound 1 was characterized by elemental analysis, single-crystal X-ray diffraction and UV/Vis spectroscopy. In 1, the bpp ligands extend the EtOIPA-Cd chains along the ab plane to form a 2-fold 3D interpenetrating network. Compound 1 emits blue phosphorescence at room temperature with a long lifetime of 4.2 ms.

Elucidating the exchange interactions in a {GdIIICuII4} propellor.

The multinucleating ligand 2,2'-(propane-1,3-diyldiimino)bis[2-(hydroxymethyl)-propane-1,3-diol] (bis-tris propane, H6L) is used in the design of a new family of 3d-4f complexes that display an unusual {LnCu4} four-blade propeller topology. We report the synthesis, structure and magnetic characterisation of [LnCu4(H4L)4](Cl)2(ClO4)·6CH3OH, where Ln = Gd (1), Tb (2), Dy (3), La (4). Previously we have used CH3COO- and NO3- as co-ligands with bis-tris propane, but here the use of Cl- and ClO4- leads to coordination of four {Cu(H4L)} units around the central Ln ion. A magneto-structural analysis reveals that the geometrical arrangement of the Cu(II) centres defined by the H4L2- ligands controls the magnetic communication between the different metal centres. DFT calculations performed on the isotropic (Gd) and diamagnetic (La) systems 1 and 4 help to unravel the intriguing exchange interactions.

Cationic Palladium Catalyzed Nonalternating Copolymerization of Ethylene with Carbon Monoxide: Microstructure Analysis and Computational Study†

Comprehensive SummaryThe introduction of carbonyl group with a high density in polyethylene backbone corresponds to polyketone materials, which features excellent mechanical strength, crystallinity, photodegradability, hydrophilicity, surface and barrier properties. Due to the extremely high binding affinity of carbon monoxide (CO) and kinetic preference for its subsequent insertion, the formation of nonalternating structure with extra ethylene insertion is exceptionally challenging, however, this nonalternating strategy is of significant importance for polymer modification in term of processing and solubility. Here, we have communicated our study on cationic palladium coordinated diphosphazane monoxide (PNPO) for the nonalternating copolymerization of ethylene with CO, the systematical investigation on the amine and phosphine oxide moieties in PNPO platform in term of electronic and steric modulation has been performed. It is discovered that the installation of aliphatic structure on amine moiety favors the improvement of catalyst activity and longevity, while the amino groups on phosphine oxide moiety promotes the nonalternating copolymerization. In particular, we have computationally investigated herein the aspects of the nonalternating degree by comparing with PNPO platform and 1,3‐bis(diphenylphosphanyl)propane ligands based palladium catalysts. These mechanistic studies can help to understand the catalyst structure and polyketone property relationships and shed light on future design of high‐performance copolymerization catalysts.

Carboxylate-Capped Analogues of Ru265 Are MCU Inhibitor Prodrugs.

The mitochondrial calcium uniporter (MCU) is a transmembrane protein that resides on the inner membrane of the mitochondria and mediates calcium uptake into this organelle. Given the critical role of mitochondrial calcium trafficking in cellular function, inhibitors of this channel have arisen as tools for studying the biological relevance of this process and as potential therapeutic agents. In this study, four new analogues of the previously reported Ru-based MCU inhibitor [ClRu(NH3)4(μ-N)Ru(NH3)4Cl]Cl3 (Ru265) are reported. These compounds, which bear axial carboxylate ligands, are of the general formula [(RCO2)Ru(NH3)4(μ-N)Ru(NH3)4(O2CR)]X3, where X = NO3- or CF3SO3- and R = H (1), CH3 (2), CH2CH3 (3), and (CH2)2CH3 (4). These complexes were fully characterized by IR spectroscopy, NMR spectroscopy, and elemental analysis. X-ray crystal structures of 1 and 3 were obtained, revealing the expected presence of both the linear Ru(μ-N)Ru core and axial formate and propionate ligands. The axial carboxylate ligands of complexes 1-4 are displaced by water in buffered aqueous solution to give the aquated compound Ru265'. The kinetics of these processes were measured by 1H NMR spectroscopy, revealing half-lives that span 5.9-9.9 h at 37 °C. Complex 1 with axial formate ligands underwent aquation approximately twice as fast as the other compounds. In vitro cytotoxicity and mitochondrial membrane potential measurements carried out in HeLa and HEK293T cells demonstrated that none of these four complexes negatively affects cell viability or mitochondrial function. The abilities of 1-4 to inhibit mitochondrial calcium uptake in permeabilized HEK293T cells were assessed and compared to that of Ru265. Fresh solutions of 1-4 are approximately 2-fold less potent than Ru265 with IC50 values in the range of 14.7-19.1 nM. Preincubating 1-4 in aqueous buffers for longer time periods to allow for the aquation reactions to proceed increases their potency of mitochondrial uptake inhibition to match that of Ru265. This result indicates that 1-4 are aquation-activated prodrugs of Ru265'. Finally, 1-4 were shown to inhibit mitochondrial calcium uptake in intact, nonpermeabilized cells, revealing their value as tools and potential therapeutic agents for mitochondrial calcium-related disorders.

A new Pd(II) complex containing acetophenone oxime and 1,3-Bis(diphenylphosphino)propane ligands; crystal structure, catalytic activity, molecular docking and in vitro cytotoxic evaluation

A new palladium (II) complex of the type [Pd{C,N-C6H4{C(Me) = NOH}-2}(dppp)]ClO4 (2) has been prepared by the reaction of the cyclopalladated oxime complex [Pd{C,N-C6H4{C(Me) = NOH}-2}(μ-Cl)]2 (1) with 1,3-Bis(diphenylphosphino)propane (dppp). The new complex has been synthesized via a bridge-splitting reaction in the presence of NaClO4 under mild conditions. Complex 2 was fully characterized by elemental analysis (CHN), spectroscopic methods (IR, 1H-, 31P-, 13C NMR) and single-crystal X-ray diffraction analysis. The structure shows the palladium atom to be in a slightly distorted square-planar geometry surrounded by one C,N-chelating oxime ligand and one P,P-chelating dppp ligand forming five- and a six-membered metallocyclic rings, respectively. The catalytic activity of complex 2 has been evaluated using Suzuki cross coupling reactions. The coupled products of these reactions were obtained in good to excellent yields and purity, low catalyst loading and short reaction times. The cytotoxic activity of complexes 1 and 2 were comparatively studied against HeLa, A549, and 1321 N1 cell lines, which showed a greater efficiency of the mononuclear complex 2 over the binuclear complex 1. Finally, molecular docking simulation was employed as a computational method to investigate the interactions of complexes 1 and 2 with the protein involved in apoptosis.

Design of molecular magnetic materials based on a new family of mixed-lanthanide Co-Ln clusters by the use of the 1,3-Bis[tris(hydroxymethyl)-methylamino]propane ligand

A new family of tetranuclear Co-Ln clusters, including both single and mixed-lanthanides, was synthesized by the use of a bis-tris propane ligand. Our studies showed that although single-lanthanide {Co3Ln} compounds assembled from lanthanide elements heavier than Nd are not accessible, mixed-lanthanide analogues retaining the original structure can be obtained. An array of magnetic measurements was used to reveal the single-molecule magnet behaviors and magnetocaloric effect of Co-Ce/Dy and Co-Ce/Gd clusters, respectively. Thus, this study may open up new avenues for the design of molecular magnetic materials by synthesizing mixed-lanthanide 3d-4f clusters.

Electrochemical sensing of hydrogen peroxide on a carbon paste electrode modified by a silver complex based on the 1,3-bis(1H-benzimidazole-2-yl)propane ligand

Abstract A new carbon paste electrode (Ag-CPE) modified with a nitrogen heterocyclic silver(I) complex, [Ag2(BBP)2](pic)2·CH3OH (BBP = 1,3-bis(1H-benzimidazol-2-yl)propane, pic = picrate), was developed as a highly sensitive and simple electrochemical sensor for the determination of hydrogen peroxide. The Ag(I) complex was prepared by an interface reaction and characterized by elemental analysis, IR and UV/Vis spectra and single crystal X-ray diffraction. The Ag(I) complex shows a dinuclear cluster structure, which is formed by two BBP ligands bridging two Ag (I) centers and an Ag–Ag interaction (d Ag–Ag = 3.0875 Å). Cyclic voltammetry and chronoamperometry studies showed that the electrochemical sensing performance of Ag-CPE for H2O2 was improved in 0.2 m phosphate buffer solution (PBS, pH = 6). The electrochemical H2O2 sensor Ag-CPE exhibits a wide linear detection range from 0.5 to 4.0 mm and a lower detection limit of 0.39 μm with a relatively high sensitivity of 6.77 μA mm −1. Moreover, the sensor also shows good anti-interference properties and stability. The results prove that the Ag(I) complex based on the bis(benzimidazole) ligand may be an efficient component of electrode materials.

Two 3D supramolecular isomeric Zn(II)-MOFs as photocatalysts for photodegradation of methyl violet dye

Two new Zn(II) metal-organic-frameworks displaying supramolecular isomerism have been synthesized using 1,3-bis(2-methylimidazolyl)propane (bmp) and 1,3,5-benzenetricarboxylic acid (H3BTC). The isomer [NH2(CH3)2][Zn2O(bmp)(BTC)] (1) adopt 2-fold interpenetrating framework topology defined by bey-type of interpenetration while another isomer [NH2(CH3)2][Zn2O(bmp)(BTC)].1.5DMF (2) adopt 2-fold interpenetrating framework topology defined by CdSO4-type of interpenetration. The difference in topologies of two MOFs can be ascribed to the flexibility of 1,3-bis(2-methylimidazolyl)propane ligand; because of which 2 lies on a crystallographic mirror plane. Both MOFs display efficient photocatalytic properties for the photodegradation of model aromatic dye methyl violet (MV). The photocatalytic mechanism in both the MOFs have been explained by using density of states calculations. Moreover, chromatography-mass spectrometry (LC-MS) has been performed to further validate the potential photodegradation mechanism of MV.

Pillared-layer zinc-organic framework based on 4,4′-oxybis(benzoic acid) and 1,3-bis(4-pyridyl)propane as a chemical sensor for the detection of nitroaromatics

Metal–organic frameworks are a class of highly crystalline hybrid materials that have received considerable attention due to their potential applications in different areas. The molecular recognition and sensing of small molecules pollutants by MOFs has gained the attention of researchers around the world. Herein, a new pillared-layer zinc-organic framework (CFU-1) is introduced which has been synthesized via a combination of 4,4´-oxybis(benzoic acid) (H2OBA) and 1,3-bis(4-pyridyl)propane (BPP) ligands. The structure of this framework has been determined by X-ray crystallography, FT-IR spectroscopy and elemental analysis. The structural features of this MOF as well as its stability and porosity were studied. The potential of the framework was examined for sensing nitro-analytes such as nitrobenzene (NB), 1,3-dinitrobenzene (DNB) and 2,4,6-trinitrotoluene (TNT). The framework stability during the chemo-sensing experiment was studied using the powder X-ray diffraction (XRD) and Field-emission scanning electron microscopy (FE-SEM). Our study reveals the potential of CFU-1 in the molecular recognition of nitroaromatics.

Cadmium coordination compounds with flexible ligand 1,3-bis(1,2,4-triazol-1-yl)propane: Synthesis, structure and luminescent properties

Six new cadmium coordination compounds with flexible 1,3-bis(1,2,4-triazol-1-yl)propane (btrp) ligand, [Cd(btrp)(H2O)2(NO3)2]n (1), [Cd(btrp)2(NO3)2]·H2O (2), [Cd(btrp)Hal2] (3–5) (Hal = Cl, Br, I) and [Cd2(btrp)2(DMF)2(μ2-Br)2Br2] (6) were synthesized. The crystal structures of the complexes 1 and 6 were determined. 1 has 1D polymeric structure while 6 is binuclear. The latter reveals rare gauche–gauche conformation of btrp ligand. Luminescent properties of 1–6 in the solid state were studied in comparison with free btrp. The emission of the compounds corresponds to intraligand transitions, while the bands exhibit complicated shape that can be described by two Gauss functions.

Gem-Dialkyl Effect in Diphosphine Ligands: Synthesis, Coordination Behavior, and Application in Pd-Catalyzed Hydroformylation

A series of palladium complexes with C3-bridged bidentate bis(diphenylphosphino)propane ligands with substituents of varying steric bulk at the central carbon have been synthesized. The size of the...

Catena-Poly[[diaquacadmium(II)]-μ2-3-(4-carboxylatophenyl)propionato

In the title compound, [Cd(C10H8O4)(H2O)2)] n , the CdII cation is coordinated in a distorted trigonal–prismatic fashion. 3-(4-Carboxyphenyl)propionate (cpp) ligands connect the CdII cations into zigzag [Cd(cpp)(H2O)2)] n coordination polymer chains, which are oriented parallel to [101]. The chains aggregate into supramolecular layers oriented parallel to (10\overline{1}) by means of O—H...O hydrogen bonding between bound water molecules and ligating cpp carboxylate O atoms. The layers stack in an ABAB pattern along [100] via other O—H...O hydrogen-bonding mechanisms also involving the bound water molecules. The crystal studied was an inversion twin.

A propionate-functionalized polyoxovanadate K2[V10O16(OH)6(CH3CH2CO2)6]·20H2O: As catalyst for degradation of methylene blue

By self-assembly of the KVO3 raw material with propionate ligand using hydrazine hydrate as reducing agents in conventional aqueous solution, a novel propionate-functionalized polyoxovanadate K2[V10O16(OH)6(CH3CH2CO2)6]·20H2O (1) has been successfully synthesized and further structurally characterized by IR spectrum, powder X-ray diffraction (PXRD), thermogravimetric (TG), and single-crystal X-ray diffraction analysis. Structural analysis demonstrates that the polyanion [V10O16(OH)6(CH3CH2CO2)6]2− of 1 is composed of the {V10}-based polyoxovanadate which is further anchored by 6 propionate ligands to form a propionate-stabilized decavanadate. The {V10} building unit of 1 is completely different from the classical [V10O28]6− ion. The catalytic property of 1 for the degradation of methylene blue (MB) was investigated, and the result indicates that 1 exhibits excellent catalytic activity for the degradation of MB.

One-dimensional copper(II) coordination polymers based on 1,3-bis(pyridin-4-yl)propane and diimine ligands.

Two one-dimensional (1D) coordination polymers (CPs), namely catena-poly[[[aqua(2,2'-bipyridine-κ2N,N')(nitrato-κO)copper(II)]-μ-1,3-bis(pyridin-4-yl)propane-κ2N:N'] nitrate], {[Cu(NO3)(C10H8N2)(C13H14N2)(H2O)]·NO3}n (1), and catena-poly[[[aqua(nitrato-κO)(1,10-phenanthroline-κ2N,N')copper(II)]-μ-1,3-bis(pyridin-4-yl)propane-κ2N:N'] nitrate], {[Cu(NO3)(C12H8N2)(C13H14N2)(H2O)]·NO3}n (2), have been synthesized using [Cu(NO3)(NN)(H2O)2]NO3, where NN = 2,2'-bipyridine (bpy) or 1,10-phenanthroline (phen), as a linker in a 1:1 molar ratio. The CPs were characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis and single-crystal X-ray structure determination. The 1,3-bis(pyridin-4-yl)propane (dpp) ligand acts as a bridging ligand, leading to the formation of a 1D polymer. The octahedral coordination sphere around copper consists of two N atoms from bpy for 1 or phen for 2, two N atoms from dpp, one O atom from water and one O atom from a coordinated nitrate anion. Each structure contains two crystallographically independent chains in the asymmetric unit and the chains are linked via hydrogen bonds into a three-dimensional network.

Hydrating the Bispropionate Notch in Malaria Pigment: A New Structural Motif in the Iron(III)(deuteroporphyrin) Dimer.

Treating deuterohemin, chloro(deuteroporphyrinato)iron(III), with a non-coordinating base in DMSO/methanol allows for the isolation of [(deuteroporphyrinato)iron(III)]2 , deuterohematin anhydride (DHA), an analogue of malaria pigment, the natural product of heme detoxification by malaria. The structure of DHA obtained from this solvent system has been solved by X-ray powder diffraction analysis and displays many similarities, yet important structural differences, to malaria pigment. Most notably, a water molecule of solvation occupies a notch created by the propionate side chains and stabilizes a markedly bent propionate ligand coordinated with a long Fe-O bond, and a carboxylate cluster associated with water molecules is generated. Together, these features account for its increased solubility and more open structure, with an increased porphyrin-porphyrin separation. The IR spectroscopic signature associated with this structure also accounts for the strong IR band at 1587 cm-1 seen for many amorphous preparations of synthetic malaria pigment, and it is proposed that stabilizing these structures may be a new objective for antimalarial drugs. The important role of the vinyl substituents in this biochemistry is further demonstrated by the structure of deuterohemin obtained by single-crystal X-ray diffraction analysis.

Crystal Engineering and Magnetostructural Properties of Newly Designed Azide/Acetate-Bridged Mn12 Coordination Polymers

Crystal engineering of the coordination polymers where polynuclear clusters are building blocks constitutes an emerging class of chemistry. The fine-tuning of the structural motifs leads to interesting and varying magnetic properties. Owing to such properties, two rare μ6-oxo centered mixed-valent, azide or acetate-bridged coordination polymers viz, [{MnII2MnIII10Na2(μ6-O)2(N3)10(NO3)(H2O)4(thme)8}·3(Et3NH)]n (1) and [{MnII3MnIII9Na7(μ2-O)2(μ6-O)2(O)5(CH3O)(CH3CO2)11(thmp)8}·4(O)]n (2), with retention of a Mn12 metallic core in both polymers are obtained using tripodal polyalcohol 1,1,1-tris (hydroxymethyl)ethane (H3thme) and 1,1,1-tris (hydroxymethyl)propane (H3thmp) ligands, respectively. X-ray analysis shows that 1 is a one-dimensional coordination polymer where Mn12 units are propagating by bridging azide function. 1 shows the underlying net of 2,2,3C6 topological type. 2 forms a cyclic ring as a result of repeating Mn12 zigzag chains bridging by sodium and H2O. The topology of 2 results in a 31-nodal...

A DFT study on the mechanism of rhodium-catalyzed regioselective hydrothiolation of the allyl amine

The reaction mechanisms of Rh-catalyzed regioselective hydrothiolation of the allyl amine employing four bidentate phosphine ligands are investigated with DFT calculations. The free energy profiles of anti-Markovnikov and Markovnikov pathways arising from different alkene insertion types are computed to elucidate the ligand-controlled regioselectivity. For 1,2-bis(diphenylphosphino)benzene (dppbz) and 1,3-bis(diphenylphosphino)propane (dppp) ligands with small nature bite angle (βn ≤ 86°), the anti-Markovnikov pathway that features the 1,2-alkene insertion into Rh-H bond is favored by 2 ˜ 4 kcal/mol in barriers of elementary steps. While for 1,4-bis(diphenylphosphino)butane (dppb) and bis(2-diphenylphosphinophenyl)ether (DPEphos) ligands with large nature bite angle (βn ≥ 99°), the Markovnikov pathway with 1,2-alkene insertion into Rh-S bond is preferential by 2 ˜ 7 kcal/mol in barriers. The P-Rh-P bite angle is a reliable predictor and regulator of the regioselectivity of reaction as evidenced by good correlations between reaction barrier and P-Rh-P bite angle. Smaller P-Rh-P bite angle in TSs is generally found for small nature bite angle ligand dppbz and dppp in preferential anti-Markovnikov pathway, while TSs with larger P-Rh-P bite angle are favored by large nature bite angle ligand DPEphos and dppb. Larger difference in P-Rh-P bite angles of TSs between Markovnikov and anti-Markovnikov pathway generally leads to the greater disparity in barrier heights of two pathways, and hence greater regiodivergency of reaction.