Hyperbranched polyester poly[3-(morpholin-4-yl)propionates] and their copper(II) complexes

Novel polydentate ligands on the basis of second- and third-generation hyperbranched polyesters containing terminal poly[3-(morpholin-4-yl)propionate] groups and their 6 : 1 and 13 : 1 polynuclear copper(II) complexes were synthesized. The degree of functionalization of the polyesters with morpholine increases in going from the second (56%) to third generation (68%). According to IR and electronic spectroscopy data, each coordination entity in the complexes is an isolated paramagnetic center of the formula CuN₂O₂Solv₂ (Solv = H₂O, DMSO).     

Synthesis and catalytic activities of Pd-phosphine complexes modified poly(ether imine) dendrimers

In this paper, we report synthesis of new alkyldiphenyl phosphine ligand modified poly(ether imine) dendrimers up to the third generation. The phosphinated dendrimers were obtained by functional group transformations of the alcohols present at the periphery of the dendrimers to chloride, followed by phosphination using LiPPh₂. The modification at the peripheries of the dendrimers was performed successfully to obtain up to 16 alkyl diphenylphosphines in the case of a third generation dendrimer, in good yields for each individual step. After phosphination, dendritic ligands were complexed with Pd(COD)Cl₂ to give dendritic phosphine-Pd^II complexes. Both the ligands and the metal complexes were characterized by spectroscopic and spectrometric techniques including high-resolution mass spectral analysis for the lower generations. Evaluation of the catalytic efficacies of the dendrimer-Pd^II metal complexes in mediating a prototypical C-C bond forming reaction, namely the Heck reaction, was performed using various olefin substrates. While the substrate conversion lowered with catalyst in the order from monomer to third generation dendrimer, the second and third generation dendrimers themselves were found to exhibit significantly better catalytic activities than the monomer and the first generation dendrimer.     

Hyperbranched bisphosphinoamine ligands: synthesis,characterization and application in ethylene oligomerization

Two hyperbranched bisphosphinoamine (PNP) ligands and chromium complexes were synthesized in good yield with 1.0 generation (1.0 G) hyperbranched macromolecules, chlorodiphenylphosphine (Ph₂PCl) and CrCl₃(THF)₃ as raw materials. The hyperbranched PNP ligands and chromium complexes were characterized by FT-IR, ¹H NMR, ³¹P NMR, UV and ESI-MS. Comparing with the chromium complexes, the hyperbranched PNP ligands, in combination with Cr(III), and activation by methylaluminoxane (MAO) in situ generated species with better catalytic performance for ethylene oligomerization. The effect of solvent, chromium source, ligand/Cr molar ratio, reaction temperature, Al/Cr molar ratio and reaction pressure on the catalytic activity and product selectivity were studied. The results showed that with increase of ligand/Cr molar ratio, reaction temperature and Al/Cr molar ratio, the catalytic activity increased at first and then decreased. However, the catalytic activity continuously increased with increase of reaction pressure. Under the optimized conditions, the catalytic system of hyperbranched PNP/Cr(III)/MAO led to catalytic activity of 2.68 × 10⁵ g/(mol Cr·h) and 37.71% selectivity for C₆ and C₈.     

Synthesis and characterization of mononuclear cadmium(II) and dinuclear uranyl(VI) complexes with <Emphasis Type="Italic">vic</Emphasis>-dioximes

In this study, the mononuclear complexes of cadmium(II) and dinuclear complexes of uranyl(VI) with five vic-dioximes have been obtained. Cadmium(II) forms, with ligands, complexes [(L ^xH)(Cl)(H₂O)(Cd)] with x=1–5. Mononuclear complexes with a metal: ligand ratio of 1:1 were obtained for cadmium(II) with the ligands, and a chloride ion and a water molecule are also coordinated to the cadmium(II) ions. Uranyl(VI) complexes of these ligands are a dinuclear structure with μ-hydroxo-bridges. Uranyl(VI) forms, with ligands, complexes [(L^xH)₂(OH)₂(UO₂)₂] with x=1–5, which have a 2:2 metal:ligand ratio. The structures of the complexes were identified by elemental analysis, i.r., and ¹H-n.m.r. spectra, u.v.–vis. spectroscopy, magnetic susceptibility measurements, conductivity measurements and thermogravimetric analysis (t.g.a.).     

Synthesis and properties of hyperbranched polyester polyacrylic acids and their metal complexes

New polydentate ligands based on the hyperbranched third generation polyesters containing terminal acrylic acid fragments were synthesized. The ionization and complexation parameters of new compounds in solution were estimated by spectrophotometry and pH-metric titration followed by experimental data processing using mathematical simulation by the CPESSP program. The procedure for the synthesis was proposed. The polynuclear cobalt(II), nickel(II), and copper(II) complexes with polyester polycarboxylates were synthesized.     

Biodegradable hyperbranched polyesters derived from 1,1,1‐tris(hydroxymethyl)ethane

Low molar mass hyperbranched polyesters were prepared by polycondensation of 1,1,1‐tris(hydroxymethyl)ethane and various dimethyl esters of aliphatic dicarboxylic acids in bulk. The usefulness of nontoxic bismuth salts as transesterification catalysts for these polycondensations was studied. The maximum conversion increased, and the reaction time decreased in the following sequence of increasing reactivity: dimethyl sebacate < adipate < glutarate < succinate. Regardless of the monomer combination, gelation occurred at conversions > 91.5%. The hyperbranched structure was proven by ¹H NMR spectroscopy and the absence of cyclic elements by MALDI‐TOF mass spectrometry. Quantitative acylation of all CH₂OH groups was achieved with an excess of acetic anhydride or methycrylic anhydride. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 231–238, 2009     

Iron(III)‐Complexes Engaged in the Biochemical Processes in Seawater. II. Voltammetry of Fe(III)‐Malate Complexes in Model Aqueous Solution

Characteristics of iron(III) complexes with malic acid in 0.55 mol L^?1 NaCl were investigated by voltammetric techniques. Three iron(III)‐malate redox processes were detected in the pH range from 4.5 to 11: first one at ?0.11 V, second at ?0.35 V and third at ?0.60 V. First process was reversible, so stability constants of iron(III) and iron(II) complexes were calculated: log K₁(Fe^III(mal))=12.66±0.33, log β₂(Fe^III(mal)₂)=15.21±0.25, log K₁(Fe^II(mal))=2.25±0.36, and log β₂(Fe^II(mal)₂)=3.18±0.32. In the case of second and third reduction process, conditional cumulative stability constants of the involved complexes were determined using the competition method: log β(Fe(mal)₂(OH)_x)=15.28±0.10 and log β(Fe(mal)₂(OH)_y)=27.20±0.09.     

Acid chloride‐functionalized hyperbranched polyester for facile and quantitative chain‐end modification: One‐pot synthesis and structure characterization

Carboxylic acid chloride end‐functionalized all‐aromatic hyperbranched polyesters were prepared from the bulk polycondensation of the AB₂ monomer 5‐(trimethylsiloxy)isophthaloyl dichloride. The acid chloride end functionality of the hyperbranched polyester was modified in situ with methanol and yielded methyl ester ends in a one‐pot process. Chain‐end functionalization and esterification were quantitative according to both potentiometric titration and ¹H NMR analysis. The signals of ¹H and ¹³C NMR spectra of the esterified hyperbranched polyester were fully assigned from model compounds of the focal, linear, dendritic, and terminal units. The degree of branching and molecular weight averages measured by ¹H and ¹³C NMR spectroscopy and multidetector size exclusion chromatography increased systematically with increasing polymerization temperatures between 80 and 200 °C. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2855–2867, 2002     

Synthesis,characterization, and antimicrobial activity of palladium(II) and platinum(II) complexes with 2‐substituted benzoxazole ligands

The synthesis and antimicrobial activity of palladium(II) and platinum(II) complexes derived from heterocyclic bidentate ligands, namely 2‐(2′‐aminophenyl)benzoxazole [L¹H₂], 2‐(2′‐hydroxyphenyl)benzoxazole [L²H], and 2‐(2′‐mercaptophenyl)benzoxazole [L³H], are reported here. These complexes have been characterized by elemental analyses, molecular weight determinations, conductance measurements, infrared, ¹H NMR, and electronic spectral studies. The resulting colored complexes are monomeric in nature. On the basis of above‐described studies, square‐planar geometry has been suggested for the resulting complexes. The ligands and their metal complexes were tested against certain microorganisms to assess their antimicrobial properties. The results indicate that the metal complexes are found more active than the parent ligands. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 21:44–50, 2010; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20578     

Selective ethylene oligomerization bearing hyperbranched bispyridylamine chromium catalyst

Two new hyperbranched bispyridylamine ligands and multinuclear chromium complexes were synthesized with 1.0?G hyperbranched macromolecules, 2-chloropyridine, 2-chloro-4-methylpyridine and CrCl₃(THF)₃ as raw materials. The structures of hyperbranched ligands and chromium complexes were characterized by UV, FT-IR, ¹H NMR, ESI-MS, and elemental analysis. These hyperbranched chromium complexes were evaluated as catalyst precursors by using MAO as activator in the oligomerization of ethylene. Effects of reaction temperature, reaction pressure, Al/Cr molar ratio, concentration of catalyst, solvent, and the structure of catalysts on the catalytic activity and product selectivity were investigated. The oligomerization results showed that with increase of reaction temperature, reaction pressure, and Al/Cr molar ratio, the catalytic activity increased and then decreased; the catalytic activity continuously decreased as the amount of catalyst increased. The products were mainly based on C₆ and C₈. Under optimized conditions, the catalytic system of hyperbranched NNN/Cr(III)/MAO led to activity of 1.26?×?10⁵ g/(mol·Cr·h) and 63.34% selectivity for C₆ and C₈.     

A MALDI‐TOF MS study of lanthanide(III)‐cored poly(phenylenevinylene) dendrimers

An extensive study by matrix‐assisted laser desorption/ionization time‐of‐flight (MALDI‐TOF) mass spectrometry (MS) of some first‐generation and second‐generation lanthanide(III)‐cored poly(phenylenevinylene) dendrimers is described. The complexes were obtained by self‐assembly of suitably functionalized carboxylate dendrons around the lanthanide ion (La³⁺, Er³⁺). Fourier transform infrared (FT‐IR) spectroscopy gave reasonable evidence for the proposed structures. However, MS was used to ascertain unequivocally the complex formation. The most reliable results were found in the negative reflector mode, using 2‐[(2E)‐3‐(4‐tert‐butylphenyl)‐2‐methylprop‐2‐enylidene]malononitrile (DCTB) as matrix. Well‐defined and highly resolved base peaks corresponding to negative ions of [Gn₄La]^? and [Gn₄Er]^? were found in all cases, with an excellent match between the theoretical and observed isotope distributions. However, the 3 : 1 stoichiometry used in the synthesis guarantees an empirical formula Gn₃Ln for the complexes. Copyright © 2008 John Wiley & Sons, Ltd.     

SYNTHESIS AND STEREOCHEMISTRY OF PENTACARBONYL(PHOSPHOLE)METAL(0)- AND TETRACARBONYLBIS(PHOSPHOLE)METAL(0) COMPLEXES OF 6B ELEMENTS

Abstract

Pentacarbonylphospholemetal(0) and cis-tetracarbonylbis(phosphole)metal(0) complexes were synthesized from the thermal reaction of M(CO)₃(THF) and M(CO)₄(COD) (M: Cr, Mo, W) with corresponding phosphole (1-phenyl-3,4-dimethylphosphole, 1-phenyl-3-methylphosphole, and 1-phenylphosphole). These complexes were isolated as orange crystals by column chromatography on silicagel at 253 K and crystallization from n-hexane at 223 K and characterized by means of IR and NMR (¹H, ¹³C, and ³¹P). Spectroscopic data shows that the phosphole is coordinated to the transition metal through its phosphorus atom rather than through the conjugated diene unit in the both types of complexes. The tetracarbonylbis(phosphole)metal(0) complexes were found to have cis-arrangement of two phosphole ligands. Comparing ¹³C-NMR chemical shifts of the complexes with the free ligands, one can deduce that the involvement of the phosphorus atom in the ring π-electron delocalization is drastically reduced upon coordination. This is attributed to the stronger [sgrave]-donation but weaker π-accepting ability of the phosphorus atom in the phosphole ligands compared to the carbonyl groups.     

Synthesis and characterization of ruthenium(ii) complexes of 5-hydroxyflavones

Bis(dimethyl sulfoxide)bis(flavonato)ruthenium(II) complexes, RuL₂(DMSO)₂, were synthesized by the reaction of dichlorotetrakis(dimethyl sulfoxide)ruthenium(II) with the sodium salts of 5-hydroxyflavone, 5-hydroxy-4′-methoxyflavone and 5-hydroxy-3′,4′,5′,7-tetramethoxyflavone, ( L ). The complexation was followed by ¹H nmr spectroscopy. The 1:1 kinetically favoured tris(dimethyl sulfoxide)chloroflavonatoruthenium(II) complexes, RuLCl(DMSO)₃, were initially formed and then transformed into the thermodynamically more stable ones. Each one of these complexes, by reacting with another equivalent of lig-and L, also gave rise to a mixture of 1:2 kinetic species, from which the 1:2 thermodynamically more stable bis(dimethyl sulfoxide)bis(flavonato)ruthenium(II) complexes, RuL₂(DMSO)₂, were formed. The complexes were characterized by extensive studies involving ¹H, ¹³C nuclear magnetic resonance, infrared and ultraviolet-visible spectroscopy, mass spectrometry, cyclic voltammetry and elemental analysis. Such 1:2 complexes exhibited properties of two nonequivalent flavonate ligands and also of two non-equivalent dimethyl sulfoxide ligands; one of these dimethyl sulfoxide ligands is considered to be S-bonded and the other O-bonded. Also two quasireversible one-electron redox steps were observed at 0.53 to 0.57 and 0.44 to 0.41 V (vs Saturated Calomel Electrode). The spectroscopic results obtained allow for the discussion of stereochemistry of each bis(dimethyl sulfoxide)bis(flavonato)ruthenium(II) complex and to postulate its possible structure as one corresponding to the more anisochronous species.     

Synthesis and characterization of new (<Emphasis Type="Italic">E,E</Emphasis>)-dioximes and their divalent metal complexes

Two new soluble vic-dioxime ligands, 4-isopropylanilineglyoxime (L¹H₂) and 4-benzylpiperidineglyoxime (L²H₂) were prepared by reacting 4-isopropylaniline and 4-benzylpiperidine with anti-chloroglyoxime. Ten metal complexes were obtanied by reacting both ligands with Cu(II),Ni(II),Co(II), Zn(II), and Cd(II) cations. The ligands and their metal complexes were elucidated by elemental analysis, IR, UV-vis, ¹H NMR, and ¹³C NMR and also magnetic moments of the complexes were determined. The text was submitted by the authors in English.     

Synthesis and characterization of new complexes of the type [Ru(CO)2Cl2 (2‐phenyl‐1,8‐naphthyridine‐kN) (2‐phenyl‐1,8‐naphthyridine‐kN′)]. Preliminary applications in homogeneous catalysis

Novel ruthenium (II) complexes were prepared containing 2‐phenyl‐1,8‐naphthyridine derivatives. The coordination modes of these ligands were modified by addition of coordinating solvents such as water into the ethanolic reaction media. Under these conditions 1,8‐naphthyridine (napy) moieties act as monodentade ligands forming unusual [Ru(CO)₂Cl₂(η¹‐2‐phenyl‐1,8‐naphthyridine‐ kN )(η¹‐2‐phenyl‐1,8‐naphthyridine‐kN′)] complexes. The reaction was reproducible when different 2‐phenyl‐1,8‐naphthyridine derivatives were used. On the other hand, when dry ethanol was used as the solvent we obtained complexes with napy moieties acting as a chelating ligand. The structures proposed for these complexes were supported by NMR spectra, and the presence of two ligands in the [Ru(CO)₂Cl₂(η¹‐2‐phenyl‐1,8‐naphthyridine‐ kN )(η¹‐2‐phenyl‐1,8‐naphthyridine‐kN′)] type complexes was confirmed using elemental analysis. All complexes were tested as catalysts in the hydroformylation of styrene showing moderate activity in N,N′‐dimethylformamide. Copyright © 2008 John Wiley & Sons, Ltd.     

Insights into Functional‐Group‐Tolerant Polymerization Catalysis with Phosphine–Sulfonamide Palladium(II) Complexes

Two series of cationic palladium(II) methyl complexes {[(2‐MeOC₆H₄)₂PC₆H₄SO₂NHC₆H₃(2,6‐R¹,R²)]PdMe}₂[A]₂ ( ^X 1⁺‐A : R¹=R²=H: ^H 1⁺‐A ; R¹=R²=CH(CH₃)₂: ^DIPP 1⁺‐A ; R¹=H, R²=CF₃: ^CF3 1⁺‐A ; A =BF₄ or SbF₆) and neutral palladium(II) methyl complexes {[(2‐MeOC₆H₄)₂PC₆H₄SO₂NC₆H₃(2,6‐R¹,R²)]PdMe(L)} ( ^X 1‐acetone : L=acetone; ^X 1‐dmso : L=dimethyl sulfoxide; ^X 1‐pyr : L=pyridine) chelated by a phosphine–sulfonamide were synthesized and fully characterized. Stoichiometric insertion of methyl acrylate (MA) into all complexes revealed that a 2,1 regiochemistry dominates in the first insertion of MA. Subsequently, for the cationic complexes ^X 1⁺‐A , β‐H elimination from the 2,1‐insertion product ^X 2⁺‐A_MA‐2,1 is overwhelmingly favored over a second MA insertion to yield two major products ^X 4⁺‐A_MA‐1,2 and ^X 5⁺‐A_MA . By contrast, for the weakly coordinated neutral complexes ^X 1‐acetone and ^X 1‐dmso , a second MA insertion of the 2,1‐insertion product ^X 2_MA‐2,1 is faster than β‐H elimination and gives ^X 3_MA as major products. For the strongly coordinated neutral complexes ^X 1‐pyr , no second MA insertion and no β‐H elimination (except for ^DIPP 2‐pyr_MA‐2,1 ) were observed for the 2,1‐insertion product ^X 2‐pyr_MA‐2,1 . The cationic complexes ^X 1⁺‐A exhibited high catalytic activities for ethylene dimerization, affording butenes (C₄) with a high selectivity of up to 97.7 % (1‐butene: 99.3 %). Differences in activities and selectivities suggest that the phosphine–sulfonamide ligands remain coordinated to the metal center in a bidentate fashion in the catalytically active species. By comparison, the neutral complexes ^X 1‐acetone , ^X 1‐dmso , and ^X 1‐pyr showed very low activity towards ethylene to give traces of oligomers. DFT analyses taking into account the two possible coordination modes (O or N) of the sulfonamide ligand for the cationic system ^CF3 1⁺ suggested that the experimentally observed high activity in ethylene dimerization is the result of a facile first ethylene insertion into the O‐coordinated PdMe isomer and a subsequent favored β‐H elimination from the N‐coordinated isomer formed by isomerization of the insertion product. Steric hindrance by the N‐aryl substituent in the neutral systems ^CF3 1 and ^H 1 appears to contribute significantly to a higher barrier of insertion, which accounts for the experimentally observed low activity towards ethylene oligomerization.     

Synthesis,spectroscopic and electrochemical studies of copper(II) and cobalt(II) complexes of three unsymmetrical vic -dioximes ligands

Cobalt(II) and copper(II) complexes with three dioxime ligands cyclohexylamine-p-tolylglyoxime (L₁H₂), tert-butyl amine-p-tolylglioxime (L₂H₂) and sec-butylamine-p-tolylglyoxime (L₃H₂), have been prepared. The metal to ligand ratios of the complexes were found to be 1?:?2. The Cu(II) complexes of these ligands are proposed to be square planar; the Co(II) complexes are proposed to be octahedral with water molecules as axial ligands. Ligands and complexes are soluble in common solvents such as DMSO, DMF, CHCl₃ and C₂H₅OH. The ligands have been characterized by elemental analysis, IR, UV-VIS, ¹H?NMR, ¹³C?NMR and thermogravimetric analysis (TGA). The complexes were characterized by elemental analysis, IR, UV-VIS, magnetic susceptibility measurements, thermogravimetric analysis (TGA) and electrochemistry. Electrochemical properties of metal complexes show quasi-reversible one-electron redox processes. However, Co(L₁H)₂ and Cu(L₁H)₂ complexes show another oxidation peak in the positive region. This single irreversible oxidation peak is caused by the cyclic ring of the ligand. Data also revealed that the electron transfer rates of metal complexes with L₁H₂ are higher than the other complexes.     

Synthesis, Spectroscopic and Electrochemical Investigations of Two vic-Dioximes and Their Mononuclear Ni（Ⅱ）, Cu（Ⅱ） and Co（Ⅱ） Metal Complexes Containing Morpholine Group

Two vic-dioxime ligands （LxH2） containing morpholine group have been synthesized from 4-[2-（dimethylaminoethyl）] morpholine with anti-phenylchloroglyoxime or anti-monochloroglyoxime in absolute THF at -15 ℃. Reaction of two vic-dioxime ligands with MCl2·nH2O （M： Ni, Cu or Co and n=2 or 6） salts in 1 ： 2 molar ratio afforded metal complexes of type [M（LxH）2] or [M（LxH）2·2H2O]. All of metal complexes are non-electrolytes as shown by their molar conductivities （Am） in DMF （dimethyl formamide） at 10^-3 mol·L^-1. Structures of the ligands and metal complexes have been solved by elemental analyses, FT-IR, UV-Vis, ^1H NMR and ^13C NMR, magnetic susceptibility measurements, molar conductivity measurements. Furthermore, redox properties of the metal complexes were investigated by cyclic voltammetry.     

Formation of a polynuclear cobalt(ii) complex on a polydentate nanoplatform of carboxylated boltorn H20

A method of synthesis of a polynuclear cobalt(II) complex with carboxylated Boltorn H20, a hyperbranched polyol of second generation, has been suggested. The logarithm of stability constant and the composition of the complex species BH20(OC(O)CH₂CH₂COO)₁₂Co₁₂ in a 50% acetone solution have been calculated from the electronic absorption spectra: log?? = 13.7 ± 0.2 and the composition M : L = 12 : 1. The IR spectroscopy and NMR (¹³C and ¹H) point to the coordination of Co(II) ions not only at the surface of the molecule but also near its core.     

Copper(II) and zinc(II) complexes of thiophene/furan carboxamides: Synthesis,structure and properties

Cu(II) and Zn(II) complexes were synthesized from equimolar amounts of carboxamides; 1,8-bis(2-thiophenecarboxamido)-p-menthane (tkdam) and 1,8-bis(2-furancarboxamido)-p-menthane (furdam). The structure of the carboxamides were determined by elemental analysis; ¹H NMR, ¹³C NMR, FT-IR and LC-MS spectra. The relative energies and the electronic properties (LUMO, HOMO, LUMO-HOMO gap) of the ligands were investigated theoretically by performing Semi-empirical molecular orbital theory PM3 method in Hyperchem 7 (Release). Carboxamide complexes having general formula as; monomeric, [ML]Cl₂ and dimeric [Cu(tkdam)Cl]₂Cl₂ · 5H₂O were synthesized and characterized by using element analysis; FT-IR, LC-MS spectra; magnetic susceptibility, molar conductivity and thermal (TGA/DTA curve) studies. It was found that the coordination number of the monomeric complexes is four whereas dimeric’s is six. The changes in the selected vibration bands in FT-IR indicate that, carboxamides behave as tetradentate ligands and coordinate to metal ions from acyl ring (through S/O) and amide carbonyl (C=O). Molar conductivity measurements indicate the 1: 2 ionic nature of the carboxamide complexes.