Synthesis,spectroscopic characterisation and structure of the first chiral heteroleptic bis(phthalocyaninato) rare earth complexes

Treatment of MIII(Pc)(acac) (M = Sm, Eu, Gd; Pc = phthalocyaninate; acac = acetylacetonate), generated in situ, with 3-(3-pentyloxy)phthalonitrile in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in n-pentanol affords racemic mixtures of the chiral double-deckers MIII(Pc)[Pc(OC5H11)4] [Pc(OC5H11)4 = 1,8,15,22-tetrakis(3-pentyloxy)phthalocyaninate], which have been spectroscopically and structurally characterised.     

Heteroleptic bis(phthalocyaninato) europium(III) complexes fused with different numbers of 15-crown-5 moieties. Synthesis, spectroscopy, electrochemistry, and supramolecular structure

A series of heteroleptic bis(phthalocyaninato) europium(III) complexes, namely, Eu(Pc)[Pc(15C5)] (2), Eu(Pc)[Pc(opp-15C5)2] (3), Eu(Pc)[Pc(adj-15C5)2] (4), Eu(Pc)[Pc(15C5)3] (5), and Eu(Pc)[Pc(15C5)4] (6) [Pc = unsubstituted phthalocyaninate; Pc(15C5) = 2,3-(15-crown-5)phthalocyaninate; Pc(opp-15C5)2 = 2,3,16,17-bis(15-crown-5)phthalocyaninate; Pc(adj-15C5)2 = 2,3,9,10-bis(15-crown-5)phthalocyaninate; Pc(15C5)3 = 2,3,9,10,16,17-tris(15-crown-5)phthalocyaninate, Pc(15C5)4 = 2,3,9,10,16,17,24,25-tetrakis(15-crown-5)phthalocyaninate], with one, two, three, and four 15-crown-5 voids attached at different positions of one of the two phthalocyaninato ligands in the double-decker molecules, have been devised and prepared by Eu(Pc)(acac)-induced (Hacac = acetylacetone) mixed cyclization of the two corresponding phthalonitriles in the presence of organic base 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in n-pentanol. For the purpose of comparative studies, homoleptic counterparts Eu(Pc)2 (1) and Eu[Pc(15C5)4]2 (7) have also been prepared. These sandwich double-decker complexes have been characterized by a wide range of spectroscopic methods in addition to elemental analysis. Their electrochemistry has also been studied by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The molecular structure of Eu(Pc)[Pc(15C5)4] (6) has been determined by X-ray diffraction analysis. Their supramolecular structure-formation properties, in particular for compounds 5 and 6 in the presence of potassium ions, have also been comparatively studied for the purpose of future functional investigation.     

New trinuclear carbonato-bridged copper(II) complexes: Synthesis,crystal structure,and spectroscopic properties

New trinuclear carbonato-bridged copper(II) complexes, [Cu₃(Bipy)₆(μ₃-CO₃)](CF₃SO₃)₄(H₂O)_0.5 (I) and [Cu₃(Phen)₆(μ₃-CO₃)](CF₃SO₃)₄(H₂O)_0.5 (II) (Bipy = 2,2′-bipyridine and Phen = 1,10-phenanthroline), have been synthesized and characterized by X-ray crystallography. In the trinuclear units, a carbonate anion triply bridges three Cu atoms in a μ₃-η¹:η¹:η¹-CO₃ mode. The environment around each copper(II) center is five-coordinate ranging between intermediate to distorted square-pyramidal geometry. In the crystal packing, the molecule of I is involved in a variety of intra/intermolecular non-covalent interactions such as intra/intermolecular stacking and CH···π interactions between the pyridine groups of the chelated ligand, leading to a one-dimensional arrangement of I. In complex II, the molecule is involved in both intra- and intermolecular Phen-Phen π-stacking, forming a three-dimensional network. The spectroscopic (IR, diffuse reflectance, and EPR spectra) properties and the preliminary results of magnetic measurements of both complexes are investigated and compared to other closely related trinuclear copper(II) complexes.     

Synthesis,structure and spectroscopic properties of some thiosemicarbazone complexes of platinum

Reaction of salicyldehyde thosemicarbazone (H₂L¹), 2-hydroxyacetophenone thiosemicarbazone (H₂L²) and 2-hydroxynapthaldehyde thiosemicarbazone (H₂L³) (general abbreviation H₂L, where H₂ stands for the two dissociable protons, one phenolic proton and one hydrazinic proton) with K₂[PtCl₄] afforded a family of polymeric complexes of type [{Pt(L)}_n]. Reaction of the polymeric species with two monodentate ligands (D), viz. triphenylphosphine (PPh₃) and 4-picoline (pic), yielded complexes of the type [Pt(L)(D)]. These mixed-ligand complexes were also obtained from the reaction of the thiosemicarbazones with [Pt(PPh₃)₂Cl₂] and [Pt(pic)₂Cl₂]. The crystal structure of [Pt(PPh₃)(L²)] has been determined. The thiosemicarbazone ligands are coordinated, via dissociation of the two protons, as dianionic tridentate O,N,S-donors. The [Pt(L)(D)] complexes show characteristic ¹H NMR spectra and intense absorptions in the visible and ultraviolet region. They also fluoresce in the visible region at ambient temperature.     

Synthesis, structure, spectroscopic properties, electrochemistry, and DFT correlative studies of N-[(2-pyridyl)methyliden]-6-coumarin complexes of Cu(I) and Ag(I)

6-Aminocoumarin reacts with pyridine-2-carboxaldehyde and has synthesized N-[(2-pyridyl)methyliden]-6-coumarin (L). The ligand, L, reacts with [Cu(MeCN)₄]ClO₄/AgNO₃ to synthesize Cu(I) and Ag(I) complexes of formulae, [Cu(L)₂]ClO₄ and [Ag(L)₂]NO₃, respectively. While similar reaction in the presence of PPh₃ has isolated [Cu(L)(PPh₃)₂]ClO₄ and [Ag(L)(PPh₃)₂]NO₃. All these compounds are characterized by FTIR, UV-Vis and ¹H NMR spectroscopic data. In case of [Cu(L)(PPh₃)₂]ClO₄ and [Ag(L)(PPh₃)₂]NO₃, the structures have been confirmed by X-ray crystallography. The structure of the complexes are distorted tetrahedral in which L coordinates in a N,N′ bidentate fashion and other two coordination sites are occupied by PPh₃. The ligand and the complexes are fluorescent and the fluorescence quantum yields of [Cu(L)(PPh₃)₂]ClO₄ and [Ag(L)(PPh₃)₂]NO₃ are higher than [Cu(L)₂]ClO₄ and [Ag(L)₂]NO₃. Cu(I) complexes show Cu(II)/Cu(I) quasireversible redox couple while Ag(I) complexes exhibit deposition of Ag(0) on the electrode surface during cyclic voltammetric experiments. gaussian 03 computations of representative complexes have been used to determine the composition and energy of molecular levels. An attempt has been made to explain solution spectra and redox properties of the complexes.     

Structures and properties of 1,8,15,22-tetrasubstituted phthalocyaninato-lead complexes: the substitutional effect study based on density functional theory calculations

Density functional theory (DFT) and time-dependent DFT calculations were carried out to comparatively describe the molecular structures, molecular orbital energy gaps, atomic charges, infrared (IR) and Raman spectra, and UV-vis spectra of PbPc (1), PbPc(alpha-OC2H5)4 (2), and PbPc(alpha-OC5H11)4 (3) {Pc2- = dianion of phthalocyanine; [Pc(alpha-OC2H5)4]2- = dianion of 1,8,15,22-tetra-ethoxyphthalocyanine; [Pc(alpha-OC5H11)4]2- = dianion of 1,8,15,22-tetrakis(3-pentyloxy)phthalocyanine}. The calculated structural data of compounds 1 and 3 and the simulated IR and UV-vis spectra of 3 are compared with X-ray crystallography molecular structures and the experimental absorption spectra respectively to verify the performance of the B3LYP method and the LANL2DZ basis set. Substitution of bulky alkoxy groups at the nonperipheral positions of the phthalocyanine ring adds obvious effect to the molecular structure of phthalocyaninato lead compounds by deflecting the isoindole units in the direction that the isoindole units extends and distorting them in the C4 axis direction due to the steric hindrance. Both the calculated IR and UV-vis absorption spectra of 3 correspond well with the experimental results.     

Synthesis, structure, spectroscopic properties, and electrochemical oxidation of ruthenium(II) complexes Incorporating monocarboxylate bipyridine ligands

[Ru(bpy)(2)(Mebpy-COOH)](PF(6))(2).3H(2)O (1), [Ru(phen)(2)(Mebpy-COOH)](ClO(4))(2).5H(2)O (2), [Ru(dppz)(2)(Mebpy-COOH)]Cl(2).9H(2)O (3), and [Ru(bpy)(dppz)(Mebpy-COOH)](PF(6))(2).5H(2)O (4) (bpy = 2,2'-bipyridine, Mebpy-COOH = 4'-methyl-2,2'-bipyridine-4-carboxylic acid, phen = 1,10-phenanthroline, dppz = dipyrido[3,2,-a;2',3-c]phenazine) have been synthesized and characterized spectroscopically and by microanalysis. The [Ru(Mebpy-COOH)(CO)(2)Cl(2)].H(2)O intermediate was prepared by reaction of the monocarboxylic acid ligand, Mebpy-COOH, with [Ru(CO)(2)Cl(2)](n), and the product was then reacted with either bpy, phen, or dppz in the presence of an excess of trimethylamine-N-oxide (Me(3)NO), as the decarbonylation agent, to generate 1, 2, and 3, respectively. For compound 4, [Ru(bpy)(CO)Cl(2)](2) was reacted with Mebpy-COOH to yield [Ru(bpy)(Mebpy-COOH)(CO)Cl](PF(6)).H(2)O as a mixture of two main geometric isomers. Chemical decarbonylation in the presence of dppz gave 4 also as a mixture of two isomers. Electrochemical and spectrophotometric studies indicated that complexes 1 and 2 were present as a mixture of protonated and deprotonated forms in acetonitrile solution because of water of solvation in the isolated solid products. The X-ray crystal structure determination on crystals of [Ru(bpy)2(MebpyCOO)][Ru(bpy)(2)(MebpyCOOH)](3)(PF(6))(7), 1a, and [Ru(phen)(2)(MebpyCOO)](ClO(4)).6H(2)O, 2a, obtained from solutions of 1 and 2, respectively, revealed that 1a consisted of a mixture of protonated and deprotonated forms of the complex in a 1:3 ratio and that 2a consisted of the deprotonated derivative of 2. A distorted octahedral geometry for the Ru(II) centers was found for both complexes. Upon excitation at 450 nm, MeCN solutions of the protonated complexes 1-4 were found to exhibit emission bands in the 635-655 nm range, whereas the corresponding emission maxima of their deprotonated forms were observed at lower wavelengths. Protonation/deprotonation effects were also observed in the luminescence and electrochemical behavior of complexes 1-4. Comprehensive electrochemical studies in acetonitrile show that the ruthenium centers on 1, 2, 3, and 4 are oxidized from Ru(II) to Ru(III) with reversible potentials at 917, 929, 1052, and 1005 mV vs Fc(0/+) (Fc = ferrocene), respectively. Complexes 1 and 2 also exhibit an irreversible oxidation process in acetonitrile, and all compounds undergo ligand-based reduction processes.     

Synthesis, electrochemistry, and spectroscopic characterization of bis-dirhodium complexes linked by axial ligands

The synthesis and electrochemical and spectroscopic properties of bis-dirhodium complexes containing ap or dpf bridging ligands, (ap)(4)Rh(2)(C triple bond C)(2)Rh(2)(ap)(4) (2) and (dpf)(4)Rh(2)(CNC(6)H(4)NC)Rh(2)(dpf)(4) (4), were investigated (where ap and dpf are the 2-anilinopyridinate and N,N'-diphenylformamidinate ions, respectively). The related "simple" dirhodium species, (ap)(4)Rh(2)(C triple bond C)(2)Si(CH(3))(3) (1) and (dpf)(4)Rh(2)(CNC(6)H(5)) (3), with the same set of bridging ligands were also synthesized and their properties compared to those of the analogous bis-dirhodium complexes. Compound 1 was obtained by mixing (ap)(4)Rh(2)Cl and Li(C triple bond C)(2)Si(CH(3))(3) in refluxing THF for 16 h under vacuum while compound 2 was prepared by a reaction between (ap)(4)Rh(2)(C triple bond C)(2)Li and (ap)(4)Rh(2)Cl under similar conditions. The reaction between (CF(3)COO)(4)Rh(2) and molten Hdpf under vacuum for 24 h leads to the generation of compound 3 with a yield of 65%. The red-orange compound 4 was obtained upon addition of 0.5 equiv of CNC(6)H(4)NC at room temperature to a CH(2)Cl(2) solution containing (dpf)(4)Rh(2) which was synthesized according to a method described previously in the literature. Compound 1 crystallizes in the triclinic space group P1, with a = 10.164(3) A, b = 13.881(3) A, c = 18.805(4) A, alpha = 73.55(2) degrees, beta = 77.89(2) degrees, gamma = 84.85(2) degrees, and Z = 2. Crystals of 2 were not good enough to collect adequate data for X-ray analysis, but the identity of this compound was confirmed, along with its P1; space group. Crystals of 3 and 4 belong to the monoclinic, P2(1)/c space group and the triclinic, P1; space group, respectively, with a = 13.5254(5) A, b = 13.7387(4) A, c = 27.2011(12) A, beta = 102.637(2) degrees, and Z = 4 for 3 and a = 13.866(8) A, b = 14.756(7) A, c = 15.008(6) A, alpha = 79.91(3) degrees, beta = 87.72(4) degrees, gamma = 89.19(4) degrees, and Z = 1 for 4. Compound 1 exhibits a single reversible oxidation at E(1/2) = 0.66 V and a single reversible reduction at E(1/2) = -0.44 V vs SCE in THF, 0.2 M TBAP. Both processes involve a one-electron transfer. Compound 2 undergoes a reversible oxidation at E(1/2) = 0.60 V and two separate one-electron-transfer reductions at E(1/2) = -0.52 and -0.65 V in THF, 0.2 M TBAP. The oxidation involves two overlapped one-electron-transfer processes. Compounds 3 and 4 undergo two reversible oxidations in CH(2)Cl(2), 0.1 M TBAP located at E(1/2) = 0.23 and 1.22 V (3) or 0.22 and 1.20 V (4). Each redox reaction of 3 involves a one-electron-transfer step while each redox reaction of 4 involves two overlapping one-electron transfers. Compound 2 shows interaction between the two dirhodium cores upon reduction, while 4 gives no evidence of electronic interaction between the two dirhodium units during either reduction or oxidation. An ESR signal with axial symmetry was obtained for the neutral compounds 1 and 2, and a similar spectrum was obtained for the singly oxidized products of compounds 3 and 4, thus suggesting the electronic configuration of (sigma)(2)(pi)(4)(delta)(2)(pi)(4)(delta)(1) for the neutral compounds 1 and 2 as well as for the oxidized compounds 3 and 4. The four compounds were also characterized by FTIR and UV-visible spectroscopy as well as by mass spectrometry.     

Studies of "pinwheel-like" bis[1,8,15,22-tetrakis(3-pentyloxy)phthalocyaninato] rare earth(III) double-decker complexes

Homoleptic bis(phthalocyaninato) rare-earth double-deckers complexes [M(III)[Pc(alpha-OC5H11)4]2] (M = Eu, Y, Lu; Pc(alpha-OC5H11)4 = 1,8,15,22-tetrakis(3-pentyloxy)phthalocyaninate) have been prepared by treating the metal-free phthalocyanine H2Pc(alpha-OC5H11)4 with the corresponding M(acac)3.nH2O (acac = acetylacetonate) in refluxing n-octanol. Due to the C4h symmetry of the Pc(alpha-OC5H11)4 ligand and the double-decker structure, all the reactions give a mixture of two stereoisomers with C4h and D4 symmetry. The former isomer, which is a major product, can be partially separated by recrystallization due to its higher crystallinity. The molecular structure of the major isomer of the Y analogue has been determined by single-crystal X-ray diffraction analysis. The metal center is eight-coordinate bound to the isoindole nitrogen atoms of the two phthalocyaninato ligands, forming a distorted square antiprism. Such an arrangement leads to an interesting pinwheel structure when viewed along the C4 axis, which assumes a very unusual S8 symmetry. The major isomers of all these double-deckers have also been characterized with a wide range of spectroscopic methods. A systematic investigation of their electronic absorption and electrochemical data reveals that the pi-pi interaction between the two Pc(alpha-OC5H11)4 rings is weaker than that for the corresponding unsubstituted or beta-substituted bis(phthalocyaninato) analogues.     

Synthesis,spectroscopic properties and crystal structure of the eight-coordinated lead complex bis[thiocyanato]-1,4,7,10,13-pentaoxacyclopentadecano lead(II)

The complex [Pbc[15]crown-5](SCN)₂ was synthesized and characterized spectroscopically (IR and FIR range) and the crystal structure was determined by X-ray diffraction on a single crystal (orthorhombic space group Pmc2₁). The structure was solved by Patterson synthesis with least-square refinement. The final R-value is 0.0328. Two Pb-atoms and two unidentical halves of the ligand were found in the asymmetric unit. For each complexed lead cation and each half of the crown ether there exists a plane of reflexion, whereby C18 and C28 are disordered. There is, however, no centre of inversion between these unidentical halves. The elementary cell comprises four units and two different types of two centrally coordinated Pb cations. Both lead cations are eight-coordinated. In the case of Pb1 the eight donor centres are the five O-atoms of the ligand and three N-atoms of the thiocyanates. For Pb2 these are five oxygens of the ligand, one nitrogen and two sulphurs of the three thiocyanates. In this complex the thiocyanate ligands occur in both ionic and covalent states. The complexation of the crown ether and the two different species of thiocyanate anions are indicated too by typical shifted absorption bands in the IR spectra. The vibrations in the FIR region can be assigned to the interactions between lead and the donor groups.     

Synthesis,binding properties and electrochemistry of nickel(II) macrocyclic complexes containing crown ethers

Macrotetracyclic complexes of nickel(II) containing crown ethers as pendant arms, [Ni(B)](ClO₄)₂ and [Ni(C)](ClO₄)₂, were prepared and characterized. The binding constants of the complexes toward alkali metal ions are relatively small compared with those of free 15-crown-5 or 18-crown-6 and the reduction potentials of the [Ni(B)](ClO₄)₂ and [Ni(C)](ClO₄)₂ in the presence of alkali metal ions shift to the positive direction in the order Li⁺>Na⁺>K⁺ and K⁺>Na⁺>Li⁺, respectively.     

Synthesis,spectroscopic properties,crystal structure and biological activities of copper(II) 2-methylthionicotinate complexes with furopyridines

The synthesis and characterization of six new 2-methylthionicotinate (2-MeSnic) copper(II) monomeric complexes [Cu(2-MeSnic)₂L₂] (L is furo[3,2-c]pyridine—fpy, 2-methylfuro[3,2-c]pyridine—Mefpy, 2,3-dimethylfuro[3,2-c]pyridine—Me₂fpy or benzo[4,5]furo[3,2-c]pyridine—Bfp), [Cu(2-MeSnic)₂(fpy)₂(H₂O)], as well as [Cu(2-MeSnic)₂(CF₃Phfpy)₂(H₂O)₂] (CF₃Phfpy is 2-(3-trifluoromethylphenyl)furo[3,2-c]pyridine) are reported. The characterizations were based on elemental analysis, infrared, electronic and EPR spectra. The crystal structure of one of the complexes has been determined. The Cu^II atoms of [Cu(2-MeSnic)₂(fpy)₂(H₂O)] are six-coordinated in a highly distorted tetragonal–bipyramidal arrangement by two nitrogen atoms, one from each fpy, in trans-positions, by three oxygen atoms of the carboxyl groups of 2-MeSnic ligands (one monodentate, one asymmetrically bidentate), one axial position being occupied by the oxygen of a water molecule. The antimicrobial effects have been tested on various strains of bacteria, yeasts and filamentous fungi. A comparison of the IC₅₀ and MIC values has shown a decrease of inhibition activities of tested compounds in the order: [Cu(2-MeSnic)₂(Bfp)₂] > Bfp > [Cu(2-MeSnic)₂(CF₃Phfpy)₂(H₂O)₂] > [Cu(2-MeSnic)₂(Me₂fpy)₂] > CF₃Phfpy > [Cu(2-MeSnic)₂(Mefpy)₂] > Me₂fpy > [Cu(2-MeSnic)₂(fpy)₂(H₂O)] > [Cu(2-MeSnic)₂(H₂O)]₂ > Mefpy > fpy = 2-MeSnicH = CuSO₄. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Ir(I)–carbonyl complexes of coumarinazoimidazoles: Synthesis structure, electrochemistry, photophysical properties and DFT calculations

The reactions of Vaska’s complex [IrCl(CO)(PPh₃)₂] with 2-(coumaryl-6-azo)imidazole (CZ-H) and its derivatives (CZ-X) have synthesized [Ir(CZ)(CO)(PPh₃)₂] and [Ir(CZ-X)(CO)(PPh₃)₂]. All the complexes have been characterized by FT-IR, UV-Vis, ¹H NMR and FAB-MS spectroscopy. The structural confirmation has been done in one case, by a single crystal X-ray diffraction study, which shows a distorted square pyramidal geometry around the central Ir atom. The complexes are emissive at room temperature. The cyclic voltammetry of the complexes shows a metal centered irreversible oxidation and ligand centered quasireversible reduction couples. To get an insight into the electronic structure, absorption spectra and electrochemical properties, detailed calculations on all three complexes have been performed at the DFT level.     

Synthesis, spectroscopic properties and crystal structure of mononuclear tricarbonylrhenium(I) chloride complexes carrying 6-functionalised quinoxalines

Two quinoxaline derivatives pqCH₃ and pqCl (where pq stands for 2-(2′-pyridyl)quinoxaline) were prepared by condensation of 2-acetyl pyridyl with 2-amino-4-methylphenylamine or 2-amino-4-chlorophenylamine, correspondingly and were studied spectroscopically and electrochemically, in correlation with the originally reported pq. Their novel corresponded complexes namely, fac-[Re(CO)₃Cl(L)] (where L = pqCH₃2 and pqCl 3) were synthesized, characterized, studied and compared to Re(CO)₃Clpq, 1. Complex 2 crystallizes in space group C2/c with a = 20.4476(17) Å, b = 15.4521(13) Å, c = 15.2887(13) Å, β = 126.1210(11)°, Z = 8 and V = 3902.0(6) Å³. The substitution of -H by -CH₃ or -Cl at 6-position of pq has a minor electronic effect on the pyridyl ring of the ligands, but seems to influence the quinoxaline moiety enough to alter the spectroscopical and electrochemical features.     

Ferrocene-decorated (phthalocyaninato)(porphyrinato) double- and triple-decker rare earth complexes: synthesis, structure, and electrochemical properties

A series of four mixed (phthalocyaninato)(porphyrinato) rare earth double-decker complexes (Pc)M[Por(Fc)(2)] [Pc = phthalocyaninate; Por(Fc)(2) = 5,15-di(ferrocenyl)-porphyrinate; M = Eu (1), Y (2), Ho (3), Lu (4)] and their europium(III) triple-decker counterpart (Pc)Eu(Pc)Eu[Por(Fc)(2)] (5), each with two ferrocenyl units at the meso-positions of their porphyrin ligands, have been designed and prepared. The double- and triple-decker complexes 1-5 were characterized by elemental analysis and various spectroscopic methods. The molecular structures of two double-deckers 1 and 4 were also determined by single-crystal X-ray diffraction analysis. Electrochemical studies of these novel sandwich complexes revealed two consecutive ferrocene-based one-electron oxidation waves, suggesting the effective electronic coupling between the two ferrocenyl units. Nevertheless, the separation between the two consecutive ferrocene-based oxidation waves increases from 1 to 4, along with the decrease of rare earth ionic radius, indicating the effect of rare earth size on tuning the coupling between the two ferrocenyl units. Furthermore, the splitting between the two ferrocene-based one-electron oxidations for triple-decker 5 is even smaller than that for 1, showing that the electronic interaction between the two ferrocene centers can also be tuned through changing the linking sandwich framework from double-decker to triple-decker. For further understanding of the electronic coupling between ferrocenyl groups, DFT calculation is carried out to clarify the electronic delocalization and the molecular orbital distribution in these double-decker complexes.     

Chloride-bridged oxovanadium(V) complexes with alkoxyalkoxide ligands. Synthesis, structure, electrochemistry and reactivities

A series of mixed alkoxyalkoxo chloro complexes of vanadium(V), [VOCl2(OCH2CH2OR)]2 (R = Me, Et, iPr, Bz), [VOCl2(OCMe2CH2OMe)]2 and [VOCl2(OCH2(cyclo-C4H7O)]2, were synthesised and characterised. The title compounds can be obtained either from VOCl3 and the alkoxyalcohols by HCl elimination or from the corresponding lithium alkoxides and VOCl3 by salt metathesis reaction. X-Ray diffraction studies revealed the title compounds to be dimers with chloride bridging ligands and intramolecular ether coordination. Electrochemical results obtained by cyclic voltammetry indicate irreversible, reductive behaviour. The interactions of the title compounds with oxygen, nitrogen and phosphorus donor ligands were examined. Phosphorus and nitrogen donors lead to reduction products whereas tetrahydrofuran coordinates to the vanadium(V) centre by breaking the chloride bridge. All tetrahydrofuran complexes, [VOCl2(OCH2CH2OR)(thf)] (R = Me, Et, iPr) and [VOCl2(OCMe2CH2OMe)(thf)], have been characterised by single-crystal X-ray diffraction. The solid-state structures of these complexes show that they consist of six-coordinate monomers. Reaction of [VOCl2(OCH2CH(2)OMe)]2 with Me3SiCH2MgCl gave [VO(CH2SiMe3)3], which has been structurally characterised. The compounds were tested as catalysts for epoxidation and polymerisation reactions. They convert unfunctionalised olefins into the corresponding epoxides with moderate activity. They are good pre-catalysts for the polymerisation of ethene and oligomerise 1-hexene.     

Synthesis, structure, and spectroscopic and magnetic properties of mesomorphic octakis(hexylthio)-substituted phthalocyanine rare-earth metal sandwich complexes

The syntheses of new bis[octakis(hexylthio)phthalocyaninato] rare-earth metal(III) double-decker complexes [(C6S)8-Pc]2M (M = Gd(III), Dy(III), and Sm(III)) (2-4, respectively) are described. These compounds are very soluble in most common organic solvents. They have been fully characterized using elemental analysis, infrared, UV-vis spectroscopy, and mass spectrometry. The crystal structures of compounds 2-4 have been determined by X-ray diffraction on a single crystal. They are isostructural and crystallize in the monoclinic space group (space group C2/c). Their lattice constants have been determined in the following order: (2) a = 31.629(4) Angstroms, b = 32.861(4) Angstroms, c = 20.482(2) Angstroms, beta = 126.922(2) degrees, V = 17019(3) Angstroms(3); (3) a = 31.595(2) Angstroms, b = 32.816(2) Angstroms, c = 20.481(1) Angstroms, beta = 127.005(1) degrees, V = 16958(2) Angstroms(3); (4) a = 31.563(2) Angstroms, b = 32.796(2) Angstroms, c = 20.481(1) Angstroms, beta = 127.032 degrees, V = 16924(2) Angstroms(3). The magnetic properties of compounds 2-4 were studied, and it was revealed that the lanthanide ions and the radical delocalized on the two phthalocyanine rings are weakly interacting. The mesogenic properties of these new materials were studied by differential scanning calorimetry and optical microscopy. These phthalocyanine derivatives form columnar-hexagonal (Col(h)) mesophases. Thin films of bis[octakis(hexylthio)phthalocyaninato] rare-earth metal(III) double-decker complexes (2-4) were prepared by a spin-coating technique. Thermally induced molecular reorganization within films of bis[octakis(hexylthio)phthalocyaninato] rare-earth metal(III) double-decker complexes (2-4) was studied by the methods of ellipsometry, UV-vis absorption spectroscopy, and atomic force microscopy. Heat treatment produces molecular ordering, which is believed to be due to stacking interaction between neighboring phthalocyanine moieties.     

Synthesis,molecular geometry,spectroscopic studies and thermal properties of Co(II) complexes

Co(II) complexes (1‐4) were prepared and characterized by elemental analyses, infrared spectra, spectral studies, magnetic susceptibility measurements, X‐ray diffraction analysis and thermogravimetric analysis (TGA). The X‐ray diffraction patterns of Co(II) complexes were observed many peaks which indicate the polycrystalline nature. The thermodynamic parameters were calculated by using Coats–Redfern and Horowitz–Metzger methods. The bond length, bond angle and quantum chemical parameters of the Co(II) complexes were studied and discussed. The Co(II) complexes were tested against various Gram‐positive bacteria, Gram‐negative bacteria and fungi. It was found that the Co(II) complex (1) has more antifungal activity than miconazole (antifungal standard drug) against P. italicum at all concentration. The Co(II) complex ( 2 ) has more antibacterial activity than the penicillin against K. pneumoniae at all concentration. The interaction between Co(II) complexes and calf thymus DNA show hypochromism effect. The relationship between the values of HOMO–LUMO energy gap (?E) and the values of intrinsic binding constant (K_b) is revealed increasing of HOMO–LUMO energy gap accompanied by the decrease of K_b.     

Synthesis, structures and spectroscopic properties of cyclometalated tri-tert-butylphosphine complexes of platinum(II)

Reactions of [Pt₂(μ-Cl)₂(C^∩P)₂] (C^∩P = CH₂C(Me₂)PBu^t₂-C,P) with various anionic ligands differing in ligand bite and denticity have been investigated and the resulting products have been characterized by elemental analyses and NMR (¹H, ¹³C, ³¹P, ¹⁹⁵Pt) spectroscopy. Stereochemistry of the complexes has been deduced by NMR spectroscopy. Structures of [Pt₂(μ-SPh)₂(C^∩P)₂], [Pt₂(μ-pz)₂(C^∩P)₂], [PtCl(Spy)(PBu^t₃)], [Pt₂(μ-SCOPh)₂(C^∩P)₂] and [Pt{S₂P(OPrⁱ)₂}(C^∩P)] have been established by single crystal X-ray diffraction analyses. The complex [Pt₂(μ-SPh)₂(C^∩P)₂] adopts a sym cis configuration while other binuclear complexes exist in a sym trans configuration. The molecular structure of [Pt{S₂P(OPrⁱ)₂}(C^∩P)] revealed that complex comprises of two four-membered chelate rings but in solution a dimeric structure based on ¹⁹⁵Pt NMR data has been suggested.     

Synthesis, structure and properties of molybdenum(0) bialkyne complexes

The reaction of Mo(NN)(CO)₄ (NN = bipyridine, phenathroline) with CH₃OOCCCCOOCH₃ (DMAC) gives Mo(NN)(CO)₄(DMAC)₂. An X-ray diffraction study of the product (NN = bipyridine) indicates that the two CO groups are cis to each other, while the two DMAC ligands are in trans arrangement, and are mutually perpendicular with each DMAC eclipsing and N---Mo---CO vector. In solution, the DMAC ligands appear to rotate about the Mo---DMAC bond as shown by the fluxional behavior in the NMR spectra of the products.