The RuCl3(dppb)H2O complex: A new metal-assisted oxidative dehydrogenation of the o-phenylenediamine ligand

The trans-[RuCl₂(dppb)(bqdi)] and trans-[RuCl₂(dppb)(opda)] complexes (dppb = 1,4-bis(diphenylphosphine)butane, bqdi = o-benzoquinonediimine, and opda = o-phenylenediamine) were synthesized from the reaction of the mer-[RuCl₃(dppb)(H₂O)] aqua-complex with the opda ligand. The X-ray structural and electrochemical characterizations of the isolated compounds showed that this aqua-complex induces the oxidative dehydrogenation of the amine species (opda) to the imine form (bqdi) of the o-phenylene ligand during the synthetic procedure. In the presence of oxygen, the ³¹P{¹H} NMR experiments confirmed that the trans-[RuCl₂(dppb)(bqdi)] complex is the only product formed.     

Synthesis,Characterization, and Reactivity of trans-Ru(X)(Cl)(nbd)(dppb) (X = H,Cl; nbd = 2,5-norbornadiene; dppb = 1,4-bis(diphenylphosphino)butane), Including the X-ray Crystal Structure of the Dichloride

The ruthenium (II) diene complexes [Ru(X)(Cl)(nbd)(dppb)] (X = Cl, H; nbd = 2,5-norbornadiene; dppb = PPh₂(CH₂)₄PPh₂) have been prepared and characterized spectroscopically. The X-ray crystal structure of RuCl₂(nbd)(dppb) (crystal data at 22°C: space group P1, a = 10.896 (1) Å, b = 15.168(2) Å, c = 10.829 (1) Å, α = 103.02(1)°, β = 107.08(1)°, γ = 81.65(1)°, Z = 2, R = 0.054 for 6420 reflections) shows an octahedral geometry at Ru, with the chloro ligands slightly distorted from a trans configuration (Cl)(1)-Ru-C1(2) = 168.4°); the unit cell contains two molecules of the complex and one molecule of benzene. Reaction of this complex with H₂, in presence of Proton Sponge (PS, 1,8-bis(dimethylamino)naphthalene) as base, is complicated by initial dissociation of nbd, and [Ru₂Cl₅(dppb)₂]⁻-PSH⁺ is the major product. A minor product, the hydrido(diene) complex trans-RuCl(nbd)(dppb) 5 , characterized spectroscopically, is more effectively synthesized from (a) trans-Ru(H)Cl(nbd)(PPh₃)₂, 1 , and dppb, or (b) reaction of RuCl₂(dppb)-(PPh₃) with H₂ in presence of nbd and PS. Complex 5 is unreactive toward H₂ or CO while 1 has been shown previously to give η²-H₂ and norbornenoyl derivatives, respectively; the differences in reactivity are discussed.     

Silver(I)-mediated isomerisation of trans-[RuCl2(P-P)2] (P-P=4-membered ring chelate diphosphine ligand) and its application in the syntheses of [RuCl(L)(P-P)2]+ (L=neutral ligand)

Conversion of trans-[RuCl₂(P-P)₂] (P-P=4-membered chelate diphosphine) to cis is facilitated by treatment with AgOTf or AgBF₄ in 1,2-dichloroethane, which gives mixtures of Ru–Cl–Ag heterobimetallic complexes with cis stereochemistry at Ru(II), characterised by ³¹P{¹H} and ¹H NMR spectroscopy and by FAB mass spectrometry. Treatment of these mixtures with neutral ligands (CO, CH₃CN) gives cis-[RuCl(L)(P-P)₂]⁺, whereas simultaneous treatment of trans-[RuCl₂(P-P)₂] with L and Ag(I) salt gives trans-[RuCl(L)(P-P)₂]⁺.     

Synthesis and X-ray crystal structure determination of monomeric cis-Pd(2,2′-bipyridine)(NO3)2

Complex cis-Pd(2,2′-bipyridine)(NO₃)₂ was synthesized by the reaction of cis-Pd(2,2′-bipyridine)Cl₂ with AgNO₃ in water and crystallized by vapor diffusion of diethyl ether into an acetonitrile solution of the complex. The crystal structure obtained shows that each of the two nitrate ligands are coordinated through oxygen atoms to the Pd(2,2′-bipyridine)²⁺ center in unidentate fashion. IR and ¹H NMR spectral data were also obtained.     

Molecular structures and vibrational frequencies for cis-[PdCl2(tmen)] and cis-[Pd(N3)2(tmen)]: A DFT study

Theoretical molecular structures of the complexes cis-[PdCl₂(tmen)] and cis-[Pd(N₃)₂(tmen)] (tmen = N,N,N′,N′-tetramethylethylenediamine) were investigated using B3LYP/DFT method. The calculated molecular parameters, bond distances and angles, revealed a square-planar geometry around the metallic center for both compounds with the azide being linear. The theoretical infrared spectra of C₁ symmetry (electronic state ¹A) of the compounds are in agreement with the experimental data.     

A novel infinite 1D covalent chain of end-to-end thiocyanato bridged heptacoordinated cadmium(II)Schiff base: π…π interaction and weak C–H…S hydrogen bonded supramolecule

A new Schiff base, N,N′-(bis(pyridin-2-yl)formylidene)ethane-1,2-diamine (bpfd) is prepared and used to synthesize a novel end-to-end thiocyanato bridged infinite 1D polymeric heptacoordinated cadmium(II) chain [Cd(bpfd)(μ_1,3-NCS)(NCS)]_n (1) which forms a 3D supramolecule through weak C–H…S hydrogen bonding and π…π interaction.     

Ditopic, flexible hydrazone-based building blocks with pendant 2,2′:6′,2′′-terpyridine metal-binding domains

The synthesis and characterization of three new bis(2,2′:6′,2′-terpyridine) (tpy) ligands containing different hydrazone spacers between the metal-binding domains are described. Treatment of 1,4-benzenedicarbaldehyde bis(2,2′:6′,2′′-terpyridin-4′-ylhydrazone) (1) with [(tpy)RuCl₃] in the presence of N-ethylmorpholine results in the formation of [(tpy)Ru(μ-1)Ru(tpy)]⁴⁺. Single crystal X-ray diffraction data for [(tpy)Ru(μ-1)Ru(tpy)][PF₆]₄·8MeCN confirm the ability of the hydrazone-based ligand to bridge two ruthenium(II) centres, providing proof-of-principle for the application of this class of flexible ligand in the design of coordination polymers.     

Anion-directed assembly of two novel cadmium(II) complexes constructed by 2,2′-(1,4-butanediyl)bis(1H-benzimidazole) ligand

Depending on the different coordinated anions used, reaction of Cd(II) salt with 2,2′-(1,4-butanediyl)bis(1H-benzimidazole) results in the formation of two coordination polymers: a 1D chain {[Cd(H₂C4BIm)Cl₂] · (H₂C4BIm)}_n (1), and a 2D sheet [Cd(HC4BIm)(NCS)]_n (2) which features distorted 4.8² topology (H₂C4BIm = 2,2′-(1,4-butanediyl)bis(1H-benzimidazole)). The fluorescence properties for both the complexes have been studied.     

Preparation, characterization and taste sensing properties of Langmuir-Blodgett Films from mixtures of polyaniline and a ruthenium complex

Langmuir-Blodgett (LB) films from a ruthenium complex, mer-[RuCl₃(dppb)(py)] (dppb=PPh₂(CH₂)₄PPh₂; py=pyridine) (Rupy), and from mixtures with varied amounts of polyaniline (PANi) were fabricated. Molecular-level interactions between the two components are investigated by surface potential, dc conductivity and Raman spectroscopy measurements, particularly for the mixed film with 10% of Rupy. For the latter, the better miscibility led to an interaction with Rupy inducing a decrease in the conducting state of PANi, as observed in the Raman spectra and conductivity measurement. The interaction causes the final film properties to depend on the concentration of Rupy, and this was exploited to produce a sensor array made up of sensing units consisting of 11-layer LB films from pure PANi, pure Rupy and mixtures with 10 and 30% of Rupy. It is shown that the combination of only four non-specific sensing units allows one to distinguish the basic tastes detected by biological systems, viz. saltiness, sweetness, sourness and bitterness, at the μM level.     

Ruthenium(III) Complexes of Heterocyclic Tridentate (ONN) Schiff Base: Synthesis,Characterization and its Biological Properties as an Antiradical and Antiproliferative Agent

The current work reports the synthesis, spectroscopic studies, antiradical and antiproliferative properties of four ruthenium(III) complexes of heterocyclic tridentate Schiff base bearing a simple 2′,4′-dihydroxyacetophenone functionality and ethylenediamine as the bridging ligand with RCHO moiety. The reaction of the tridentate ligands with RuCl₃·3H₂O lead to the formation of neutral complexes of the type [Ru(L)Cl₂(H₂O)] (where L = tridentate NNO ligands). The compounds were characterized by elemental analysis, UV-vis, conductivity measurements, FTIR spectroscopy and confirmed the proposed octahedral geometry around the Ru ion. The Ru(III) compounds showed antiradical potentials against 2,2-Diphenyl-1-Picrylhydrazyl (DPPH) and 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radicals, with DPPH scavenging capability in the order: [(PAEBOD)RuCl₂] > [(BZEBOD)RuCl₂] > [(MOABOD)RuCl₂] > [Vit. C] > [rutin] > [(METBOD)RuCl₂], and ABTS radical in the order: [(PAEBOD)RuCl₂] < [(MOABOD)RuCl₂] < [(BZEBOD)RuCl₂] < [(METBOD)RuCl₂]. Furthermore, in vitro anti-proliferative activity was investigated against three human cancer cell lines: renal cancer cell (TK-10), melanoma cancer cell (UACC-62) and breast cancer cell (MCF-7) by SRB assay.     

The formation of [RuCl(p-cymene)(Me2HPz)(PPh2OR)]Cl (Me2HPz=3, 5-dimethylpyrazole; R=H,Me and p-Tol) complexes from the cleavage of the P–N bond of a P-coordinated P(Me2Pz)Ph2 ligand by ROH molecules in a ruthenium(II) complex. Crystal structure of [RuCl(p-cymene)(Me2HPz)(PPh2OH)]Cl

The complex [RuCl₂(p-cymene)]₂ reacts with 1-(3,5-dimethyl)pyrazolyldiphenylphosphine (P(Me₂Pz)Ph₂) to give the complex RuCl₂(p-cymene)(P(Me₂Pz)Ph₂). This compound reacts with ROH molecules (R=H, Me and p-Tol) to give [RuCl(p-cymene)(Me₂HPz)(PPh₂OR)]Cl (R=H, Me and p-Tol) complexes, which contain both Me₂HPz and PPh₂OR coordinated molecules.     

Unique direct synthesis of cyanide-bridged Fe2Cu2 molecular squares by destruction of sodium nitroprusside

The one-pot reaction of copper powder, sodium nitroprusside, ammonium thiocyanate and 2,2′-bipyridine (bpy) in acetonitrile solution at ambient conditions of air and water yields the novel heterometallic [Fe₂Cu₂(bpy)₆(μ-CN)₄(NCS)₂]₂[Fe(CN)₅(NO)](NCS)₂·5H₂O complex 1, which has been structurally and magnetically characterized. The most prominent feature of this complex is the unique tetranuclear squares comprised [Cu(bpy)NCS]⁺ and [Fe(bpy)₂]²⁺ corners with CN edges. The CuCu and FeFe separations are 6.72 and 7.73 Å, respectively. The variable-temperature magnetic susceptibility study revealed that a very weak antiferromagnetic coupling is active between Cu(II) centers (J_CuCu = −0.37 cm⁻¹).     

Polyimides from a Novel Monomer 3,6-Bis(dimethylamino)acridine(p-cymene)dichlororuthenium(II) for a Catalytic Application

Tricyclic heteroaraomatic dye-based monomer containing NMe₂ units, 6-bis(dimethylamino)acridine(p-cymene)dichlororuthenium (II), was used to prepare novel polyimides via a one-stage solution polycondensation due to their stability under a variety of oxidative and reductive conditions. The Ru(II) complex monomer was synthesized starting from [RuCl₂(p-cymene)]₂ and 3,6-bis(dimethylamino)acridine. A series of stable polyimides was synthesized from the Ru(II) complex of 3,6-bis(dimethylamino)acridine and various aromatic dianhyrides. The polymers had inherent viscosities ranging from 1.72 to 2.11 dL/g and were soluble in polar solvents. The glass transition temperatures were 192–278 °C, and the 10% weight loss temperatures were above 503–635 °C. Ruthenium-substituted polyimides were tested for catalytic activity in the furan formation reaction of (Z)-3-methylpent-2-en-4-yn-1-ol. The polymeric catalyst was added to (Z)-3-methylpent-2-en-4-yn-l-ol without a solvent and the pure furan was isolated by distillation under reduced pressure. The conversion of the starting, enynol, was determined by gas chromatography (GC).     

DNA binding of mixed-metal supramolecular Ru, Pt complexes

The mixed-metal supramolecular complexes [(tpy)Ru(PEt₂Ph)(dpp)PtCl₂](PF₆)₂ and [(tpy)Ru(PEt₂Ph)(bpm)PtCl₂](PF₆)₂ are of interest in that they couple light absorbing ruthenium centers to a reactive metal site through a communicative bridge (tpy=2,2^′:6^′,2^′′-terpyridine, BPM=2,2^′-bipyrimidine and DPP=2,3-bis(2-pyridyl)pyrazine). These systems have been studied and shown to avidly bind to DNA, greatly reducing its mobility through an agarose gel.     

Coordinate chloride and water-assisted assembly of novel 3D-cageworks of cadmium(II) complex with 4-[N,N-bis(2-cyanoethyl)]aminopyridine

Synthesis and structure of the cadmium(II) complex of [Cd^II(CEAP)₂(H₂O)(CH₃COO)Cl] {CEAP = 4-[N,N-bis(2-cyanoethyl)]aminopyridine} has been reported. The structure exhibits a novel 3D-cagework assembly with the assistance of the coordinated chloride anion and water molecule via forming multiple hydrogen bonds with the cyanoethyl arms of CEAP.     

Synthesis of New Polyimides from Ru (II) Complex of 2,6-bis [1-(p-dimethylaminophenylimino) Ethyl] Pyridine

Pyridine-based tridentate ligand containing pendant NMe₂ unit was used to prepare novel polyimides via one-stage solution polycondensation due to their stability under a variety of oxidative and reductive conditions. Ru (II) complex of the pydim ligand was synthesized starting from [RuCl₂ (p-cymene)]₂ and 2,6-bis [1-(p-dimethylaminophenylimino) ethyl] pyridine. A series of stable polyimides were synthesized from Ru (II) complex of 2,6-bis [1-(p-dimethylaminophenylimino) ethyl] pyridine (2) and various aromatic dianhyrides had inherent viscosities ranging from 1.31 to 1.55 dL/g and were soluble in polar solvents. The glass transition temperatures were 245–308°C, and the 10% weight loss temperatures were above 482–548°C.     

Synthesis of a novel μ-acetate bridged dinuclear Cu(II) complex as model compound for the active site of tyrosinase: crystal structure, magnetic properties and catecholase activity

Reaction of the ligand N,N,N^′,N^′-bis[(2-hydroxybenzyl)(N-methylimidazolyl)]-2-ol-1,3-propendiamine (Hbhbmipo) with copper(II) perchlorate and sodium acetate in acetonitrile/ethanol leads to the assembly of a novel dinuclear copper(II) complex. The crystal structure, magnetic properties and its catecholase activity are reported. Both copper(II) ions are set in a distorted square pyramidal coordination sphere with a N₂O₃ donor set resulting in a CuCu distance of 3.382(5) Å. To our knowledge this is the first example of a dinuclear Cu(II) complex with square pyramidal coordination geometry in which the N₂O₃ donor set contains N-imidazol and O-phenol. The complex represents a structural model for a tyrosine intermediate in the proposed mechanism during hydroxylation of monophenols.     

Syntheses,characterisation and ligand substitution reactions of the useful synthons [Ru(OTf)2(P-P)2] (P-P=4-membered ring chelate diphosphine ligand)

Treatment of trans-[RuCl₂(P-P)₂] (P-P=4-membered chelate diphosphine) with 2 equiv. of AgOTf in 1,2-dichloroethane gave labile complexes formulated cis-[Ru(OTf)₂(P-P)₂], which readily undergo ligand substitution reactions with neutral or anionic ligands to give cis-[Ru(L)₂(P-P)₂]²⁺ or [RuX₂(P-P)₂]; these have been characterised by ³¹P{¹H} and ¹H NMR spectroscopy, FAB mass spectrometry and (in some cases) X-ray crystallography.     

Synthesis, photoluminescence, and theoretical studies of novel Cu(I) complex

A novel diimine Cu(I) complex [Cu(ABPQ)(DPEphos)]BF₄ [ABPQ and DPEphos are acenaphtho[1,2-b]bipyrido[2,3-h;3,2-f]quinoxaline and bis(2-(diphenylphosphanyl)phenyl) ether, respectively] is synthesized, and its photophysical properties are experimentally and theoretically characterized. The emission bands centered at ca. 400/470 and 550 nm of [Cu(ABPQ)(DPEphos)]BF₄ are attributed to the ligand-centered π → π* transition and the metal-to-ligand charge transfer dπ(Cu) → π*(N–N) transition, respectively. The luminescence quantum yield of [Cu(ABPQ)(DPEphos)]BF₄ in CHCl₃ is found to be about five times higher than that of [Cu(Phen)(DPEphos)]BF₄.     

Synthesis,characterization, electropolymerization,and possible utilities of a new ruthenium–thiophene complex

[RuCl₂(p‐cymene)]₂ was reacted with silver triflate and thiophene to give the sandwich complex [Ru(η⁵‐C₄H₄S)(η⁶‐p‐cymene)](PF₆)₂, which was characterized with NMR spectroscopy (¹H‐NMR, ¹³C‐NMR, and ³¹P‐NMR), Fourier transform infrared spectroscopy, elemental analysis, and cyclic voltammetry. The behavior of this new complex in dimethyl sulfoxide with regard to the amount of absorbed water was investigated by both NMR and cyclic voltammetry; the formation of other species that affected electropolymerization was demonstrated. However, under optimal working conditions (in an anhydrous medium), the complex was successfully immobilized on a platinum electrode via an electro‐oxidation pathway through the thiophene ligand. This generated a highly stable, electroactive polymer film. Its response to the doping–undoping (charge–discharge) and redox processes, added to its high stability, promises important applications for this novel material. Moreover, this opens up the possibility of testing other compounds, such as [Ru(η⁵‐thiophene)(η⁶‐arene)], that were previously synthesized and reported for their electropolymerization and use as sensors according to their redox properties. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43559.