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 and characterization of trans-[Ru(NO)Cl(L)4](PF6)2 (L = isonicotinamide; 4-acetylpyridine) and related species

The trans-[RuCl₂(L)₄], trans-[Ru(NO)Cl (L)₄](PF₆)₂ (L = isonicotinamide and 4-acetylpyridine) and trans-[Ru(NO)(OH)(py)₄]Cl₂ (py = pyridine) complexes have been prepared and characterized by elemental analysis, UV–visible, infrared, and ¹H NMR spectroscopies, and cyclic voltammetry. The MLCT band energies of trans-[RuCl₂(L)₄] increase in the order 4-acpy < isn < py. The reduction potentials of trans-[RuCl₂(L)₄] and trans-[Ru(NO)Cl(L)₄]²⁺ increase in the order py < isn < 4-acpy. The stretching band frequency, ν_NO, of the nitrosyl complexes ranges from 1913 to 1852 cm^?1 indicating a nitrosonium character for the NO ligand. Due to the large π-acceptor ability of the equatorial ligands, the coordinated water is much more acidic in the water soluble trans-[Ru(NO)(H₂O)(py)₄]³⁺ than in trans-[Ru(NO)(H₂O)(NH₃)₄]³⁺.     

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.     

Ligand dehydrogenation in ruthenium trinitrogen complexes: synthesis,structure and chirality of the cations [Ru(LH4)(L)]2+ [LH4=2,6-bis(pyrrolidin-2-yl)pyridine]

Reaction of 2,6-bis(pyrrolidin-2-yl)pyridine (LH₄) with RuCl₃·3H₂O in refluxing methanol/water mixtures gives rise to the formation of the octahedral complexes [Ru(LH₄)(L)]²⁺, in which one of the two trihapto ligands has been dehydrogenated as 2,6-bis(3,4-dihydro-2H-pyrrol-5-yl)pyridine (L), even if LH₄ was present in excess. With the three stereoisomers of LH₄, the complexes [Ru(R,S-LH₄)(L)]²⁺ (meso), [Ru(R,R-LH₄)(L)]²⁺ and [Ru(S,S-LH₄)(L)]²⁺ have been isolated as the perchlorate salts and characterised by X-ray structure analysis and by CD spectra.     

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 crystal structure of a novel thiocyanate–ruthenium(II) complex

The cis-[Ru(dppb)(Me-bipy)(NCS)₂], dppb = 1,4-bis (diphenylphosphino)butane, Me-bipy = 4,4′-dimethyl-2,2′-bipyridine, and NCS = thiocyanate, was synthesized and characterized by spectroscopic and electrochemical techniques and its structure was determined by crystal X-ray analysis. The crystal structure reveals that the coordination geometry around the Ru(II) center is distorted octahedron where two molecules of thiocyanate are bonded to the ruthenium through nitrogen atom in cis orientation. The half-wave formal potential value E_1/2 = 0.8 V (versus Ag/AgCl) observed is considerable higher than that for the cis-[RuCl₂(dppb)(Me-bipy)] complex, E_1/2 = 0.6 V (versus Ag/AgCl), well illustrating the strong π-acceptor effect the NCS ligand toward the backbonding interaction with the Ru(II) metal center. The MLCT absorption bands of the thiocyanate complex present a higher molar absorptivity (about 12%) compared with the cis-[RuCl₂(dppb)(Me-bipy)] complex, in the same experimental conditions. These properties make the complex potentially promising for the photosensitization process.     

Oxotungsten(VI) complexes with amino(phenolate)alcoholate ligand

The reaction between tungsten(VI) complex [W(eg)₃] (eg = 1,2-ethanediolato dianion) and a phenolic ligand precursor 2,4-di-tert-butyl-6-(((2-hydroxyethyl)(methyl)amino)methyl)phenol (H₂L) affords a monomeric oxotungsten complex [WO(eg)(L)]. This complex reacts further with Me₃SiCl, which leads to the displacement of ethanediolato ligand from the complex unit and formation of cis- and trans-isomers of corresponding dichloro complex [WOCl₂(L)]. Identical dichloro complexes were also prepared by the reaction between H₂L and WOCl₄. Molecular structure of [WO(eg)(L)] was verified by X-ray crystallography.     

Isomerism in bis(phenylselenolato)bis(triphenylphosphine)platinum(II): the crystal and molecular structures of cis- and trans-[Pt(SePh)2(PPh3)2]

The reaction of cis-[PtCl₂(PPh₃)₂] and NaSePh in benzene produces a mixture of cis- and trans-isomers of the monomeric platinum complex [Pt(SePh)₂(PPh₃)₂]. The low-temperature X-ray structures of both isomers are reported. The structure of cis-[Pt(SePh)₂(PPh₃)₂] is the first crystallographic characterized cis-isomer of mononuclear platinum(II) complex containing only non-chelating organoselenolato and phosphine ligands.     

Synthesis and structural characterization of [RuCl2(CO)2(TePh2)2]·1/2C6H6

The reaction of Ph₂Te with [RuCl₂(CO)₃]₂ affords a monomeric ruthenium complex [RuCl₂(CO)₂(TePh₂)₂]. The X-ray structure shows the formation of the trans(Ph₂Te), cis(Cl), cis(CO) isomer. The ¹³C NMR and ¹²⁵Te NMR spectra of the complex are reported.     

The trigonal-bipyramidal [ReOI2(PPh3)2] — The first monomeric oxorhenium(IV) complex with monodentate ligands only

The reaction of cis-[Re^VO₂I(PPh₃)₂] with 2-(3,5-dimethylpyrazol-1-yl)benzothiazole (dbt) in ethanol led to the isolation of the trigonal-bipyramidal oxorhenium(IV) complex trans-[ReOI₂(PPh₃)₂] (1). The complex is the first example of a monomeric oxo complex of rhenium(IV). Complex 1 was characterized by FTIR, ¹H NMR, microanalysis and single crystal X-ray diffraction.     

Oxidation of Pt(II) to Pt(IV) complex with hydrogen peroxide in glycols

The reaction of cis, cis-[Pt^II(9-fm)(dmpda)] (9-fm=9-fluorenylidenemalonate, dmpda=2,2-dimethyl-1,3-propanediamine) with hydrogen peroxide in ethyleneglycol produces cis,trans,cis-[Pt^IV(9-fm)(OCH₂CH₂OH)(OH)(dmpda)]. Its crystal structure shows that the local geometry around the platinum atom approximates a typical octahedral arrangement with the added OCH₂CH₂OH/OH ligands in trans coordination sites. The molecules are packed in a two-dimensional assembly via van der Waals interactions, where the hydrophobic fluorenyl groups are arranged on both faces of the assembly plate whereas the hydrophilic groups fill up the inner part of the plate. The compound bearing both “inorganic OH” and “organic OH” is a potential precursor for further various functionalizations.     

Six isostructural lanthanide-containing MOFs built on a semi-rigid tripodal organic ligand

By using a semi-rigid tripodal ligand 1,1′,1′′-(2,4,6-trimethylbenzene-1,3,5-triyl)tris(methylene)tripyridinium-4-olate) (L), six isomorphous lanthanum metal-organic frameworks (MOFs), namely, [Pr(L)₂(Cl)₂]·(Cl)(DMF)_0.5·(H₂O)·(1), [Nd(L)₂(Cl)₂]·(Cl)(2), [Tb(L)₂(Cl)₂]·(Cl)·(DMF)·(H₂O)(3), [Eu(L)₂(Cl)₂]·(Cl)(DMF)·(H₂O)(4), [La(L)₂(Cl)₂]·(Cl)(5), [Sm(L)₂(Cl)₂]·(Cl) (DMF)·(H₂O) (6), were obtained and characterized by single crystal X-ray diffraction, IR and elemental analysis. Six compounds are isostructural with Ln^3 + (Ln = Pr, Nd, Tb, Eu, La, Sm) and in which the Ln^3 + is considered as a 6-connecting node and the L ligand is a 3-connecting node to afford a (3,6)-connected 2D layer with kgd topology, which further stacks into 3D supramolecular networks through C-H^…O weak interactions. Luminescent properties of these lanthanide MOFs have also been assessed at ambient temperature, in which the Pr^3 +-1 and the La^3 +-5 are slightly blue-shifted with respect to the ligand. Series of sharp peaks characteristic of the Eu^3 +-4, the Tb^3 +-3 and Sm^3 + − 6 metal-centered luminescence appear. The Nd^3 +-2 has no emission.     

Stereoselective ion association of [Co(en)2(phen)]3+ with metal complex anions

Ion association constants of Λ- and Δ-[Co(en)₂(phen)]³⁺ (en=ethylenediamine and phen=1,10-phenanthroline) with Δ-[Co(mal)₂(gly)]²⁻ (mal=malonate and gly=glycinate), Δ-[Co(ox)₂(gly)]²⁻ (ox=oxalate), and Δ-C₁-cis(N)-[Co(ox)(gly)₂]⁻ in aqueous solution were determined at 25°C and an ionic strength of 0.01 M by the conductivity method. The preferred ion pair between [Co(en)₂(phen)]³⁺ and the above three complex anions was ΔΔ (homochiral combination), contrasting with a heterochiral (ΛΔ) preference for the ion pair between [Co(en)₃]³⁺ and the same complex anions. In addition, the discrimination factors, K(ΔΔ)/K(ΛΔ), in the [Co(en)₂(phen)]³⁺ systems were appreciably larger than those in the corresponding [Co(en)₃]³⁺ systems. The results are interpreted in terms of the interaction mode different from that of [Co(en)₃]³⁺, and the ion association model responsible for the chiral recognition by [Co(en)₂(phen)]³⁺ is proposed.     

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.     

Synthesis,molecular, crystal and electronic structure of [RuCl2(PPh3)2(C3N2H4)2]

The reaction of [RuCl₂(PPh₃)₃] complex with pyrazole has been examined. A new ruthenium complex – [RuCl₂(PPh₃)₂(C₃N₂H₄)₂] has been obtained and characterised by IR and UV–Vis measurements. Crystal and molecular structure of the complex has been determined.     

Stabilisation of Au and Au in the same complex molecule by a tridentate phosphinodithiolate ligand. Structures of [AuLCl] and [AuL2Au] (L = {PhP(C6H3S-2-SiMe3-3)2})

The reaction of the organometallic complex [Au^III(damp-C^I,N)Cl₂] (damp-C,N⁻ = dimethylaminomethylphenyl) with PhP(C₆H₃SH-2-SiMe₃-3) ₂, H₂L, results in cleavage of the AuC bond and the formation of [Au^IIILCl] and [Au^IL₂Au^III] complexes. The square coordination environment of gold in [AuLCl] is noticeably distorted (maximum deviation from planarity: 0.326(1) Å) by the steric requirements of the tridentate chelating ligand, but the oxidation state ‘+3’ of the metal is retained. [Au^IL₂Au^III] contains gold atoms in both square-planar (Au^III) and linear (Au^I) coordination environments. The square-planar Au^III is bound by two trans-chelated PS units, and the two remaining thiolate groups provide the linear coordination of Au^I. The Au-Au distance is 2.919(1) Å, indicative of a weak bonding interaction.     

Coexistence of two distinct axial ligands and their thermo-induced substitution in trans-[FeL2(NCS)2][FeL2(CH3OH)2](NCS)2 (L = 4-amino-3-(p-chlorophenyl)-5-(2-pyridyl)-1,2,4-triazole)

A novel iron(II) complex, trans-[FeL₂(NCS)₂][FeL₂(CH₃OH)₂](NCS)₂ (1) with 4-amino-3-(p-chlorophenyl)-5-(2-pyridyl)-1,2,4-triazole (L) has been successfully synthesized and characterized. X-ray crystallography analysis shows that 1 is the first example in the mononuclear triazole-based complexes consisting of two distinct molecules: trans-[FeL₂(NCS)₂] and trans-[FeL₂(CH₃OH)₂](NCS)₂ with each octahedral iron(II) center coordinated axial by two NCS⁻ ions in Fe1 but two MeOH molecules in Fe2. Moreover, 1 can lose two MeOH molecules at 220 °C to form trans-[FeL₂(NCS)₂] (2) which can be transformed to 1 when recrystallizing 2 in methanol. Both 1 and 2 are high-spin species in the range of 1.8–300 K.     

Study of a gold electrode modified by trans-[Ru(NH3)4(Ist)SO4] to produce an electrochemical sensor for nitric oxide

The modification of a gold electrode surface by electropolymerization of trans-[Ru(NH₃)₄(Ist)SO₄]⁺ to produce an electrochemical sensor for nitric oxide was investigated. The influence of dopamine, serotonin and nitrite as interferents for NO detection was also examined using square-wave voltammetry (SWV). The characterization of the modified electrode was carried out by cyclic voltammetry, electrochemical quartz crystal microbalance (EQCM) and SERS techniques. The gold electrode was successfully modified by the trans-[Ru(NH₃)₄(Ist)SO₄]⁺ complex ion using cyclic voltammetry. The experiments show that a monolayer of the film is achieved after ten voltammetric cycles, that NO in solution can coordinate to the metal present in the layer, that dopamine, serotonin and nitrite are interferents for the detection of NO, and that the response for the nitrite is much less significant than the responses for dopamine and serotonin. The proposed modified electrode has the potential to be applied as a sensor for NO.     

Synthesis,structure and properties of a novel 3D pentanuclear [Zn5(OH)2]8 + cluster-based (3,4,11)-connected coordination polymer

A novel coordination polymer based on the multidentate N-donor ligand 1-((1H-1,2,4-triazol-1-yl)methyl)-3,5-bis(3-pyridyl)-1,2,4-triazole (3,3′-tmbpt) and 1,2,4,5-benzenetetracarboxylate anion (btec), namely, [Zn₅(3,3′-tmbpt)(btec)₂(OH)₂] (1), has been synthesized hydrothermally. Compound 1 displays a rare 3D (3,4,11)-connected framework based on a [Zn₅(OH)₂]^8 + cluster. The optical band gap and photoluminescent property of compound 1 have been studied.