Syntheses, structures, and redox properties of dimeric triruthenium clusters bridged by bis(diphenylphosphino)acetylene and -ethylene

Reactions of oxo-centered triruthenium acetate complexes [Ru3O(OAc)6(py)2(CH3OH)](PF6) (py = pyridine, OAc = CH3COO-) (1) with nearly equimolar amounts of dppa [bis(diphenylphosphino)acetylene] or dppen [trans-1,2-bis(diphenylphosphino)ethylene] gave [Ru3O(OAc)6(py)2(L)](PF6) (L = dppa, 2; dppen, 3). With 2.4 equiv of 1, the reactions provided diphosphine-linked triruthenium dimers, [[Ru3O(OAc)6(py)2]2(L)](PF6)2 (L = dppa, 4; L = dppen, 5), respectively. Similarly, the reactions of [Ru3O(OAc)6(L')2(MeOH)]+ [L' = dmap (4-(dimethylamino)pyridine), 1a; L' = abco (1-azabicyclo[2.2.2]octane), 1b] with dppen gave dppen-linked dimers, [[Ru3O(OAc)6(dmap)2]2(dppen)](SbF6)2 (6) and [[Ru3O(OAc)6(abco)2]2(dppen)](BF4)2 (7), respectively. The chemical reduction of 2, 4, and 5 by hydrazine afforded one- or two-electron-reduced, neutral products, Ru3O(OAc)6(py)2(dppa) (2a), [Ru3O(OAc)6(py)2]2(dppa) (4a), and [Ru3O(OAc)6(py)2]2(dppen) (5a), respectively. The complexes were characterized by elemental analyses, ES-MS, UV-vis, IR, and 31P NMR spectroscopies, and cyclic and differential-pulse voltammetries. The molecular structures of compounds 2, 4, 5, 5a, 6, and 7 were determined by single-crystal X-ray diffraction. In 0.1 M (Bu4N)PF6-acetone, the monomers and dimers of triruthenium clusters show reversible and multistep redox responses. The two triruthenium cluster centers in dimers undergo stepwise reductions and oxidations due to the identical redox processes of the individual Ru3O cluster cores, suggesting the presence of electronic communications between them through the conjugated diphosphine spacer. The redox wave splitting mediated by dppa containing an ethynyl group (C triple bond C) is found to be more extensive than that by dppen containing an ethenyl (C=C) one. It appears that the redox wave splitting is enhanced by the introduction of electron-donating substituents on the auxiliary pyridine rings.     

Optically active triosmium clusters containing the cysteine ligand

The reactions of cysteine ethyl ester with a series of triosmium clusters have been studied. Enantiomeric (-H)Os₃{-SCH₂CH(CO₂Et)NH₂}(CO)₁₀ and diastereomeric (-H)Os₃{-²-SCH₂CH(CO₂Et)NH₂}(CO)₉ forms of the optically active cluster complexes have been obtained. Diastereomeric clusters have been separated by TLC on Silufol plates. The treatment of the enantiomeric complex (-H)Os₃{-SCH₂CH(CO₂Et)NH₂}(CO)₁₀ with the trimethylamine oxide yields the diastereomeric pair (-H)Os₃{-²-SCH₂CH(CO₂Et)NH₂}(CO)₉. The structures of the complexes obtained have been established on the basis of IR,¹H NMR and mass spectrometry as well as X-ray analysis data.Translated fromIzyestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1981–1984, November, 1993.     

Synthesis and structural characterisation of novel linked bis(beta-diketiminato) rare earth metal complexes

Rare earth metal complexes based on novel linked bis(beta-diketiminato) ligands have been prepared via amine elimination and their structural characterisation revealed that the linker unit has significant influence on the geometry and coordination mode of the ancillary ligand.     

New bis(diphenylphosphino)aniline derivatives: Synthesis and spectroscopic characterization

Six new multidentate bis(diphenyl‐phosphino)amine [R–N(PPh₂)₂] ligands have been prepared from the reaction of aniline derivatives, R–NH₂, with Ph₂PCl in the presence of triethylamine. All of the compounds were obtained in good yields and were characterized by NMR, IR, and microanalysis. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:613–616, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20362     

Synthesis and characterisation of dialkyltin 2,3-bis(diphenylphosphino)maleic acid adducts

The novel dialkyltin 2,3-bis(diphenylphosphino)maleic acid adducts (R₂Sn)(O,O′-dpmaa) [1a, R = Me; 1b, R = Bu; dpmaa = bis(diphenylphosphino)maleic acid] were synthesised from dpmaa and R₂SnCl₂ or Bu₂SnO. They were fully characterised by elemental analysis, IR- and multinuclear NMR-spectroscopies as well as X-ray crystallography [in the case of 1a as its Ph₂P(O)(CH₂)₂P(O)Ph₂ adduct]. Both were found to be cyclic trimers in the solid state that dissolve in the case of 1b into an equilibrium mixture of oligomers.     

Synthesis and characterization of triosmium and triruthenium pyrene clusters

The reaction between 1-pyrenecarboxaldehyde (C₁₆H₉CHO) and the labile triosmium cluster [Os₃(CO)₁₀(CH₃CN)₂] gives rise to the formation of two new compounds by competitive oxidative addition between the aldehydic group and an arene C-H bond, to afford the acyl complex [Os₃(CO)₁₀(μ-H)(μ-COC₁₆H₉)] (1) and the compound [Os₃(CO)₁₀(μ-H) (C₁₆H₈CHO)] (2), respectively. Thermolysis of [Os₃(CO)₁₀(μ-H)(μ-C₁₆H₉CO)] (1) in n-octane affords two new complexes in good yields, [Os₃(CO)₉(μ-H)₂(μ-COC₁₆H₈)] (3) and the pyryne complex [Os₃(CO)₉(μ-H)₂(μ₃-η¹:η¹:η²-C₁₆H₈)] (4).In contrast, when 1-pyrenecarboxaldehyde reacts with [Ru₃(CO)₁₂] only one product is obtained, [Ru₃(CO)₉(μ-H)₂(μ₃-η¹:η¹:η²-C₁₆H₈)] (5), a nonacarbonyl cluster bearing a pyrene ligand. All compounds were characterized by analytical and spectroscopic data, and crystal structures for 1, 2, 4 and 5 were obtained.     

Synthesis and cytotoxicity of dinuclear complexes containing ruthenium(II) bipyridyl units linked by a bis(pyridylimine) ligand

Enantiopure dinuclear ruthenium polypyridyl complexes of the form [Ru(2)(LL)(4)L(1)](PF(6))(4) (LL = 2,2'-bipyridine (bpy) or 1,10-phenanthroline (phen); L(1)= C(25)H(20)N(4) a bis(pyridylimine) ligand containing a diphenylmethane spacer) have been synthesized using the chiral building blocks cis-[Ru(bpy)(2)(py)(2)](2+) and cis-[Ru(phen)(2)(py)(2)](2+). These dinuclear ruthenium complexes have been characterised using NMR, mass spectrometry, UV-visible absorbance, circular dichroism and linear dichroism. The compounds exhibit good photo and thermal stability. The extinction coefficient for the bpy complex at 478 nm is epsilon(478) = 15,700 mol(-1) cm(-1) dm(3) and for the phen complex is epsilon(478) = 24,900 mol(-1) cm(-1) dm(3). Both complexes have their longest wavelength (metal to ligand charge transfer) transition predominantly x/y (short axis)-polarised while the transitions at shorter wavelength are a mixture of x/y and z-polarisations, similar to both the copper helicate and iron triple helicate studied previously. Cytotoxicity studies reveal that the compounds are dramatically less active against cancer cell lines than the recently reported supramolecular cylinders prepared from the same bis(pyridylimine) ligand.     

Addition of dimethylphenylphosphine at bridging vinyl,acetylene and phenylacetylide ligands in triosmium clusters

PMe₂Ph readily adds at carbon in the compounds HO_S3 (CHCH₂)(CO)₁₀, HO_S3(CCPh)(CO)₁₀ and O_S3 (CHCH)(CO)₁₀ to give zwitterionic 1:1 adducts; the addition to the vinyl compound is reversible and further reaction leads to O_S3 (CO)₁₀ (PMe₂Ph)₂ with ethylene displacement.     

Theoretical study of the conformations of triosmium clusters with a chiral carane ligand

A theoretical study has been performed to investigate the conformations of triosmium clusters with a chiral carane ligand . The potential curves of internal rotation have been determined for organic ligands rotating around the S-C bond in the cluster complexes. The structures of possible conformers are analyzed along with reasons for their stability. The rotation barrier relative to the S-C bond is 439.8 kJ/mole, which hinders free rotation of ligands.Original Russian Text Copyright © 2004 by V. A. Potemkin V. A. Maksakov, and V. P. KirinTranslated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 3, pp. 430–434, May–June, 2004.     

Synthesis and Structure of Di［bis（diphenylphosphino）ethane］ Copper（Ⅱ） Dinitrate

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New octahedral bis(diphenylphosphino)methanide derivatives and heterometallic species from mixed ligand isocyanide-dppm iron(II) complexes

The cationic [FeL(dppm)(CNPh)₃]ⁿ⁺ (1a: L = I, n = 1; 1b: L = CNPh, n = 2) are readily deprotonated by KOH to give [FeL(dppm-H)(CNPh)₃]ⁿ⁻¹ (2a and 2b). 2a reacts with [thtAuPPh₃]PF₆ to give mer-[FeI((PPh₂)₂C(H)(AuPPh₃))-(CNPh)₃]PF₆ (3). The new heterotrimetallic species [FeL((PPh₂)₂C(AuPPh₃)₂)-(CNPh)₃]ⁿ⁺ (4a and 4b) have been obtained from 1a and 1b by treatment with ClAuPPh₃ in the presence of KOH.     

Synthesis and structural characterisation of novel platinum-based drug candidates with extended functionality by incorporation of bis(diphenylphosphino)ferrocene units as metal chelators

Among the metal-based anticancer drugs, cisplatin (cis-diaminedichloroplatinum(II)) is the most widely used species in therapy. Despite its clinical success, cisplatin still suffers in generating resistance, as well as being highly toxic due to poor selectivity between healthy and sick cells. By molecular design it ought to be possible to generate new cis-platinum compounds with increased selectivity and improved cellular behaviour. In this paper, we report a synthetic pathway for construction of derivatives of 1,1′-bis(diphenylphosphino)-ferrocene, together with their corresponding cis-platinum compounds with the aim testing them for their interaction capacity with respect to various DNA models. We also report a synthetic route for a nucleoside-based cis-platinum compound containing a bidentate ferrocenylphosphine derivative connected through a succinamic-based linker to the 5-position of the heterocyclic moiety of uridine. Our preliminary kinetic investigation of 5-{N-[1-[1′,2-bis(diphenylphosphino)ferrocenyl]ethyl]-N′-[prop-2-yn-3-yl]succinamide} uridinedichloroplatinum(II) showed that this compound reacted faster with the phosphorothioate containing oligonucleotides d(T₆p(S)T₆), with an observed first-order rate constant k_obs=(1.4±0.1)×10⁻⁴ s⁻¹, compared with the G-N7 target in d(T₇GGT₇), for which the observed first-order rate constant is k_obs=(7.2±0.5)×10⁻⁴ s⁻¹.     

Synthesis characterisation and stability of mixed aryldichalcogenide bis(diphenylphosphino)ethanenickel(II) complexes. X-ray structure of Ni(dppe)(SeC6H4S)

Mixed chalcogenide complexes of the type Ni(dppe)(SeC₆H₄S) (dppe=bis(diphenylphosphino)ethane), Ni(dppe)(SC₅H₃NCO₂) and Ni(dppe)(EC₅H₃NE′) (E=NH, E′=O; E=E′=NH) have been prepared from the reactions of Ni(dppe)Cl₂ with the appropriate aryldichalcogen or pyridine-based compound, using Et₃N as a base. The relative solution and thermal stabilities of the above compounds, other mixed chalcogen ones, Ni(dppe)(SC₆H₄O), Ni(dppe)(SC₆H₄CO₂) and Ni(dppe)(SC₆H₄NH), and the homoleptic compounds Ni(dppe)(EC₆H₄E′) (E=E′=O, E=E′=S; R=H, Me), were established by a combination of electron impact mass spectrometry (EIMS) and fast atom bombardment (FABMS). The most stable ones were the compounds with homoleptic sulfur ligands.     

Synthesis and characterisation of eight isomeric bis(2-pyridyloxy)naphthalenes

Eight isomeric bis(2-pyridyloxy)naphthalenes have been prepared from reactions of 2-bromopyridine with the appropriate dihydroxynaphthalene and the products fully characterised by 1- and 2-D NMR spectroscopy.     

Theoretical study of the conformational states of triosmium clusters with a chiral pinane ligand

A theoretical study of the conformational state of triosmium clusters with a chiral pinane ligand (μ-H)Os₃(CO)₁₀(μ-ONC₁₀H₁₄) has been performed. The potential curves of internal rotation of organic ligands around the N-C bond in cluster complexes in the crystalline state and in various solvents with continual consideration for the parameters of the latter have been determined. The structures of conceivable conformers and isomers are considered; the factors responsible for their formation and stability are examined. The relations between the conformational and crystalline structures of the cluster and the effect of intra-and intermolecular interactions on its structure are revealed.     

Rhodium(I) carbonyl complexes of mono selenium functionalized bis(diphenylphosphino)methane and bis(diphenylphosphino)amine chelating ligands and their catalytic carbonylation activity

The chelate complexes of the types (1) and (2) have been synthesized and characterized by IR and NMR spectroscopy. The lower shift of the ν(P-Se) bands and downfield shift of the ³¹P-{¹H}NMR signals for both P(III) and P(V) atoms in 1 and 2 compared to the corresponding free ligands indicate chelate formation through selenium donor. 1 and 2 show terminal ν(CO) bands at 1977 and 1981 cm⁻¹, respectively, suggesting high electron density at the metal center. The molecular structure of 2 has been determined by single-crystal X-ray diffraction. The rhodium atom is at the center of a square planar geometry having the phosphorus and selenium atoms of the chelating ligand at cis-position, one carbonyl group trans- to selenium and one chlorine atom trans- to phosphorus atom. 1 and 2 undergo oxidative addition (OA) reaction with CH₃I to produce acyl complexes (3) and (4), respectively. The kinetics of the OA reactions reveal that 1 undergoes faster reaction by about 4.5 times than 2. The catalytic activity of 1 and 2 in carbonylation of methanol was higher than that of the well known species [Rh(CO)₂I₂]⁻ and 2 shows higher catalytic activity compared to 1.     

Synthesis and properties of the chain-like polymeric copper (II) complexes bridged by bis(diphenylphosphino oxide)ethane

At room temperature, the chain-like polymeric copper (II) complexes bridged by bis (diphenylphosphino oxide) ethane (dppeO2), [Cu(dppeO2)X2]n[X=Cl(1), Br(2)] have been prepared and characterized by elemental analysis, 31P NMR, TG-DTA and X-ray analysis for [ CuBr2 (dppeO2) ] n The chain is composed of subunits containing tetrahedron coordinated copper (II) atoms. The four-coordinated copper (II) atom is ligated to another four-coordinated copper (II) atom through dppeO2. The coordination sphere of copper(II) atom is completed by two monodentate bromide and two oxygen atoms from bridging dppeO2. Crystal data are as follows: C26-H24CuP2BnO2, 0.50 mm× 0.40 mm×0.40 mm, monoclin-ic, space group: C2/c, λ= 0.07107 nm(Mo Ka), a = 1.2286(2) nm, b=2.0555(8) nm, c = 1.0652(2) nm, β = 97.366(9)°, V = 2.668nm3, Z = 4, Dcalc = 1.628 g·cm-3, R = 0.066; Rw = 0.091.     

Synthesis and coordination chemistry of a photoswitchable bis(phosphine) ligand

A 1,2-dithienylethene compound bearing bis(phosphine) groups (1o) represents a new class of photoresponsive ligands where there are steric and electronic differences between two photogenerated isomers. The coordination chemistry of this ligand class is demonstrated by preparing a gold(I) complex (2o) and a phosphine selenide (3o).