DMSO Ligands Research Articles

Lanthanide complexes in hybrid halometallate materials: interconversion between a novel 2D microporous framework and a 1D zigzag chain structure of iodoargentates templated by octakis-solvated terbium(III) cation

Octakis solvated terbium iodide complexes [Tb(DMSO)(8)]I(3) (1) and [Tb(DMF)(8)]I(3) (2) (DMSO = dimethylsulfoxide; DMF = dimethylformamide) were used as synthons to construct novel iodoargentate fabrics. Reaction of 1 with 6 equivalents of AgI in the presence of NH(4)I produced a novel framework compound [Tb(DMSO)(8)](2)[Ag(2)(mu-I)(3)I(2)][Ag(5)(mu(3)-I)(4)(mu-I)(4)](2infinity) (3) involving alternate layers of discrete [Tb(DMSO)(8)](3+) cation, [Ag(2)I(5)](3-) anion and a 2D microporous sheet of the composition [Ag(5)I(8)](3-), whereas similar reaction of 2 yielded [Tb(DMF)(8)][Ag(6)(mu(4)-I)(2)(mu(3)-I)(2)(mu-I)(5)](1infinity) (4) with a 1D zigzag structure. The two structural forms are completely inter-convertible on mutual exchange of DMSO and DMF ligands, the partial substitution of the former ligand in 3 yielding a mixed-ligand complex [Tb(DMF)(6.7)(DMSO)(1.3)][Ag(6)(mu(4)-I)(2)(mu(3)-I)(2)(mu-I)(5)](1infinity) (5). Single crystal X-ray structures are reported for all the complexes. Thermo-gravimetric analyses of these complexes show that thermal stability decreases in the order 4 > 2 > 3 > 1, whereas the diffuse reflectance spectra of 3 and 4 exhibit an optical band gap of about 3.7 eV, thus revealing the insulator nature of these hybrid iodoargentates. Compared to solvated terbium iodide complexes 1 and 2, the high energy transitions in the excitation spectra of the iodoargentate complexes 3 and 4 are quenched by a process which can best be attributed to the auto-ionization of the carriers in the above materials.

A combined experimental and theoretical investigation on the oxygenation of organic sulfides by oxo(salen)chromium(V) ion

AbstractThe mechanism of oxygenation of organic sulfide by oxo(salen)chromium(V) complexes has been studied experimentally and by the density functional theory (DFT) method. Spectral studies show DMSO ligands bind with the Cr center of oxidant and the adduct formed was responsible for the oxygenation reaction. The reaction was first order with respect to oxidant and substrate. Hammett plot shows the formation of positive charge over sulfur atom and the development of negative charge over the oxidant in the transition state (TS). For the substrate ρ values are in the range from −1.5 to −1.8. The geometry has been correctly predicted by the B3LYP function, and it gives better results for spin states, harmonic frequencies, and thermodynamic energies for the system. DFT results indicate the existence of oxo(salen)chromium(V) and Cr(III)–salen at doublet and quartet as ground state, respectively. Binding of donor ligand weakens the CrO bond. TS structures show an increase in the negative charge and spin density over Cr atom indicating the involvement of spin inversion and radical character. The low activation energy and high free energy change are responsible for the enhancement of the reaction rate and product yield in the presence of DMSO donor ligand, while the rebound mechanism and the direction of substrate approach perpendicular to the salen plane are responsible for their higher selectivity. From this combined study, a mechanism involving consecutive two‐electron transfer from the oxo(salen)chromium(V) ion to the electron‐rich sulfur atom is proposed. Copyright © 2008 John Wiley & Sons, Ltd.

Efficient C–S cross coupling catalyzed by Cu 2O

A protocol for the copper-catalyzed C–S bond formation between aryl, alkyl, or heteroaryl thiols and aryl or heteroaryl halides is reported. The reaction is catalyzed by Cu 2O which shows the highest catalytic activity with ethyl 2-oxocyclohexanecarboxylate ligand in DMSO at 80 °C. The corresponding coupling products are obtained with good to excellent yields under relatively mild reaction conditions with good chemoselectivity and functional group tolerance.

Dimolybdenum Bis-2,4,6-triisopropyl-benzoate Bis-4-isonicotinate: A Redox Active Analogue of 4,4′-Bipyridine with Ambivalent Properties

The reaction between Mo2(TiPB)4 and 4-iso-nicotinic acid (2 equiv) in ethanol leads to the formation of trans-Mo2(TiPB)2(nic)2, I, where TiPB = 2,4,6-triisopropylbenzoate and nic = 4-isonicotinate. The molecular structures of I and I x 2DMSO were determined in the solid state by a single-crystal X-ray study, and its electronic structure was determined by DFT calculations on a model compound, where formate ligands were substituted for the bulky TiPB. The physicochemical properties of I are reported, and its potential as a redox active building block, a quasi-metalloorganic analogue of 4,4'-bipyridine, is described in the synthesis of molecular and solid-state assemblies. The molecular structure of I in the solid state consists of a 3-dimensional network in which each unit of Mo2(TiPB)2(nic)2 acts as a donor and acceptor via N to Mo coordination. In the structure of I x 2DMSO, the DMSO ligands coordinate axially with the Mo-Mo bond via oxygen. The reaction between I and Rh2(O2CMe)4 is shown to give a 1-D polymeric chain in the solid state: [{Rh2(O2CMe)4}{Mo2(TiPB)2(nic)2}] infinity, II. A similar structure was found for the product involving Rh2(O2CCMe3)4. Evidence is also reported for the formation of [(1,5-COD)MePt]2[mu-Mo2(TiPB)2(nic)2](PF6)2, III, and [(1,5-COD)Pt(mu-I)(PF6)2]n.

Linkage isomerism of pentaammine(dimethylsulfoxide)ruthenium(II/III) complexes: A theoretical study

Density functional theory (DFT) calculations have been performed for understanding the linkage isomerism of [Ru II/III(NH 3) 5(dmso)] 2+/3+ (dmso = dimethylsulfoxide) from a theoretical point of view. In particular, we focus on the interchange between O-bonded and S-bonded structures of the dmso ligand by oxidation/reduction. We have examined five different exchange-correlation functionals (SVWN, BP86, mPWPW91, B3PW91, and B3LYP) in our DFT calculations and found that the relative stabilities of the O-bonded and S-bonded structures are largely dependent on the functional employed. From detailed analyses of atomic charge distributions, it has been found that the calculated atomic charges on the central metal ions are strongly correlated with the relative energies. We also studied the effect of solvation on the linkage isomerism using continuum solvation models.

Mechanistic theoretical insight of Ru(II) catalysts with a meridional–facial bpea fashion competition

A novel mechanistic insight for the interconversion between two octahedral ruthenium isomers, trans-mer-[RuIICl2(bpea)(dmso)], 2a, and cis-fac-[RuIICl2(bpea)(dmso)], 2b, (bpea=N,N-bis(2-pyridylmethyl)ethylamine) is reported. The isomer 2a displaying the bpea ligand in a meridional fashion is kinetically favoured with respect to 2b, with the bpea ligand in a facial fashion, which is the thermodynamically favoured one. The dissociative mechanism with the cleavage of a chloro ligand as starting point becomes more feasible with respect to the intramolecular mechanism. However, DFT calculations make competitive the mechanism which dissociates first the dmso ligand. Thus, a further characterisation of all the reaction pathways for the interconversion 2a→2b has been fulfilled.

The reduction of (ImH)[trans-RuIIICl4(dmso)(Im)] under physiological conditions: preferential reaction of the reduced complex with human serum albumin

A systematic study of the reduction of (ImH)[trans-RuCl(4)(dmso)(Im)] (NAMI-A; dmso is dimethyl sulfoxide, Im is imidazole), a promising antimetastasing agent, by L-ascorbic acid under physiological conditions is reported. Under blood plasma conditions (pH 7.4, 0.1-0.15 M NaCl , 37 degrees C) the rapid reduction of trans-[Ru(III)Cl(4)(dmso)(Im)](-) results in the formation of trans-[Ru(II)Cl(4)(dmso)(Im)](2-) within seconds, and is followed by successive dissociation of the chloride ligands, whereas neither dmso nor imidazole ligands are released during the reaction. Under our experimental conditions, the formation of the ascorbate dianion is the rate-determining step, and once it has formed it reacts rapidly with NAMI-A. Moreover, the NAMI-A complex is very unstable at physiological pH (7.4); therefore, the hydrolysis of NAMI-A cannot be excluded as a competing reaction. During hydrolysis, aquated derivatives via stepwise dissociation of chloride and dmso ligands are formed, and most of these species have a higher redox potential and are expected to be even more easily reduced by ascorbic acid. Thus, it is very likely that the reduced form of NAMI-A or the reduction products of its hydrolytic derivatives react with albumin. The reaction of reduced NAMI-A with human serum albumin leads to the formation of stable adducts, with a binding efficiency very similar to that of the parent complex, viz., 3.2+/-0.3 and 4.0+/-0.4 mol of Ru(II) and Ru(III) per mole of albumin, respectively, however with a significantly higher reactivity.

Cis-Dicyanoosmium(II) Diimine Complexes Bearing Phosphine or Sulfoxide Ligands: Spectroscopic and Luminescent Studies

A series of cis-dicyanoosmium(II) complexes [Os(PPh3)2(CN)2(N intersectionN)] (N intersectionN = Ph2phen (2a), bpy (2b), phen (2c), Ph2bpy (2d), tBu2bpy (2e)) and [Os(DMSO)2(CN)2(N intersectionN)] (3a-3e, N intersectionN = Br2phen (3f), Clphen (3g)), were synthesized and their spectroscopic and photophysical properties were examined, and [Os(PMe3)2(CN)2(phen)] (4) with axial PMe3 ligands was similarly prepared. The molecular structures of 2a, 2c, [2c.Zn(NO3)2]infinity, 2d, 2e, 3b, 3d, 3e, and 4 were determined by X-ray crystallographic analyses. The two CN ligands are cis to each other with mean Os-C bond distance of 2.0 A. The two PR3 (R = Ph, Me) or DMSO ligands are trans to each other with P/S-Os-P/S angles of approximately 177 degrees . The UV-vis absorption spectra of 2a-2e display an intense absorption band at 268-315 nm (epsilon = approximately (1.54-4.82) x 104 M-1 cm-1) that are attributed to pi --> pi*(N intersection N) and/or pi --> pi*(PPh3) transitions. The moderately intense absorption bands with lambdamax at 387-460 nm (epsilon = approximately (2.4-11.3) x 103 M(-1) cm(-1)) are attributed to a 1MLCT transition. A weak, broad absorption at 487-600 nm (epsilon = approximately 390-1900 M(-1) cm(-1)) is assigned to a 3MLCT transition. Excitation of 2a-2e in dichloromethane at 420 nm gives an emission with peak maximum at 654-703 nm and lifetime of 0.16-0.67 micros. The emission energies, lifetimes, and quantum yields show solvatochromic responses, and plots of numax, tau, and Phi, respectively, versus ET (solvent polarity parameter) show linear correlations, indicating that the emission is sensitive to the local environment. The broad structureless solid-state emission of 2a-2e at 298 (lambdamax 622-707 nm) and 77 (lambdamax 602-675 nm) K are assigned to 3MLCT excited states. The 77 K MeOH/EtOH (1:4) glassy solutions of 2a-2e also exhibit 3MLCT emissions with lambdamax = 560-585 nm. The 1MLCT absorption and 3MLCT emission of 3a-3g occur at lambdamax = 332-390 nm and 553-644 nm, respectively. In the presence of Zn(NO3)2, both the 1MLCT absorption and 3MLCT emission of 2c in acetonitrile blue-shift from 397 to 341 nm and 651 to 531 nm, respectively. The enhancement of emission intensity (I/Io) of 2e at 531 nm reached a maximum of approximately 810 upon the addition of two equivs of Zn(NO3)2. The crystallographic and spectroscopic evidence suggests that 2c undergoes binding of Zn2+ ions via the cyano moieties.

Mechanistic Insights into the Chemistry of Ru(II) Complexes Containing Cl and DMSO Ligands

Two new isomers trans,mer-[RuIICl2(bpea)(DMSO)], 2a, and cis,fac-[RuIICl2(bpea)(DMSO)], 2b, (bpea = N,N-bis(2-pyridylmethyl)ethylamine), as well as the bis-DMSO complex trans,fac-[RuIICl(bpea)(DMSO)2]Cl, 3, have been synthesized and characterized by cyclic voltammetry and UV-vis and 1D and 2D NMR spectroscopy in solution. Their solid-state structure has also been solved by means of single-crystal X-ray diffraction analysis. All the three complexes display a ruthenium metal center possessing a distorted-octahedral type of coordination, where the bpea ligand is coordinated in a meridional fashion in 2a and in a facial fashion in 2b and 3. The isomer 2a is the kinetically favored and thus can be thermally converted into 2b, that is the thermodynamically favored one. A thorough kinetic analysis strongly points toward a dissociative mechanism, where in the first step a chloro ligand is removed from the metal coordination sphere, followed by a geometric rearrangement before the chloro ligand coordinates again, generating the final complex. DFT calculations agree with the experimental data for the proposed mechanism and allow us to further characterize the mechanism of the 2a --> 2b rearrangement by obtaining the intermediates and transition state.

Synthesis of Mixed NHC/L Platinum(II) Complexes: Restricted Rotation of the NHC Group

The use of (NHC)AgX salts as transmetallating agents for platinum can be tuned to introduce either one or two NHC ligands per platinum in high yield. Complexes with a single NHC ligand are prepared with an additional DMSO ligand, which can conveniently be replaced by other ligands such as phosphines to give mixed cis NHC/phosphine complexes. Variable-temperature NMR and DFT have been used to probe the nature of the restricted rotation of the NHC ligand about the square planar platinum center: experimentally, the barrier has been established as at least 85 kJ mol-1, and the computational value has been determined to be 92 kJ mol-1.

Double cyclometallation of bridging 3,6-bis(2-thienyl)-1,2,4,5-tetrazine in a dinuclear mesityl(dimethylsulfoxide)platinum(II) complex: Structure and properties

3,6-Bis(2-thienyl)-1,2,4,5-tetrazine (bttz) reacts with trans-Pt(dmso) 2(mes) 2, mes = mesityl = 2,4,6-trimethylphenyl, under twofold cyclometallation to yield structurally characterized (μ-bttz-2H +)[Pt(dmso)(mes)] 2 with uncoordinated thiophene sulfur atoms and bttz deprotonated in the 3,3′ positions. The structural features include cis-positioned carbanionic ligands, twisted mesityl substituents, S-coordinated dmso ligands with the S O bonds lying in the molecular plane, shortened inter-ring bonds, and rather short Pt–C bonds at 1.998(9)/2.00(1) Å (Pt–C mes) and 1.985(9)/1.99(1) Å (Pt–C bttz-2H+). Reversible reduction to {(μ-bttz-2H +)[Pt(dmso)(mes)] 2} − causes a high-energy shift of the charge transfer bands and the appearance of an unresolved EPR signal at g = 1.9905.

Phase transition and thermal decomposition of [Al(DMSO)6]Cl3

Phase transition and thermal decomposition of hexadimethylsulfoxidealuminium chloride were studied by differential scanning calorimetry (DSC), thermogravimetry (TG) and simultaneous differential thermal analysis (SDTA). The gaseous products of the decomposition were on-line identified by a quadrupole mass spectrometer (QMS). In the temperature range of 95–300 K, [Al(DMSO)6]Cl3 indicates one phase transition at Tch=244.96 K (on heating) and at Tcc=220.87 K (on cooling). Large thermal hysteresis of the phase transition (∼24 K) indicates its first order character. Large value of transition entropy (ΔS≈40 J mol−1 K−1) suggests its configurational character. Thermal decomposition of the title compound proceeds in four main stages. In the first stage, which starts just above ca. 300 K, the compound loses two DMSO molecules per one formula unit and undergoes into [Al(DMSO)4]Cl3. In the second stage, the next three DMSO ligands are released and simultaneously decomposed. The third stage, which continues up to ca. 552 K, is connected with a loss of the last DMSO ligand and the formation of AlCl3. In the fourth stage AlCl3 reacts with carbon monoxide that originates from the decomposition of DMSO, and first aluminium oxychloride and next solid Al2O3 plus carbon are created.

Synthesis, Structure, and Reactivity of Diazoketiminato Complexes of Platinum(II) and Palladium(II): Cytotoxic Properties of a Platinum Complex

AbstractReaction of the 2‐(arylazo)anilines Ar‐N=N‐C6H4NH2 [HLnNH2; Ar = C6H5 (HL1), p‐CH3C6H4 (HL2), p‐ClC6H4 (HL3)] with K2PtCl4 in dmso affords the new PtII azoimine complexes [(HLnNH)Pt(dmso)Cl] where the chloride and dmso ligands are mutually cis. In contrast, treatment of Na2PdCl4 with HLnNH2 in dmso gives the chloro‐bridged palladium dimer [{(HLnNH)PdCl}2] as the major product along with [(HLnNH)2Pd] as the minor product. Further, the reaction of HLnNHCH2Ph with K2PtCl4 in dmso also gives [(HLnNH)Pt(dmso)Cl] whereas Na2PdCl4 affords the orthopalladated complexes [(LnNHCH2Ph)PdCl]. This means that the N–C(CH2Ph) bond is selectively cleaved by K2PtCl4. The reaction of [(HLnNH)Pt(dmso)Cl] with acetylacetone (acacH) gives the heteroleptic complex [(HLnNH)Pt(acac)]. [(HLnNH)Pt(dmso)Cl] and [(HLnNH)Pt(acac)] display a reversible reductive response at –1.20 and –1.46 V vs. SCE, respectively, in their cyclic voltammograms. The nature of the redox orbitals has been determined semi‐empirically employing the EHMO method. The cytotoxicity of [(HL1NH)Pt(dmso)Cl] has been examined with HeLa cells and the sub‐lethal dose (8 μM) determined by dose‐dependence studies. The relative degree of apoptotic and necrotic cell death using a sub‐lethal dose were measured by flow cytometry.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

X-ray Absorption Fine Structure Spectroscopic Studies of Octakis(DMSO)lanthanoid(III) Complexes in Solution and in the Solid Iodides

Octakis(DMSO)lanthanoid(III) iodides (DMSO = dimethylsulfoxide), [Ln(OS(CH3)2)8]I3, of most lanthanoid(III) ions in the series from La to Lu have been studied in the solid state and in DMSO solution by extended X-ray absorption fine structure (EXAFS) spectroscopy. L3-edge and also some K-edge spectra were recorded, which provided mean Ln-O bond distances for the octakis(DMSO)lanthanoid(III) complexes. The agreement with the average of the Ln-O bond distances obtained in a separate study by X-ray crystallography was quite satisfactory. The crystalline octakis(DMSO)lanthanoid(III) iodide salts have a fairly broad distribution of Ln-O bond distances, ca. 0.1 A, with a few disordered DMSO ligands. Their EXAFS spectra are in excellent agreement with those obtained for the solvated lanthanoid(III) ions in DMSO solution, both of which show slightly asymmetric distributions of the Ln-O bond distances. Hence, all lanthanoid(III) ions are present as octakis(DMSO)lanthanoid(III) complexes in DMSO solution, with the mean Ln-O distances centered at 2.50 (La), 2.45 (Pr), 2.43 (Nd), 2.41 (Sm), 2.40 (Eu), 2.39 (Gd), 2.37 (Tb), 2.36 (Dy), 2.34 (Ho), 2.33 (Er), 2.31 (Tm), and 2.29 A (Lu). This decrease in the Ln-O bond distances is larger than expected from the previously established ionic radii for octa-coordination. This indicates increasing polarization of the LnIII-O(DMSO) bonds with increasing atomic number. However, the S(1s) electron transition energies in the sulfur K-edge X-ray absorption near-edge structure (XANES) spectra, probing the unoccupied molecular orbitals of lowest energy of the DMSO ligands for the [Ln(OS(CH3)2)8](3+) complexes, change only insignificantly from Ln = La to Lu. This indicates that there is no appreciable change in the sigma-contribution to the S-O bond, probably due to a corresponding increase in the contribution from the sulfur lone pair to the bonding.

Crystallographic and Vibrational Spectroscopic Studies of Octakis(DMSO)lanthanoid(III) Iodides

The octakis(DMSO) (DMSO = dimethylsulfoxide) neodymium(III), samarium(III), gadolinium(III), dysprosium(III), erbium(III), and lutetium(III) iodides crystallize in the monoclinic space group P21/n (No. 14) with Z = 4, while the octakis(DMSO) iodides of the larger lanthanum(III), cerium(III), and praseodymium(III) ions crystallize in the orthorhombic space group Pbca (No. 61), Z = 8. In all [Ln(OS(Me2)8]I3 compounds the lanthanoid(III) ions coordinate eight DMSO oxygen atoms in a distorted square antiprism. Up to three of the DMSO ligands were found to be disordered and were described by two alternative configurations related by a twist around the metal-oxygen (Ln-O) bond. To resolve the atomic positions and achieve reliable Ln-O bond distances, complete semirigid DMSO molecules with restrained geometry and partial occupancy were refined for the alternative sites. This disorder model was also applied on previously collected data for the monoclinic octakis(DMSO)yttrium(III) iodide. At ambient temperature, the eight Ln-O bond distances are distributed over a range of about 0.1 A. The average value increases from Ln-O 2.30, 2.34, 2.34, 2.36, 2.38, 2.40 to 2.43 A (Ln = Lu, Er, Y, Dy, Gd, Sm, and Nd) for the monoclinic [Ln(OSMe2)8]I3 structures, and from 2.44, 2.47 to 2.49 A (Ln = Pr, Ce, and La) for the orthorhombic structures, respectively. The average of the La-O and Nd-O bond distances remained unchanged at 100 K, 2.49 and 2.43 A, respectively. Despite longer bond distances and larger Ln-O-S angles, the cell volumes are smaller for the orthorhombic structures (Ln = Pr, Ce, and La) than for the monoclinic structure with Ln = Nd, showing a more efficient packing arrangement. Raman and IR absorption spectra for the [Ln(OS(CH3)2)8]I3 (Ln = La, Ce, Pr, Nd, Gd, Tb, Dy, Er, Lu, and Y) compounds, also deuterated for La and Y, have been recorded and analyzed by means of normal coordinate methods. The force constants for the Ln-O and S-O stretching modes in the complexes increase with decreasing Ln-O bond distance and show increasing polarization of the bonds for the smaller and heavier lanthanoid(III) ions.

Mono- vs Bis(carbene) Complexes: A Detailed Study on Platinum(II)−Benzimidazolin-2-ylidenes

The reaction of PtBr2 with NaOAc and 1,3-diisopropylbenzimidazolium bromide (A) in DMSO afforded the mixed monocarbene−DMSO complex cis-[PtBr2(DMSO)(iPr2-bimy)] (cis-1) and the bis(carbene) complex trans-[PtBr2(iPr2-bimy)2] (trans-2). The DMSO ligand in cis-1 can be easily replaced by stronger donors such as triphenylphosphine and pyridine to give novel benzannulated monocarbene complexes trans-[PtBr2(iPr2-bimy)(PPh3)] (trans-3), cis-[PtBr2(iPr2-bimy)(PPh3)] (cis-3), and trans-[PtBr2(iPr2-bimy)(Pyridine)] (trans-4), respectively. All compounds have been fully characterized by multinuclei NMR spectroscopies and mass spectrometry (ESI, FAB). X-ray diffraction studies on single crystals of cis-1, trans-2, cis-3, and trans-4 revealed a square-planar geometry and a fixed orientation of the N-isopropyl substituents with the C−H protons pointing to the metal center to maximize interesting and rare C−H···Pt preagostic interactions. These interactions are also retained in solution, as indicated by the large downfield shift of the isopropyl C−H protons in the 1H NMR spectrum compared to that in the precursor salt A.

Rarely Decorated Rutile Frameworks Built from Triangular Organic Spacers and Distorted Octahedral Co 3 Building Blocks

Under mild temperatures, the self-assembly of CoCl2 and H3BTC in a solution of dmso generates a guest-free metal–organic polymer, namely Co3(BTC)2(μ1-dmso)2(μ2-dmso)2(1: dmso = dimethylsulfoxide, H3BTC = 1,3,5-benzenetricarboxylic acid). In 1, the CoII ions show the six-coordinate octahedral geometry completed by the BTC3– ions and the dmso oxygen atoms; remarkably, the coordinated dmso ligands not only act as terminal ligands to complete the octahedral geometry of the CoII ions, but also play an important role in bridging CoII ions together to give the Co3 secondary building units (SBUs). From a topological viewpoint, this novel polymer is classified to be the decorated (3,6)-connected rutile net with the (4.62)2(42.610.83) topology, where BTC3– ligands and Co3 SBUs are viewed to be the 3- and 6-connected nodes, respectively. In addition, the magnetic properties of 1 are explored by using a linear trinuclear cobalt mode, thusleading to g = 2.41, J = –34.92 cm–1, TIP = 340 × 10–6 cm3 mol–1,θ = –6 K (a θ parameter was included to take into account intertrinuclear interactions).(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

Syntheses and Crystal Structures of Mono(di-2-pyridylamine)chloro(dimethyl sulfoxide-S)ruthenium(II) Complexes [RuCl2(Hdpa)(dmso-S)2] and [RuCl(Hdpa)(dmso-O)(dmso-S)2](OTf)

Abstract The reaction between trans-[RuCl2(dmso-S)4] (dmso = dimethyl sulfoxide) and di-2-pyridylamine (Hdpa) in EtOH–H2O at ca. 273 K afforded trans(Cl),cis(S)-[RuCl2(Hdpa)(dmso-S)2] (1) in moderate to high yield. When dissolved in DMSO, 1 rearranged to the more thermodynamically stable cis(Cl),cis(S)-[RuCl2(Hdpa)(dmso-S)2] (2), along with cis(Cl),trans(X)-[RuCl2(Hdpa)(dmso)2] (X = S- or O-bonded dmso). The reaction of 2 with Ag(OTf) afforded cis(Cl,S),trans(O,S)-[RuCl(Hdpa)(dmso-O)(dmso-S)2](OTf) (3·(OTf)) (OTf− = trifluoromethanesulfonate). X-ray crystal structures of 1, 2, and 3·(OTf) revealed that the conformation of the six-membered chelate ring formed by the Hdpa ligand with the Ru ion varies according to interactions among the co-ligands (dmso and Cl−) and the counter-anion (OTf−). For 3·(OTf), the structural parameters, apart from the dmso-O ligand, were essentially comparable to those of 2, except for the axial Cl− ligand; the remaining axial site is occupied by the O-donor of the dmso ligand instead of the S-donor. The solution structures (in DMSO solution) of 1, 2, and 3·(OTf) are discussed on the basis of their 1H NMR spectra. In 3·(OTf), “flapping” of the Hdpa ligand causes the coordination modes (O- and S-bonded) of the two axial dmso ligands to undergo mutual alternation.

Polynuclear 3d complexes based on potentially tetra-anionic heptadentate ligands including amido, amino and phenoxo donors: Synthesis, crystal structure and magnetic properties

The synthesis and characterization of new dinuclear Mn III and tetranuclear Cu II complexes, [HL 1Mn(DMSO)] 2 ( 1) and [H 2L 2Cu 2(MeO) 2] 2 ( 2), are reported (H 4L 1 = 2-hydroxy- N-[2-({2-[(2-hydroxybenzoyl)amino]ethyl}amino)ethyl]benzamide and H 4L 2 = 2-hydroxy- N-[3-({3-[(2-hydroxybenzoyl)amino]propyl}(methyl)amino)propyl]benzamide). Single crystal X-ray structures have been determined for 1 and 2. In 1 only one of the two amide functions of H 4L 1 is deprotonated in addition to the phenol ones, while in 2 all the amide functions of H 4L 2 are protonated and none of the potential nitrogen donors (amide and amine) is involved in the coordination to copper. HL 1 and H 2L 2 do not play the role of compartmental ligands and do not wrap around one Mn and one Cu ion, respectively, but embrace two metal centers yielding, with the respective assistance of auxiliary DMSO and methoxo ligands, dinuclear manganese and tetranuclear copper complexes, respectively. 1 includes two well isolated Mn III ions (Mn⋯Mn′ = 7.33 Å) that do not interact magnetically. The intermolecular Mn⋯Mn″ distance along the 1D chains (10.17 Å) is also too large to allow extended magnetic interactions. The pairwise magnetic interactions between the copper(II) ions in the tetranuclear complex 2 are so large that the χ M T product is already equal to zero at room temperature, implying that the antiferromagnetic interaction is around −1000 cm −1, as observed previously for di-μ-hydroxo–dicopper complexes.

Ruthenium(II) Complexes Containing Bis(2-(diphenylphosphino)phenyl) Ether and Their Catalytic Activity in Hydrogenation Reactions

The half-sandwich complexes [(eta5-C5H5)RuCl(DPEphos)] (1) and [{(eta6-p-cymene)RuCl2}2(mu-DPEphos)] (2) were synthesized by the reaction of bis(2-(diphenylphosphino)phenyl) ether (DPEphos) with a mixture of ruthenium trichloride trihydrate and cyclopentadiene and with [(eta6-p-cymene)RuCl2]2, respectively. Treatment of DPEphos with cis-[RuCl2(dmso)4] afforded fac-[RuCl2(kappa3-P,O,P-DPEphos)(dmso)] (3). The dmso ligand in 3 can be substituted by pyridine, 2,2'-bipyridine, 4,4'-bipyridine, and PPh3 to yield trans,cis-[RuCl2(DPEphos)(C5H5N)2] (4), cis,cis-[RuCl2(DPEphos)(2,2'-bipyridine)] (5), trans,cis-[RuCl2(DPEphos)(mu-4,4'-bipyridine)]n (6), and mer,trans-[RuCl2(kappa3-P,P,O-DPEphos)(PPh3)] (7), respectively. Refluxing [(eta6-p-cymene)RuCl2]2 with DPEphos in moist acetonitrile leads to the elimination of the p-cymene group and the formation of the octahedral complex cis,cis-[RuCl2(DPEphos)(H2O)(CH3CN)] (8). The structures of the complexes 1-5, 7, and 8 are confirmed by X-ray crystallography. The catalytic activity of these complexes for the hydrogenation of styrene is studied.