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This research experimentally measured the solubility of 2-aminoterephthalic acid in eight pure alcoholic solvents - methanol, ethanol, 1-propanol, 1-butanol, 2-propanol, 2-butanol, 2-methyl-2-propanol, and 3-methyl-1-butanol - from 303.15 to 338.15 K at normal pressure p = 0.1 MPa by the excess solid method. The measured solubility of 2-aminoterephthalic acid in these pure organic solvents was found to increase with the rise of temperature in the following order: 3-methyl-1-butanol (lowest solubility) < 1-butanol < 2-butanol < 1-propanol < 2-methyl-2-propanol approximate to 2-propanol < ethanol < methanol (highest solubility). The experimental solubility was correlated by the Van't Hoff equation and the lambda h (Buchowski) equation. The apparent thermo-dynamic properties (Delta 0Gsol, Delta 0Hsol and Delta 0Ssol) were calculated by the Van't Hoff equation, from which it was concluded that the dissolution process is entropy-motivated and endothermal. In addition, the solvent effects on 2-aminoterephthalic acid solubility were studied by the KAT-LSER model, where the results showed that the polarizability accounts for 47.9 +/- 4.2 % of the total solvent effect.A volcano-type relation between the dissolution entropy and enthalpy versus the solvent boiling point is re-ported, showing maximal values of 55.3 J mol-1 K-1 and 29.2 kJ mol-1, respectively, for intermediate molecular interactions of solute and solvent.

N,N '-bis(aniline)glyoxime (H2L, 1) has been prepared from aniline and (E,E)-dichloroglyoxime (DCGO) or (E,E)-dibromoglyoxime (DBGO). The reaction of N,N '-bis(aniline)glyoxime (H2L, 1) with solution of PtCl2 in dimethylsulfoxide produced brown-colored bis(E,E-dioximato)platinum(II) complex {[(E,E)-Pt(HL)(2)]} (1a) featuring N-chelating ligand. The crystal structure of this complex has been identified by X-ray diffraction on a single-crystal. In vitro assay of proliferation, cell death, DNA-damage and cell uptake activities of 1 and 1a were tested in HCC cell lines, SNU-182 and HUH-7. 1a has an anti-proliferative effect in HCC cells, however, 1 did not. Furthermore, the cellular uptake of 1a was relatively high compared to cisplatin cellular platinum levels. Compatible with proliferation and cellular uptake results, treatment with 1a caused DNA-damage and subsequent apoptosis in both HCC cell lines. Research Fund of the Gebze Technical University (BAP) [2018-A108-72] This work was financially supported by Research Fund of the Gebze Technical University (BAP, Project Number: 2018-A108-72).

A study of phase transitions of photochromic p,p’-n-alkylazobenzenes compounds was carried out by means of adiabatic scanning calorimetry (ASC) and photopyroelectric calorimetry (PPE) techniques, yielding accurately the temperature dependence of the enthalpy and of the specific heat capacity across the observed phase transitions, and the corresponding enthalpy of transition values. In addition, polarization microscopy imaging of the sample texture was performed together with the PPE calorimetric evaluations to establish the nature of the involved phases. By performing PPE calorimetric evaluations during UV irradiation of the samples, the influence of the photoinduced trans to cis isomerization of the nAB molecules on the occurrence of the phase transitions was assessed.

Direct spectroscopic evidence of a reaction occurring between acrolein and water and involving the exchange of an oxygen atom has been obtained by characterizing the non-covalently bound water complexes and their isotopic forms, via rotational spectroscopy. The experimental geometries of the binary and ternary water complexes have been determined, and other stationary points on the reaction path have been characterized using ab initio quantum chemical methods at the MP2/6-311++G(d,p) level. These results can enhance the understanding of the water-mediated atmospherically important reactions involving acrolein.

International audience; The coupling of the crystallographic refinement technique Hirshfeld atom refinement (HAR) with the recently constructed libraries of extremely localized molecular orbitals (ELMOs) gives rise to the new quantum-crystallographic method HAR-ELMO. This method is significantly faster than HAR but as accurate and precise, especially concerning the free refinement of hydrogen atoms from X-ray diffraction data, so that the first fully quantum-crystallographic refinement of a protein is presented here. However, the promise of HAR-ELMO exceeds large molecules and protein crystallography. In fact, it also renders possible electron-density investigations of heavy elements in small molecules and facilitates the detection and isolation of systematic errors from physical effects.

The compound [Cu(µ-Pip)(µ-OAc)(MeOH)]2 (1) (Pip = Piperonylate, OAc = acetate, MeOH = methanol) has been obtained in high percentage yield. Its reactivity with pyridine/pyrazole derivative ligands (pyridine (py), 3-phenylpyridine (3-Phpy) and 4-acetylpyridine (4-Acpy)) and 3,5-dimethylpyrazole (3,5-dmpz) leads to four monomeric compounds: [Cu(Pip)2(dPy)2(H2O)] (dPy = py (2), 3-Phpy (3) and 4-Acpy (4a)) and [Cu(Pip)2(3,5-dmpz)2] (5). Furthermore, the reaction of 1 with HPip in MeOH:DMF solvent under reflux conditions yields the homoleptic core paddle-wheel compound [Cu(µ-Pip)2(DMF)]2·2DMF (6). The reaction between 6 and 2-benzylpyridine (2-Bzpy) yields the paddle-wheel core compound [Cu(Pip)2(2-Bzpy)]2 (7). All compounds have been fully characterized by analytical and spectroscopic techniques and their X-ray crystal structures have been determined. In this set of compounds, the carboxylate ligand (Pip) displays different coordination modes (monodentate (2–4), bidentate chelate (5) and bridged (1, 6 and 7)). Moreover, their extended structures are discussed: the crystal packing indicates hydrogen bond propagation, which defines 1D (2–5) or 2D (6 and 7) supramolecular networks., This work was financed by the Spanish National Plan of Research MAT2015-65756-R, CTQ2016-75150-R and 2017SGR1687, 2014SGR149 projects from the Generalitat de Catalunya for its financial support.

While several reviews have been devoted to lower (ethylene and propylene) olefin polymerisation, several other substrates catalysed by vanadium complexes have escaped review. Here, vanadium-based complexes, active as (pre-)catalysts in the polymerisation of higher olefins, ring-opening metathesis polymerisation (ROMP) of alkenes, and ring-opening polymerisation (ROP) of lactones are reviewed. The Ziegler-Natta systems and some oxovanadium and vanadocene single-site pre-catalysts active towards styrene polymerisation are also mentioned. Furthermore, imidovanadium(V) complexes catalysing ROMP with ligands including aryl, aryloxy, and ketimide substituents are thoroughly reviewed and their activities and yields are compared. The ROP of lactides and e-caprolactone is also discussed.

The diazoalkane complexes [Ru(η(5)-C5Me5)(N2CAr1Ar2){P(OR)3}L]BPh4 (1-4) [R = Me, L = P(OMe)3 (1); R = Et, L = P(OEt)3 (2); R = Me, L = PPh3 (3); R = Et, L = PPh3 (4); Ar1 = Ar2 = Ph (a); Ar1 = Ph, Ar2 = p-tolyl (b); Ar1Ar2 = C12H8 (c); Ar1 = Ph, Ar2 = PhC(O) (d)] and [Ru(η(5)-C5Me5){N2C(C12H8)}{PPh(OEt)2}(PPh3)]BPh4 (5c) were prepared by allowing chloro-compounds RuCl(η(5)-C5Me5)[P(OR)3]L to react with the diazoalkane Ar1Ar2CN2 in the presence of NaBPh4. Treatment of complexes 1-4 with H2O afforded 1,2-diazene derivatives [Ru(η(5)-C5Me5)(η(2)-NH═NH){P(OR)3}L]BPh4 (6-9) and ketone Ar1Ar2CO. A reaction path involving nucleophilic attack by H2O on the coordinated diazoalkane is proposed and supported by density functional theory calculations. The complexes were characterized spectroscopically (IR and (1)H, (31)P, (13)C, (15)N NMR) and by X-ray crystal structure determination of [Ru(η(5)-C5Me5)(N2CC12H8){P(OEt)3}2]BPh4 (2c) and [Ru(η(5)-C5Me5)(η(2)-NH═NH){P(OEt)3}2]BPh4 (7).

International audience; synthesized and characterized by H-1, C-13, P-31 NMR and IR spectroscopies. The reaction of MnCl2 center dot 4H(2)O with L led to the formation of a new 3D system {MnL2Cl2}(n)center dot 34CH(3)OH (C-1). X-ray crystallographic data revealed that the ligand binds to the neighboring manganese ions through the nitrogen atom of pyridine (N-py) and the oxygen atom of phosphoryl (O-P) in a bidentate manner. The Mn(II) centers showed a distorted cis(N-py, N-py) cis(O-P, O-P) cis(Cl, Cl) octahedral configuration. In order to compare the relative stability of C-1 (with all-cis configuration) and its possible all-trans isomer, C-1', density functional theory (DFT) calculations were performed and the results showed the preference of C-1 over C-1' from energy point of view. Quantum theory of atoms in molecules (QTAIM) analysis was applied to elucidate the nature of interactions, and the results suggested an ionic character (closed-shell interaction) for Mn-OP bond, and a partial covalent contribution for Mn-N-py interaction. Natural bond orbital (NBO) analysis was also used to calculate the charge distribution on atoms in the complex. The complex C-1 showed efficient catalytic activity in the oxidation reaction of some alkenes to their corresponding epoxides. In addition, the effect of temperature and reaction time on the conversion and selectivity of cyclohexene epoxidation reaction in the presence of C-1 as catalyst was investigated. (C) 2015 Elsevier B.V. All rights reserved.

Succinic acid, a dicarboxylic acid molecule, has been investigated spectroscopically with computational support to elucidate the complex aspects of its conformational composition. Due to the torsional freedom of the carbon backbone and hydroxy groups, a large number of potentially plausible conformers can be generated with an indication that the gauche conformer is favored over the trans form. The microwave and millimeter wave spectra have been analyzed and accurate spectroscopic constants have been derived that correlate best with those of the lowest energy gauche conformer. For an unambiguous conformational identification measurements were extended to the monosubstituted isotopologues, precisely determining the structural properties. Besides bond distances and angles, particularly the dihedral angle has been determined to be 67.76(11)°, confirming the anomalous tendency of the methylene units to favor gauche conformers when a short aliphatic segment is placed between two carbonyl groups. Spanish Ministry of Science and Innovation/CTQ2011-22923 Spanish Ministry of Science and Innovation/CGL2011-22441

Hydrazine complexes [Ru(η5-C5H5)(RNHNH2)(PPh3){P(OMe)3}]BPh4 (1–3) and [Ru(η5-C9H7)(RNHNH2) (PPh3){P(OEt)3}]BPh4 (4–6) (R = H, Me, Ph) were prepared by allowing chloro-compounds RuCl(η5-C5H5) (PPh3)[P(OMe)3] and RuCl(η5-C9H7) (PPh3)[P(OEt)3] to react with an excess of hydrazine in refluxing ethanol. Treatment of complexes 1–6 with Pb(OAc)4 at −40 °C yielded diazene derivatives [Ru(η5-C5H5)(RN NH) (PPh3){P(OMe)3}]BPh4 (7, 8) and [Ru(η5-C9H7) (RN NH)(PPh3){P(OEt)3}]BPh4 (10, 11) (R = Me, Ph). Aryldiazene complexes [Ru(η5-C5H5)(RN NH)(PPh3){P(OMe)3}]BPh4 (8, 9) (R = Ph, p-tolyl) were also prepared by allowing hydride RuH(η5-C5H5)(PPh3)[P(OMe)3] to react with aryldiazonium salts [RN2]+BF4– in CH2Cl2. The complexes were characterised by spectroscopy (IR, 1H, 31P NMR) and X-ray crystal structure determination of [Ru(η5-C9H7)(PhNHNH2)(PPh3){P(OEt)3}]BPh4 (6).

International audience; The synthesis and structural characterization, both in solution by means of H-1 and P-31 NMR and UV-vis spectroscopies and in the solid state by X-ray diffraction on single crystal, of a series of gallium(III) and indium(III) meso-mono(diethoxyphosphoryl)porphyrins bearing different peripheral substituents as well as the corresponding monoesters and phosphonic acids are reported. This work describes the first example of the X-ray structure of a self-assembled dimer formed via strong binding between the oxygen atom of the phosphonate substituent and the gallium(III) cations of adjacent porphyrin molecules [Ga-O = 1.9708(13) angstrom].

The occupied and unoccupied electronic structures of three high spin TM(acac) 3 (TM = Cr, Mn, and Fe) complexes (I, II, and III, respectively) were studied by revisiting their literature vapour- phase He(I) and, when available, He(II) photoemission (PE) spectra and by means of original near- edge X- ray absorption fine structure (NEXAFS) spectroscopic data recorded at the OK-edge (OK-edge) and TM (L2,3)- edges (TML2,3- edges). The assignments of the vapour-phase He(I)/He(II) PE spectra were guided by the results of spin- unrestricted non- relativistic Slater transition state calculations, while the OK- edge and TM(L2,3)edge spectroscopic pieces of evidence were analysed by exploiting the results of spin-unrestricted scalar-relativistic time-dependent density functional theory (DFT) and DFT/ROCIS calculations, respectively. Although the actual symmetry (D-3, in the absence of any Jahn-Teller distortion) of the title molecules allowed an extensive mixing between TM t(2g)- like and eg- like atomic orbitals, the use of the Nalewajski- Mrozek TM-O bond multiplicity index combined with a thorough analysis of the ground state (GS) outcomes allowed the assessment of the TM-O bond weakening associated with the progressive TM 3d- based e(g)- like orbital filling. The experimental information provided by K-O- edge spectra was rather poor; nevertheless, the combined use of symmetry, orbitals and spectra allowed us (i) to rationalise minor differences characterizing spectral features along the series, (ii) to quantify the contribution provided by the ligand-to-metal-charge-transfer (LMCT) excitations to the different spectral features, and (iii) to recognize the t2g-/eg- like nature of the TM 3d- based orbitals involved in LMCT transitions. As far as the TML2,3- edge spectra and the DFT/ROCIS results were concerned, the lowest lying L-I, II(3) spectral features included states having either the GS spin multiplicity (S(I) = 3/2, S(II) = 2) or, at higher excitation energies (EEs), states with Delta S = +/- 1. In contrast to that, only states with Delta S = 0, -1 significantly contributed to the IIIL3 spectral pattern. Along the whole series, the L-3 higher EE side was systematically characterized by states involving (TM)2p pi(4) MLCT excitations; as such, coupled- single excitations with DS = 0 were involved in I and II, while single MLCT (TM)2p pi(4) transitions with Delta S = -1 were involved in III.

The O-O-N-N-O-type pentadentate ligands H(3)1,3-pd3a and H(3)1,3-pd2ap (H(3)1,3-pd3a stands for 1,3-propanediamine-N,N,N'-triacetic acid; H(3)1,3-pd2ap stands for 1,3-propanediamine-N,N'-diacetic-N-3-propionic acid) and the corresponding novel octahedral nickel(II) complexes have been prepared and characterized. H(3)1,3-pd3a and H(3)1,3-pd2ap ligands coordinate to nickel(II) ion via five donor atoms (three deprotonated carboxylate atoms and two amine nitrogens) affording octahedral geometry in case of all investigated Ni(II) complexes. A sixth place within octahedra has been occupied by the molecule of water. A six coordinate, octahedral geometry has been established crystallographically for the K[Ni(1,3-pd3a)(H2O)]center dot 3H(2)O complex. Structural data correlating similar chelate Ni(II) complexes have been used for an extensive strain analysis. This is discussed in relation to information obtained for similar complexes. The infra-red and electronic absorption spectra of the complexes are interpreted and compared with related complexes of known geometries. Density functional theory (DFT) has been used to model the most stable geometry isomer and Natural Energy Decomposition Analysis (NEDA) to reveal the energetic relationship of these compounds. The results from density functional studies have been compared with X-ray data. NEDA has been done for the [LNi] and [H2O] units. (C) 2013 Elsevier B.V. All rights reserved.

The O-O-N-N-O-type pentadentate ligands H(3)ed3a, H(3)1,2-pd3a, H(3)eda2p and H(3)ed3p (H(3)ed3a stands for ethylenediamine-N,N,N'-triacetic acid; H(3)1,2-pd3a stands for 1,2-propanediamine-N,N,N'-triacetic acid; H(3)eda2p stands for ethylenediamine-N-acetato-N,N'-di-3-propionic acid and H(3)ed3p stands for ethylenediamine-N,N,N'-tri-3-propionic acid) and the corresponding novel octahedral nickel(II) complexes have been prepared and characterized. H(3)ed3a, H(3)1,2-pd3a, H(3)eda2p and H(3)ed3p ligands coordinate to nickel(II) ion via five donor atoms (three deprotonated carboxylate atoms and two amine nitrogens) affording octahedral geometry in case of all investigated Ni(II) complexes. A sixth place within octahedra has been occupied by the molecule of water. A six coordinate, octahedral geometry has been established crystallographicaly for the [Ni(H2O)(6)][Ni(ed3a)(H2O)](2)center dot 2H(2)O complex. Structural data correlating similar chelate Ni(II) complexes have been used to carry out an extensive configuration analysis. This is discussed in relation to information obtained for similar complexes. The infra-red and electronic absorption spectra of the complexes are discussed in comparison with related complexes of known geometries. Molecular mechanics and density functional theory (DFT) have been used to model the most stable geometric isomer yielding, at the same time, significant structural data. The results from density functional studies have been compared with X-ray data. Natural Energetic Decomposition Analysis (NEDA) has been done for the LNi center dot center dot center dot OH2 unit. (C) 2012 Elsevier Ltd. All rights reserved.

In this work, the quantitative structure–property relationship (QSPR) strategy is applied to predict the normal boiling point (NBP) of pure chemical compounds. In order to propose a comprehensive, reliable, and predictive model, a large dataset of 17,768 pure chemical compounds was exploited. The sequential search mathematical method has been observed to be the only viable search method capable for selection of appropriate model parameters (molecular descriptors) with regard to a data set as large as is used in this study. To develop the model, a three-layer feed forward artificial neural network has been optimized using the Levenberg–Marquardt (LM) optimization strategy. Using this dedicated strategy, satisfactory results were obtained and are quantified by the following statistical parameters: average absolute relative deviations of the predicted properties from existing literature values: 3.2%, and squared correlation coefficient: 0.94.

International audience; The dinuclear Ni-II complex [Ni-2(L-2)][ClO4](2) (3) supported by the 28-membered hexaaza-dithiophenolate macro-cycle (L-2)(2-) binds the N-3(-) ion specifically end-on yielding [Ni-2(L-2)(mu(1,1)-N-3)] [ClO4] (7) or [Ni-2(L-2)(mu(1,1)-N-3)][BPh4] (8), while the previously reported complex [Ni2L1(mu(1,3)-N-3)][ClO4] (2) of the 24-membered macrocycle (L-1)(2-) coordinates it in the end-to-end fashion. A comparison of the X-ray structures of 2, 3, and 7 reveals the form-selective binding of complex 3 to be a consequence of its preorganized, channel-like binding pocket, which accommodates the azide anion via repulsive CH center dot center dot center dot pi interactions in the end-on mode. In contrast to [Ni2L1(mu(1,3)-N-3)] [ClO4] (2), which features a S = 0 ground state, [Ni-2(L-2)(mu(1,1)-N-3)][BPh4] (8) has a S = 2 ground state that is attained by competing antiferromagnetic and ferromagnetic exchange interactions via the thiolato and azido bridges with a value for the magnetic exchange coupling constant J of 13 cm(-1) (H = -2JS(1)S(2)). These results are further substantiated by density functional theory calculations. The stability of the azido-bridged complex determined by isothermal titration calorimetry in MeCN/MeOH 1/1 v/v (log K-11 = 4.88(4) at I = 0.1 M) lies in between those of the fluorido- (log K-11 = 6.84(7)) and chlorido-bridged complexes (log K-11 = 3.52(5)). These values were found to compare favorably well with the equilibrium constants derived at lower ionic strength (I = 0.01 M) by absorption spectrophotometry (log K-11 = 5.20(1), 7.77(9), and 4.13(3) for N-3(-), F-, and Cl- respectively).

The 1:1 molar reactions of NbOX3 with SnBu3H, in toluene at 0 °C in the presence of oxygen/nitrogen donors, resulted in the formation of NbOX2L2 (X = Cl, L2 = dme, 2a; X = Br, L2 = dme, 2b; X = Cl, L = thf, 2c; X = Cl, L = NCMe, 2d; dme = 1,2-dimethoxyethane, thf = tetrahydrofuran), in good yields. The 1:2 reactions of freshly prepared 2d and 2b with the bulky NHC ligands 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene, Imes, and 1,3-bis(2,6-dimethylphenyl)imidazol-2-ylidene, Ixyl, respectively, afforded the complexes NbOCl2(Imes)2, 3, and NbOBr2(Ixyl)2, 4, in 50-60% yields. The reactions of 2b with NaOR, in tetrahydrofuran, gave NbOCl(OR) (R = Ph, 5; R = Me, 6) in about 60% yields. All the products were characterized by analytical and spectroscopic techniques; moreover DFT calculations were carried out in order to shed light on synthetic and structural features. Compounds 3 and 4, whose molecular structures have been ascertained by X-ray diffraction, represent very rare examples of crystallographically characterized niobium-NHC systems.

The cationic tantalum complex {[eta(6)-Ar-CMe2-eta(5)-C5H4]TaPr}[B(C6F5)(4)] (1; Ar = 3,5-Me2C6H3) serves as a starting material for a series of neutral, monocationic, and dicationic derivatives. The cationic hydride {[eta(6)-Ar-CMe2-eta(5)-C5H4]TaH}[B(C6F5)(4)] (2) that results from hydrogenolysis of 1 inserts the di- and trisubstituted olefins cyclopentene and 2-methyl-2-pentene; it reacts with styrene to give the 2,1-insertion product, for which the Ta-CH(Me)Ph group is bound in a sigma(3)-allylic fashion. A neutral complex is obtained from 1 by reaction with Br-, and a dicationic derivative is available by hydride abstraction from 2 using the Lewis acidic trityl cation. All compounds described here retain the unusual ansa-(eta(5)-cyclopentradienyl,eta(6)-arene) coordination mode of the ligand that stabilizes the formally Ta(III) center. X-ray structures and DFT calculations show that the metal-arene interaction contains a significant pi back-donation component (arene

Cocaine is an amphiphilic drug which has the ability to cross the blood–brain barrier (BBB). Here, a combination of neutron diffraction and computation has been used to investigate the atomic scale structure of cocaine in aqueous solutions. Both the observed conformation and hydration of cocaine appear to contribute to its ability to cross hydrophobic layers afforded by the BBB, as the average conformation yields a structure which might allow cocaine to shield its hydrophilic regions from a lipophilic environment. Specifically, the carbonyl oxygens and amine group on cocaine, on average, form ~5 bonds with the water molecules in the surrounding solvent, and the top 30% of water molecules within 4 Å of cocaine are localized in the cavity formed by an internal hydrogen bond within the cocaine molecule. This water mediated internal hydrogen bonding suggests a mechanism of interaction between cocaine and the BBB that negates the need for deprotonation prior to interaction with the lipophilic portions of this barrier. This finding also has important implications for understanding how neurologically active molecules are able to interact with both the blood stream and BBB and emphasizes the use of structural measurements in solution in order to understand important biological function.

The reaction of 1-(2-hydroxyethyl)-3,5-dimethylpyrazole (HL) with anhydrous metal(III) halides (M = Al, Ga, In and Cr) results in the isolation of four novel dinuclear complexes [Al(mu-L)Cl(2)](2) (1), [Ga(mu-L)Cl(2)](2) (2), [In(mu-L)Br(2)(H(2)O)](2)center dot 2thf (3) and [Cr(mu-L)Cl(2)(H(2)O)](2)center dot 1.5thf (4) in good yields. The new complexes have been characterized with the aid of analytical and spectroscopic studies. A single crystal X-ray structure determination in each case confirms the dimeric structure for all the complexes in the solid-state. The pyrazole ethanol ligand binds to the metal through both pyrazole nitrogen and bridging alkoxide oxygen terminals with the formation of a central M(2)O(2) core involving the ethoxide anion. The metal(III) center is pentacoordinated in compounds 1 and 2, while it is hexacoordinated in compounds 3 and 4. (C) 2011 Elsevier B. V. All rights reserved.

A series of allylpalladium dimers having metals connected by binucleating dialkyldithiooxamidate [N(R)SC-CS(R)N](2-) [R = methyl, ethyl, isopropyl, benzyl, isoamyl, (S)-1-(1-phenyl)ethyl, meso-(1-phenyl)ethyl, and rac-(1-phenyl)ethyl] were prepared by reacting the monochelate [(eta(3)-allyl)Pd(N(R)SC-CS(R)NH kappa-S,S Pd)] with [(eta(3)-allyl)PdCl](2) in chloroform. At low temperature (20 degrees C), the bimetallic complexes [(eta(3)-allyl)Pd](2)(mu-dialkyldithiooxamidate kappa-N,N' Pd, kappa-S,S' Pd') (kinetic compounds) are formed in a short reaction time (10 min). At a higher temperature (50 degrees C) and a longer reaction time (24 h), the corresponding bimetallic isomers [(eta(3)-allyl)Pd](2)(mu-dialkyldithiooxamidate kappa-N,S Pd, kappa-N',S' Pd') (thermodynamic compounds) are obtained. Both kinetic and thermodynamic compounds can exist as endo or exo isomers, depending on the reciprocal orientation of the allyl cuspids. Both endo and exo isomers are only detectable in solution when the alkyl substituents are chiral alkyl groups. Moreover, diffractometric modeling agrees with the presence of both isomers in the solid state even when the alkyl substituent is an achiral alkyl group. In a chloroform solution, endo and exo isomers undergo isomeric conversion owing to the apparent allyl rotation that follows the Pd-N bond rupture in the (eta(3)-allyl)Pd(N(Lambda)N) frame of kinetic compounds or in the (eta(3)-allyl)Pd(N(Lambda)S) frame of thermodynamic compounds. The dithiooxamidate [N(R)SC-CS(R)N](2-), when engaged in a kappa-N,S Pd, kappa-N',S'Pd' coordination mode, behaves as a hybrid hemilabile binucleating ligand. At room temperature and in a chloroform solution, the kinetic compounds rearrange into the thermodynamically more stable isomers in about 3 or 4 days. The higher stability of the thermodynamic species was evaluated by means of computational studies in accordance with the maximum hardness principle. Finally, the crystal structures of [(eta(3)-allyl)Pd](2)(mu-diethyldithiooxamidate, kappa-N,S Pd, kappa-N',S' Pd'), [(eta(3)-allyl)Pd](2)(mu-meso-(1-phenyl)ethyldithiooxamidate kappa-N, S Pd, kappa-N',S' Pd'), and [(eta(3)-allyl)Pd](2)(mu-rac-(1-phenyl)ethyldithiooxamidate kappa-N,N' Pd, kappa-S,S' Pd') are reported.

The reactivity of bulky tris(trimethylsilyl) methyl group substituted aluminum trialkyl [(Me(3)Si)(3)CAlMe(2)center dot THF] (1) with a series of substituted benzoic acid derivatives has been investigated. An equimolar reaction of 4-methyl benzoic acid or 4-tert-butyl benzoic acid with 1 in toluene at 50 degrees C leads to the formation of cyclic dimeric aluminum carboxylates [(Me(3)Si)(3)CAl(Me)(mu-O(2)CC(6)H(4)R)](2) (R = Me 2; (t)Bu 3). Reaction of 3,5-di-iso- propylsalicylic acid (H(2)dipsa) with 1 leads to the exclusive isolation of a trimeric organoaluminum carboxylate [(Me(3)Si)(3)CAl(mu-ipsa)](3) (4), in which each aluminum is bound to two carboxylates, a phenoxide, and an alkyl group and produce a 12-membered macrocycle. Deliberate, but controlled, introduction of water in the form of 3,5-di-tert-butyl salicylic acid monohydrate (H(2)dtbsa center dot H(2)O) in the reaction with 1 in toluene leads to the isolation of carboxylate [(Me(3)Si)(3)CAl(mu-O)(mu-Hdtbsa)}(2)] (5) with a bicyclic structure. Compound 5 represents a rare example of an organoalumoxane carboxylate that simultaneously possesses alkyl, oxo, and carboxylate moieties on aluminum. (C) 2011 Elsevier B.V. All rights reserved.

The formation of an aryltellurenyl hydroxide analogue proposed in the telluroxide elimination reaction has been studied. The reaction of the monotelluride dimethyl 5-tert-butyl-2-(butyltellanyl)isophthalate (6) with H(2)O(2) afforded the corresponding aryldiacyloxy-n-butyltellurane (8). The reaction of 6 with oxygen in the presence of moisture resulted in the formation of 8 as the major product along with traces of dimethyl 5-tert-butyl-2-(butyltellurinyl)isophthalate (7) and methyl 5-tert-butyl-3-oxo-3H-benzo[c][1,2]oxa tellurole-7-carboxylate (9). The telluroxide intermediate 7 readily undergoes a facile elimination reaction to give the elusive aryltellurenyl hydroxide, which is immediately trapped by the adjacent methyl ester functionality to give the cyclic tellurenate ester 9. Similarly, the hydrolysis of 7 with H(2)O affords the corresponding dihydroxytellurane 10, which is immediately converted to tellurane 8. Both compounds 8 and 9 have been characterized by single-crystal X-ray crystallographic studies.

Nitrosyl complexes with {Ru-NO}(6) (4(ClO(4))(3)) and {Ru-NO}(7) (4(ClO(4))(2)) configurations have been isolated in the selective molecular framework of [Ru(tpm)(pap)(NO)](n+) (tpm = tris(1-pyrazolyl) methane and pap = 2-phenylazopyridine). The DFT optimized structures of [Ru(II)(tpm)(pap)(NO(+))](3+) (4(3+)) and [Ru(II)(tpm)(pap)(NO(center dot))](2+) (4(2+)) predict that the Ru-N-O groups in the complexes are in almost linear and bent geometries, respectively. In agreement with largely NO centered reduction a sizeable shift in m(NO) frequency of 324 cm (1) has been observed on moving from {Ru(II)-NO(+)} state in 4(3+) to {Ru(II)-NO(center dot)) state in 4(2+). The DFT proposed NO centered spin in {Ru(II)-NO(center dot)) (4(2+)) (Mulliken spin-densities: 0.860 (NO) and 0.087 (Ru)) has been evidenced by its free radical EPR spectrum with g = 1.989. The strongly electrophilic {Ru(II)-NO(+)} state in 4(3+) (m(NO): 1962 cm (1)) can be transformed to the corresponding {Ru(II)-NO(2) } complex (3(+)) in the presence of nucleophile, OH with k = 2.03 x 10 (1) M (1) s (1) at 298 K in CH(3)CN. On irradiation with light the acetonitrile solution of [Ru(II)(tpm)(pap)(NO(+))](3+) (4(3+)) undergoes facile photorelease of NO (k(NO), s (1) = 0.1 x 10 (1) and t(1/2), s = 69.3) with the concomitant formation of the solvate [Ru(II)(tpm)(pap)(CH(3)CN)](2+) (2(2+)). The photoreleased NO can be trapped as an Mb-NO adduct. (C) 2011 Elsevier B.V. All rights reserved.

This review summarizes the rapid developments in the chemistry of phosphonium-stabilized group 1 and 2 methandiides, i.e. that of alkali and alkaline-earth metal bis(iminophosphorane)methandiide and bis(thiophosphorane)methandiide complexes. Apart from syntheses, structures and reactivities, also a critical discussion on bonding is given. The group 2 complexes of this type can truly be seen as polar metal carbene compounds with a formally polar double metal-carbon bond. (C) 2010 Elsevier B.V. All rights reserved.

Four new symmetric mixed-chelate dinuclear complexes type [Cu2(L)2(TAE)]X2, where TAE = tetraacetylethane; L = N,N-dimethyl-N′-benzylethylenediamine (L1) or N,N′-dibenylethylenediamine (L2); X = ClO4 or BPh4 have been synthesized and characterized on the bases of elemental analysis, spectroscopic and conductance measurements. The X-ray crystal analysis of [Cu2(L1)2(TAE)](ClO4)2 demonstrated that the two copper(II) ions are not equivalent. The axial position of the first copper is occupied by a ClO4− ion with a square pyramidal geometry whereas; the second copper ion resides in an octahedral environment determined by two perchlorate anions. However, in solution, the perchlorate ions are driven out by solvent molecules leading to their solvatochromism. The solvatochromism of the complexes were investigated in various organic solvents and also were compared with those of the corresponding mononuclear complexes [Cu(L)(acac)]ClO4. Their solvatochromism were also investigated with different solvent parameters models using stepwise multiple linear regression (SMLR) method. The results suggested that the DN parameter of the solvent has the dominate contribution to the shift of the d–d absorption band of the complexes. The results demonstrated that the complexes with counter ions of BPh4 are more solvatochromic in very weak donor solvents owing to their disinclination in ion-pair formation.

In this contribution, we describe the preparation and single-crystal X-ray diffraction of a new building block for bimetallic solid state materials. X-ray diffraction data of these complexes indicate that (PPh4)(2)[Fe(CN)(5)imidazole]center dot 2H(2)O crystallizes in the triclinic space group P (1) over bar with a = 9.8108(15) angstrom, b = 11.1655(17) angstrom, c = 23.848(4) angstrom, alpha = 87.219(2)degrees, beta = 85.573(2)degrees, gamma = 70.729(2)degrees, and Z = 2, while its precursor Na-3[Fe(CN)(5)(en)]center dot 5H(2)O crystallizes in the monoclinic space group P2(1)/n with a = 8.3607(7) angstrom, b = 11.1624(9) angstrom, c = 17.4233(14) angstrom, beta = 90.1293(9)degrees, and Z = 4. Spectroscopic and magnetic properties of a series of bimetallic materials were obtained by reaction of the complex [Fe(CN)(5)imidazole](2-) with hydrated transition metal ions [M(H2O)(n)](2+) (M = Mn, Co, Zn; n = 4 or 6). The new bimetallic materials obtained are [Co(H2O)(2)][Fe(CN)(5)imidazole]center dot 2H(2)O (1), [Mn(CH3OH)(2)][Fe(CN)(5)imidazole] (2), Zn[Fe(CN)(5)imidazole]center dot H2O (3), and [Mn(bpy)][Fe(CN)(5)imidazole]center dot H2O (4). All of the complexes crystallize in the orthorhombic system. X-ray single-crystal analysis of the compounds identified the Imma space group with a = 7.3558(10) angstrom, b = 14.627(2) angstrom, c = 14.909(2) angstrom, and Z = 4 for 1; the P2(1)2(1)2(1) space group with a = 7.385(5) angstrom, b = 13.767(9) angstrom, c = 14.895(10) angstrom, and Z = 4 for 2; the Pnma space group with a = 13.783(2) angstrom, b = 7.167(11) angstrom, c = 12.599(2) angstrom, and Z = 4 for 3; and the Pnma space group with a = 13.192(3) angstrom, b = 7.224(16) angstrom, c = 22.294(5) angstrom, and Z = 4 for 4. The structures of 1, 2, and 4 consist of two-dimensional network layers containing, as the repeating unit, a cyclic tetramer [M2Fe2(CN)(4)] (M = Mn, Co). H bonding between the layers in the structure of 1 results in a quasi-three-dimensional network. The structure of 3 was found to be three-dimensional, where all of the cyano ligands are involved in bridging between the metal centers. The bridging character of the cyano is confirmed spectroscopically. The magnetic properties have been investigated for all of the bimetallic systems. Compound 1 shows ferromagnetic behavior with an ordering temperature at 25 K, which is higher than the corresponding Prussian Blue analogue Co-x[Fe(CN)(6)]y center dot zH(2)O. Compound 2 shows weak ferromagnetic behavior and an interlayer antiferromagnetic character, while 3, as expected, shows paramagnetic character due to the diamagnetic character of Zn2+. Compound 4 shows antiferromagnetic behavior.

The dinuclear dichloro complexes [(η6-arene)2Ru2(μ-Cl)2Cl2] and [(η5-C5Me5)2M2 (μ-Cl)2Cl2] react with 2-(pyridine-2-yl)thiazole (pyTz) to afford the cationic complexes [(η6-arene)Ru(pyTz)Cl]+ (arene = C6H61, p-iPrC6H4Me 2 or C6Me63) and [(η5-C5Me5)M(pyTz)Cl]+ (M = Rh 4 or Ir 5), isolated as the chloride salts. The reaction of 2 and 3 with SnCl2 leads to the dinuclear heterometallic trichlorostannyl derivatives [(η6-p-iPrC6H4Me)Ru(pyTz)(SnCl3)]+ (6) and [(η6-C6Me6)Ru(pyTz)(SnCl3)]+ (7), respectively, also isolated as the chloride salts. The molecular structures of 4, 5 and 7 have been established by single-crystal X-ray structure analyses of the corresponding hexafluorophosphate salts. The in vitro anticancer activities of the metal complexes on human ovarian cancer cell lines A2780 and A2780cisR (cisplatin-resistant), as well as their interactions with plasmid DNA and the model protein ubiquitin, have been investigated.

Eight new antimony(III) iodide complexes of the heterocyclic thioamides, 2-mercapto-1-methylimidazole (MMI), 2-mercaptobenzimidazole (MBZIM), 5-ethoxy-2-mercaptobenzimidazole (EtMBZIM), 2-mercaptothiazolidine (MTZD), 3-methyl-2-mercaptobenzothiazole (NMeMBZT), 2-mercapto-3,4,5,6-tetrahydropyrimidine (tHPMT), 2-mercaptopyridine (PYT), and 2-mercaptopyrimidine (PMT) of formulas {[SbI(3)(MMI)(2)].MeOH} (1), [SbI(3)(MBZIM)(2)] (2), {[SbI(2)(mu(2)-I)(EtMBZIM)(2)](2).H(2)O} (3), [SbI(3)(MTZD)] (4), [(NMeMBZT)SbI(2)(mu(2)-I)(2)(mu(2)-S-NMeMBZT)SbI(2) (NMeMBZT)] (5), {[SbI(3)(tHPMT)(3)].MeOH} (6), [SbI(3)(PYT)] (7), and [SbI(3)(PMT)(2)] (8), have been synthesized and characterized by elemental analysis, FT-IR spectroscopy, FT-Raman spectroscopy, and TG-DTA analysis. The crystal structures of 3, 4, 5, 6, and 7 were also determined by X-ray diffraction. The complexes show interesting structural motifs. Complex 6 is a monomer, with octahedral (Oh) geometry around the metal ion formed by three sulfur and three iodide atoms. Complexes 3 and 5 are dimers, with a square pyramidal (SP) geometry in each monomeric unit, while complexes 4 and 7 are polymers with pseudotrigonal bipyramidal (psi-TBP). Two or three sulfur atoms from thioamide ligands and three iodide atoms are bound to Sb atoms forming building blocks for the dimers and polymers. Strong intramolecular interactions between mu(2)-I and/or mu(2)-S and Sb atoms stabilize both structures. In dimer complex 5, two terminal iodide and one terminal sulfur atom are bonded to the Sb ion, while two mu(2)-I and one mu(2)-S bridging atoms bridge the metal ions forming psi-Oh geometry. Computational studies using multivariant linear regression (MLR) and artificial neural networks (ANN) and considering biological results (50% inhibitory concentration, IC(50)) as dependent variables derived a theoretical equation for IC(50) values of the complexes studied. The calculated IC(50) values are compared satisfactorily with the experimental inhibitory activity of the complexes measured. Complexes 3-7 were used to study their influence upon the catalytic peroxidation of linoleic acid by the enzyme Lipoxygenase (LOX). Compounds 1-8 were also tested for in vitro cytotoxicity, and they showed mostly a moderate cytostatic activity against a variety of tumor cell lines but comparable with those found for the antimony(III) chloride and bromide complexes, reported earlier [Ozturk et al. Inorg. Chem. 2007, 46, 2861-2866; Ozturk et al. Inorg. Chem. 2009, 48, 2233-2245]. ispartof: Inorganic Chemistry vol:49 issue:2 pages:488-501 ispartof: location:United States status: published

Treatment of (eta(5)-C(5)H(4)C(2)H(4)NR)V(N-t-Bu)Me (R = Me, i-Pr) and CpV(N-p-Tol)(N-i-Pr(2))Me (Cp = eta(5)-C(5)H(5)) with B(C(6)F(5))(3) or [Ph(3)C][B(C(6)F(5))(4)] results in formation of the corresponding cations, [(eta(5)-C(5)H(4)C(2)H(4)NR)V(N-t-Bu)](+) and [CpV(N-p-Tol)(N-i-Pr(2))](+). The latter could also be generated as its N,N-dimethylaniline adduct by treatment of the methyl complex with [PhNMe(2)H][BAr(4)] (Ar = Ph, C(6)F(5)). Instead, the analogous reaction with the linked Cp-amido precursor results in protonation of the imido-nitrogen atom. Sequential cyclometalation of the amide substituents gave cationic imine complexes [(eta(5)-C(5)H(4)C(2)H(4)NCR'(2))V(NH-t-Bu)](+) (R'= H, Me) and methane. Reaction of cationic [(eta(5)-C(5)H(4)C(2)H(4)NR)V(N-t-Bu)](+) with olefins affords the corresponding olefin adducts, whereas treatment with 1 or 2 equiv of 2-butyne results in insertion of the alkyne into the vanadium-nitrogen single bond, affording the mono- and bis-insertion products [(eta(5)-C(5)H(4)C(2)H(4)N(i-Pr)C(2)Me(2))V(N-t-Bu)](+) and [(eta(5)-C(5)H(4)C(2)H(4)N(i-Pr)C(4)Me(4))V(N-t-Bu)](+). The same reaction with the half-sandwich compound [CpV(N-p-Tol)(N-i-Pr(2))](+) results in a paramagnetic compound that, upon alcoholysis, affords sec-butylidene-p-tolylamine, suggesting an initial [2+2] cycloaddition reaction. The difference in reactivity between the V-N bond versus the V=N bond was further studied using computational methods. Results were compared to the isoelectronic titanium system CpTi(NH)(NH(2)). These studies indicate that the kinetic product in each system is derived from a [2+2] cycloaddition reaction. For titanium, this was found as the thermodynamic product as well, whereas the insertion reaction was found to be thermodynamically more favorable in the case of vanadium.

We have recorded room temperature OH stretching overtone spectra of benzyl alcohol in the second and third overtone regions and jet-cooled OH stretching spectra in the fundamental and third overtone region. The spectra were recorded using photoacoustic and nonresonant ionization techniques, respectively. The spectra are characterized by a single band for each OH stretching overtone region suggesting the existence of one dominant stable conformer. In addition, our mass selected resonance enhanced multi photon ionization spectrum shows only one origin band. Ab initio calculations for benzyl alcohol yielded a lowest energy conformer adopting a gauche cis conformation around the alcoholic group, which is supported by our calculated OH stretching intensities.

The tricoordinated cationic Cu-I complex [Cu(kappa(2)-P,P'-DPEphos)(kappa(1)-P-DPEphos)][BF4] (1) (DPEphos = bis(2-(diphenylphosphino)phenyl) ether) containing a dangling phosphorus center was synthesized from the reaction of [Cu(CH3CN)(4)][BF4] with DPEphos in a 1:2 molar ratio in dichloromethane. When complex 1 is treated with MnO2, elemental sulfur, or selenium, the uncoordinated phosphorus atom undergoes oxidation to form a PE bond resulting in the formation of complexes of the type [Cu(kappa(2)-P,P'-DPEphos)(kappa(2)-P,E-DPEphos-E)][BF4] (2, E = O; 3, E = S; 4, E = Se) containing a Cu-E bond. The zigzag polymeric Cu-I complex [Cu(kappa(2)-P,P'-DPEphos)(mu-4,4'-bpy)](n)[BF4](n) (5) was prepared by the reaction of [Cu(CH3CN)(4)][BF4] with DPEphos and 4,4'-bipyridine in an equimolar ratio. The stereochemical influences of DPEphos on its coordination behavior are examined by density functional theory calculations.

The O-O-N-N-O-type pentadentate ligands H(3)ed3a, H(3)pd3a and H(3)pd3p (H(3)ed3a stands ethylenediamine-N,N,N'-triacetic acid; H3pd3a stands 1,3-propanediamine-N,N,N'-triacetic acid and H3pd3p stands 1,3-propanediamine-N,N,N'-tri-3-propionic acid) and the corresponding novel octahedral or square-planar/trigonal-bipyramidal copper(II) complexes have been prepared and characterized. H(3)ed3a, H(3)pd3a and H(3)pd3p ligands coordinate to copper(II) ion via five donor atoms (three deprotonated carboxylate atoms and two amine nitrogens) affording octahedral in case of ed3a(3-) and intermediate square-pyramidal/trigonal-bipyramidal structure in case of pd3a(3-) and pd3p(3-). A six coordinate, octahedral geometry has been established crystallographically for the [Mg(H2O)(6)][Cu(ed3a) (H2O)](2) center dot 2H(2)O complex and five coordinate square-pyramidal for the [Mg(H2O)(5)Cu(pd3a)][Cu(pd3a)] center dot 2H(2)O. Structural data correlating similar chelate Cu(II) complexes have been used for the better understanding the pathway: octahedral -> square-pyramidal trigonal- bipyramid geometry. An extensive configuration analysis is discussed in relation to information obtained for similar complexes. The infra-red and electronic absorption spectra of the complexes are discussed in comparison with related complexes of known geometries. Molecular mechanics and density functional theory (DFT) programs have been used to model the most stable geometric isomer yielding, at the same time, significant structural data. The results from density functional studies have been compared with X-ray data. (c) 2006 Elsevier B.V. All rights reserved.

A series of rare earth metal dialkyl complexes was prepared with the general formula [Me(2)TACN-(B)-NR]M(CH2SiMe3)(2) (TACN = 1,4,7-triazacyclononane, B = (CH2)(2), SiMe2; R = tBu, secBu, nBu; M = Sc, Y, Nd, La). For M = Sc, mixed monoalkyl-monochloro complexes were also accessible. Selected examples of these complexes were structurally characterized and show the metal in a distorted octahedral environment. With Lewis or Bronsted acid activators the dialkyl compounds can be converted to the corresponding monoalkyl cations, which were characterized by NMR spectroscopy. Comparative testing in catalytic ethylene polymerization showed that the catalyst activity is most strongly influenced by the metal ionic radius, but that variations in the ligand backbone and substitution pattern do influence other factors, such as polymer molecular weight and catalyst stability. Catalysts with the intermediately sized rare earth metal yttrium generally showed the highest activity, but some of these catalysts produce polyethylene with broad molecular weight distributions, suggesting multisite behavior. Hypothetically this could be caused by intermolecular ligand scrambling processes. Evidence that these may occur was found in the isolation of the "half-flyover" bimetallic yttrium complex {[eta(3):eta(1)-[Me(2)TACN(CH2)(2)NtBu]Y(CH2SiMe3)}{eta(3):mu-eta(1)-[Me(2)TACN(CH2)(2)NtBu]Y(CH2SiMe3)(3).

The synthesis and characterization of the first examples of two tellurium compounds based on 2-phenyl-5,6-dihydro-4H-1,3-oxazine substrate are described. Intramolecular (TeN)-N-... interaction in [2-(2-phenyl-5,6-dihydro-4H-1,3-oxazinyl)] tellurenyl chloride is established by single X-ray crystallography. (c) 2005

This review seeks to evaluate the role of low oxidation state transition metal clusters (metal carbonyl clusters) in catalysis. The review commences with a discussion of the cluster surface analogy and then proceeds to discuss whether catalysis takes place by intact molecular clusters or mononuclear fragments; both these topic have been fiercely contested in the literature. Next, the application of clusters in organic transformations is briefly reviewed with an emphasis given to reactions that cannot be conducted using other catalysts (or pre-catalysts); areas for future studies are also highlighted. The latest developments in cluster immobilisation using alternative solvents such as water, ionic liquids and supercritical fluids, and the use of clusters as precursors to heterogeneous nanocluster catalysts are reviewed. Finally, the possibility of using materials at the cluster-colloid interface in catalytic: applications is discussed.(C) 2004 Elsevier B.V. All rights reserved.

The chemistry of monocyclopentadienyl titanium complexes with pendant arene groups on the cyclopentadienyl ligand is reviewed, with an emphasis on cationic titanium dialkyl derivatives and their performance in catalytic olefin conversion. In these cationic species, the pendant arene group can coordinate in intramolecular fashion to the metal centre. The effect of this arene coordination on catalytic olefin conversion depends strongly on the nature of the bridge between the cyclopentadienyl and arene moieties. Whereas intramolecular arene coordination is generally detrimental to styrene and propene polymerisation performance, it causes a dramatic switch in ethene conversion behaviour, resulting in high activity and selectivity for catalytic trimerisation of ethene to 1-hexene. Possible reasons for this behaviour are discussed. (C) 2003 Elsevier B.V. All rights reserved.

The reactions of R2Se (3) and R2Te (4) (R = 2-(4,4-dimethyl-2-oxazolinyl)phenyl) with HgCl2 and Pd(COD)Cl-2 are described. The reaction of selenoether 3 with HgCl2 affords the expected complex R2SeHgCl2 (5), which is stable in solution. In contrast, the analogous tellurium complex R2TeHgCl2 (6) undergoes slow dismutation in chlorinated solvents to give the fragments RTeCl (7) and RHgCl (8).

Titanocene neopentyl complexes with one cyclometallated tert-butylcyclopentadienyl group, (eta(5)-C5H4R)(eta(5),eta(1)-C5H4CMe2CH2)Ti(CHCMe3) are readily obtained from the corresponding titanocene dichlorides and bis(neopentyl)magnesium. These compounds lose neopentane by a-H abstraction from the cyclometallated ligand to generate alkylidene species in which the alkylidene moiety is connected to one of the cyclopentadienyl ligands. The alkylidene (C5H4Me)(C5H4CMe2CH)Ti(PMe3) reacts with benzene-d(6) by stereoselective addition of a C-D bond across the Ti=C bond. These 'tucked-in' alkylidene species also exhibit a wide range of reactivity towards unsaturated substrates (alkynes, ethene, benzonitrile), initiated by cycloaddition to the Ti=C bond. (C) 2002 Elsevier Science B.V. All rights reserved.

The mono(cyclopentadienyl-arene)titanium complexes [eta(5)-C(5)H(3)R-(bridge)-Ar]TiCl(3), activated by methylalumoxane (MAO) cocatalyst, form a family of highly active catalysts for the trimerization of ethene, giving 1-hexene as the main product. Concomitant cotrimerization of ethene and 1-hexene, to give mainly 5-methylnon-1-ene, is also observed. The selectivity for trimerization depends on the presence of a pendant arene group on the cyclopentadienyl ligand and the nature of the bridge between these two ligand moieties. In the absence of a pendant arene, polyethene is the main product. The highest activity and selectivity for trimerization was observed for catalysts with a disubstituted C(1) bridge between the cyclopentadienyl and arene ligand moieties. A SiMe(3) substituent on the cyclopentadienyl ligand improves catalyst activity and selectivity, whereas methyl substitution of the arene decreases activity. Nevertheless, combining cyclopentadienyl SiMe(3) substitution with arene Me substitution gives rise to a catalyst with the highest activity and selectivity, evidence of the strongly nonlinear additivity of ligand substituent effects in this system. The cyclopentadienyl-arene ligand is likely to exhibit hemilabile behavior during catalysis, stabilizing intermediates by eta(6) coordination and dissociating or slipping to make room for the incoming substrate. The presence of two pendant arene groups on the cyclopentadienyl ligand diminishes the activity of the catalyst but greatly enhances its stability.

The bis(phosphine), Ph2POCH2CH2N(CH3)PPh2(1) reacts with [Pt(COD)Cl2] to give seven-membered cis-chelated complex 2. The complex was characterized by elemental analysis, IR, and NMR spectroscopic methods of which the 31P{1H} NMR data is very informative and allows the direct measure of the P–P coupling through metal centers otherwise can not be seen in the free ligand as the two phosphorus centers are five-bonds apart. The structure of the platinum(II) complex was determined by X-ray crystallography., © Elsevier

Permethyl yttrocene 2-furyl ate-complexes Cp*2Y(μ-C4H3O)(μ-Cl)Li(THF)2 (1, Cp* = C5-Me5) and Cp*2Y(μ-C4H3O)2Li(TMEDA) (2) were obtained by reaction of Cp*2Y(μ-Cl)2Li(OEt2)2 with 1 and 2 equiv of 2-lithiofuran, respectively. Furan is metalated by (Cp*2YH)2 in hydrocarbon solvents to give the 2-furyl complex Cp*2Y(η2-C4H3O) (3). With Lewis bases, 3 reacts to give the adducts Cp*2Y(η1-C4H3O)(L) (L = THF, 4; pyridine), of which 4 was crystallographically characterized. Compound 3 decomposes through deprotonation and ring-opening of the 2-furyl group to give the (crystallographically characterized) bimetallic ynyl-enolate complex (Cp*2Y)2(μ-OCH=CHC≡C) (5). With excess H2, 3 is transformed into the crystallographically characterized oxo-complex (Cp*2Y)2(μ-O) (6), free furan, and n-butane. In the presence of a large excess of furan, this reaction stops at the enolate species Cp*2YOCH=CHEt.

The authors thank EaStCHEM, the Royal Society (for a Wolfson Merit Award for D.O’H.) and CNPq and FAPESP are also gratefully acknowledged for the studentships (to R.A.C. #2011/01170-1, FAPESP), as is CNPq for the fellowship (R.R.). Intramolecular CF···FC interactions in selected organofluorine compounds (all-syn-1,2,3,4- and all-syn-1,2,4,5-tetrafluorocyclohexane, 1,8-difluoronaphthalene, 4,5-difluorophenanthrene, 2,2′,5,5′-tetrafluorobiphenyl) were studied at the MP2/aug-cc-pVDZ level using the recently developed noncovalent interaction (NCI) method. For the optimized minima, all CF···FC interactions that are identified by this method are classified as attractive, even in those cases where suitable isodesmic reaction energies fail to provide evidence for an energetic stabilization. Possible relations between these interactions and the observable JFF spin–spin coupling constant values are discussed. Postprint

Funding: Engineering and Physical Sciences Research Council (EPSRC) Four related sterically restricted pen-substituted acenaphthenes have been prepared containing mixed tin phosphorus moieties in the proximal 5,6-positions (Acenap[SnR3][(PPr2)-Pr-i]; Acenap = acenaphthene-5,6-diyl; R-3 = Ph-3 (1), Ph2Cl (2), Me2Cl (3), Bu2Cl (4)). The degree of intramolecular P-Sn bonding within the series was investigated by X-ray crystallography, solution and solid-state NMR spectroscopy, and density functional theory (DFT/B3LYP/SBKJC/PCM) calculations. All members of the series adopt a conformation such that the phosphorus lone pair is located directly opposite the tin center, promoting an intramolecular donor acceptor P -> Sn type interaction. The extent of covalent bonding between Sn and P is found to be much greater in triorganotin chlorides 2-4 in comparison with the triphenyl derivative 1. Coordination of a highly electronegative chlorine atom naturally increases the Lewis acidity of the tin center, enhancing the Ip(P)-sigma*(Sn-Y) donor acceptor 3c-4e type interaction, as indicated by conspicuously short Sn-P peri distances and significant (1)J(P-31,Sn-119) spin spin coupling constants (SSCCs) in the range 740-754 Hz. Evidence supporting the presence of this interaction was also found in solid-state NMR spectra of some of the compounds which exhibit an indirect spin spin coupling on the same order of magnitude as observed in solution. DFT calculations confirm the increased covalent bonding between P and Sn in 2-4, with notable WBIs of ca. 0.35 obtained, in comparison to 0.1 in 1. Postprint

The reaction of [MoO2Cl2(pzpy)] (1) (pzpy = 2-[3(5)-pyrazolyl]pyridine) with water in an open reflux system (16 h), in a microwave synthesis system (120 degrees C, 2 h), or in a Teflon-lined stainless steel digestion bomb (100 degrees C, 19 h) gave the molybdenum oxide/pyrazolylpyridine polymeric hybrid material [Mo3O9(pzpy)](n) (2) as a microcrystalline powder in yields of 72-79%. Compound 2 can also be obtained by the hydrothermal reaction of MoO3, pzpy, and H2O at 160 degrees C for 3 d. Secondary products isolated from the reaction solutions included the salt (pzpyH)(2)(MoCl4) (3) (pzpyH = 2-[3(5)-pyrazolyl]pyridinium), containing a very rare example of the tetrahedral MoCl42- anion, and the tetranuclear compound [Mo4O12(pzpy)(4)] (4). Reaction of 2 with excess tert-butylhydroperoxide (TBHP) led to the isolation of the oxodiperoxo complex [MoO(O-2)(2)(pzpy)(4)] (5). Single-crystal X-ray structures of 3 and 5 are described. Fourier transform (FT)-IR and FT Raman spectra for 1, 4, and 5 were assigned based on density functional theory calculations. The structure of 2 was determined from synchrotron powder X-ray diffraction data in combination with other physicochemical information. In 2, a hybrid organic inorganic one-dimensional (1D) polymer, (1)(infinity)[Mo3O9(pzpy)], is formed by the connection of two very distinct components: a double ladder-type inorganic core reminiscent of the crystal structure of MoO3 and 1D chains of corner-sharing distorted {MoO4N2} octahedra. Compound 2 exhibits moderate activity and high selectivity when used as a (pre)catalyst for the epoxidation of cis-cyclooctene with TBHP. Under the reaction conditions used, 2 is poorly soluble and is gradually converted into 5, which is at least partly responsible for the catalytic reaction.

The diazoalkane complexes [Ru(η5-C5H5)(N2CAr1Ar2)(PPh3)(L)]BPh4 (1–5: Ar1 = Ar2 = Ph (a), Ar1 = Ph and Ar2 = p-tolyl (b), Ar1Ar2 = C12H8 (c), Ar1 = Ph and Ar2 = PhCO (d); L = PPh3 (1), P(OMe)3 (2), P(OEt)3 (3), PPh(OEt)2 (4), ButNC (5)) were prepared by allowing the chloro compounds RuCl(η5-C5H5)(PPh3)(L) to react with the diazoalkanes Ar1Ar2CN2 in ethanol. Treatment of complexes 1–5 with ethylene (CH2═CH2) under mild conditions (1 atm, room temperature) led not only to the η2-ethylene complexes [Ru(η5-C5H5)(η2-CH2═CH2)(PPh3)(L)]BPh4 (10–14) but also to dipolar (3 + 2) cycloaddition, affording the 4,5-dihydro-3H-pyrazole derivatives [Ru(η5-C5H5){η1-N═NC(Ar1Ar2)CH2CH2}(PPh3)(L)]BPh4 (6–9). Acrylonitrile (CH2═C(H)CN) reacted with diazoalkane complexes 2 and 3 to give the 1H-pyrazoline derivatives [Ru(η5-C5H5){η1-N═C(CN)CH2C(Ar1Ar2)NH}(PPh3)(L)]BPh4 (19, 20). However, reactions with propylene (CH2═C(H)CH3), maleic anhydride (ma, CH═CHCO(O)CO) and dimethyl maleate (dmm, CH3OCOCH═CHOCOCH3) led to the η2-alkene...

The rotational spectrum of trifluoroacetylacetone shows that the molecule exists in an enolic C-s form and displays the features of internal rotations of the CH3 and CF3 groups, whose barriers to internal rotation were determined to be V-3 = 379 and 30.8 cm(-1), respectively. Its internal dynamics appears to be intermediate between those of acetylacetone, where proton tunneling and low-barrier internal rotation of the two methyl groups make the spectrum quite complex, and hexafluoroacetylacetone, a perfectly "rigid" molecule on the time scale of microwave spectroscopy.

The group 11 metal complexes of two short-bite PNP ligands, C6H5N{P(OC6H3(OMe-o)(C3H5-p))(2)}(2) (1) and C6H5N{P(OC6H4C3H5-o)(2)}(2) (2), are described. Ligands 1 and 2 on treatment with copper(I) halides (CuX, X = Cl, Br, or I) yielded dimeric, tetranuclear complexes of the type [(CuX)(4){C6H5N(PR2)(2)}] (R = OC6H3(OMe-o)(C3H5-p), X = Cl (3), Br (5), 1(7); R = OC6H3(C3H5-o), X = Cl (4), Br (6), I (8)). The chloro-derivative 3 adopts the common "stair-step" geometry, whereas the bromo- and iodo-derivatives form Cu-4 square planes with two tetracoordinating mu(4)-halides capping the axial positions to give octahedral geometry with two other mu(2)-halides being in the plane. The iodo-derivative 8 with a very short Cu-Cu distance of 2.568 angstrom shows photoluminescence in the solid state.

Time-resolved resonance Raman (TR3) spectroscopy has been used to study the structure of the triplet excited state of bromanil. These experimental results were then simulated using parameters from density functional theoretical (DFT) calculations and wave packet dynamics, in order to understand the structure and mode-specific displacements of the resonant excited state. The transition dipole moments and the energy separation of the T1 and Tn states were obtained from time-dependent DFT calculations. We have demonstrated application of the technique to tetrabromo-p-benzoquinone. From our calculations, the observed T1 \rightarrow Tn absorption spectrum has been assigned to the 3Bg \rightarrow 3Bu transition. The geometry has been optimized for the resonant higher triplet state, Tn, and is found to be in good agreement with the predictions of the wave packet dynamical simulations. Mode-specific displacements of the triplet state geometry have been obtained from simulations and these have been rationalized with respect to the molecular orbital involved. Thus, we have demonstrated that from the simulations of the experimental TR3 spectral data, valuable additional information can be derived on the structure of the transient states that may then be used for elucidation of structure-reactivity correlation in the future.