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A number of 2,9-disubstituted 1,10-phenanthrolines are synthesized. These are used as ligands in different cationic (eta3-allyl)palladium and -platinum complexes. It was found that while a syn configuration was by far the most stable one with the parent 1,10-phenanthroline, 2,9-substituents such as methyl, chloro, cyano, and propynyl induced a preference for the anti configuration. Since terminal nucleophilic addition to anti-eta3-allyl complexes will yield (Z)-alkenes, this observation opens up a potentially selective route to (Z)-alkenes. Using molecular mechanics calculations these effects may be rationalized.

Platinum(II) olefin compounds [PtMe(N,N′-imino, amide)(η2-olefin)] have been found to dimerize spontaneously in solution, yielding dinuclear complexes through an oxidative coupling. The extended conjugation within the molecules produces an intense blue color, and the properties of the compounds have been investigated through NMR spectroscopy, optical measurements, and theoretical calculations. The solid-state structure of a representative compound has been solved.

New neutral carbene complexes of gold(I) [Au(Im-Me)X] (X = Cl, Au1; X = Br, Au2; X = I, Au3) have been synthesized and fully characterized by different techniques, including NMR and UV-vis absorption spectroscopy and single crystal X-ray diffraction. The carbene ligand Im-Me is decorated with a glucoside fragment via a triazole linker, obtainable through a click chemistry reaction. The compounds retain the Au-NHC fragment in aqueous solvents, and an equilibrium between the neutral halo- and the cationic di-carbene form [Au(Im-Me)2]+ is observed, whose extent follows the trend Au1 < Au2 < Au3. Cytotoxicity studies on two cancer and two non-tumorigenic cell lines reflect the solution behavior, as a certain difference among the complexes was disclosed, with the iodo complex Au3 being more active and selective. The compounds interact with both DNA and protein model systems. The X-ray structure of the adduct formed upon the reaction of Au1 with bovine pancreatic ribonuclease (RNase A) reveals Au binding at the side chain of His105 of both protein molecules A and B of the asymmetric unit. The binding of gold atoms at both the nitrogen atoms of the imidazole ring of His15 and at the N-terminal tail has been found in the adduct formed with hen egg white lysozyme.

This study describes new platinum(II) cationic five-coordinate complexes (1-R,R’) of the formula [PtR(NHC)(dmphen)(ethene)]CF3SO3 (dmphen = 2,9-dimethyl-1,10-phenanthroline), containing in their axial positions an alkyl group R (methyl or octyl) and an imidazole-based NHC-carbene ligand with a substituent R’ of variable length (methyl or octyl) on one nitrogen atom. The Pt–carbene bond is stable both in DMSO and in aqueous solvents. In DMSO, a gradual substitution of dmphen and ethene is observed, with the formation of a square planar solvated species. Octanol/water partitioning studies have revealed the order of hydrophobicity of the complexes (1-Oct,Me > 1-Oct,Oct > 1-Me,Oct > 1-Me,Me). Their biological activity was investigated against two pairs of cancer and non-cancer cell lines. The tested drugs were internalized in cancer cells and able to activate the apoptotic pathway. The reactivity of 1-Me,Me with DNA and protein model systems was also studied using UV–vis absorption spectroscopy, fluorescence, and X-ray crystallography. The compound binds DNA and interacts in various ways with the model protein lysozyme. Remarkably, structural data revealed that the complex can bind lysozyme via non-covalent interactions, retaining its five-coordinate geometry.

The first aim of the present study is the development of a new ruthenium(III) complex, belonging to NAMI-A class, with a potentially high cytotoxic ability. The presence of a fully protected sugar moiety as ruthenium ligand should increase the complex ability to cross cellular membranes. Furthermore, it sets this molecule in the area of biocompatible agents as tumor drug. The second, more relevant, purpose is to verify the ruthenium complexes activity after loading into liposomes. We reported the characterization and in vitro biological assays of pyridine derivatives of ruthenium complexes loaded into Egg l -α-phosphatidylcholine cholesterol/DSPE-PEG liposomes. Dynamic light scattering estimates that the sizes of all obtained liposomes are in the 100 nm range. This value is suitable for in vivo use. The loading ability and release kinetic allowed selecting the best ratio between the lipid fraction and metal to be tested in cellular experiments. The growth inhibitory effects of both liposomal and free complex in PC-3 prostate cancer cell lines demonstrate a high cytotoxic ability of the liposome entrapped ruthenium (III) complex suggesting additional role further the antimetastatic function.

Novel coordinatively saturated platinum(II) compounds bearing C-linked carbohydrates were synthesized and characterized. The complexes exhibit bipyramidal trigonal geometry with a bidentate nitrogen ligand and ethylene in the equatorial plane. The axial positions are occupied by a halide ligand X and a D-galactose or D-glucose derivative, linked either via C1 or C6. The compounds were designed for evaluation of the biological activity because they combine the steady coordinative saturation, the beneficial action of the modular sugar moiety and the organometallic nature of the Pt-sugar linkage, which is expected to be stable in the biological media, until the target is reached. The newly synthesized molecules were stable in mixed DMSO/aqueous solvents, able to bind DNA in vitro and exhibited a selective cytotoxic activity on cancer cells through apoptosis activation.

This communication describes extremely efficient homogeneous iron(III) catalysts for the synthesis of solketal from glycerol and acetone. The activities are the highest ever reported so far for this type of reaction, with TOFs up to 10 5 h − 1 at negligible catalyst loading.

New Zn-based catalysts are described that act as heterogenized or heterogeneous catalysts, with easy recovery and re-utilization with a limited or even zero Zn-leaching. For stabilizing in the heterogeneous form the catalytically active Zn centre, mixed oxides, ZIF-8 and Zn-tethered systems have been synthesized and found to sensibly reduce the leaching of Zn in solution with respect to ZnO, making possible their recovery and reuse. ZIF-8 can be used for long time of reaction, reaching high DEC yields (comparable or higher than those obtained with ZnO) without any significant loss of zinc.

It is described the simple design of a series of N,N′,O,O′-chiral ligands (elpaN-salen-H2), which represent a subset of the elpaN-type library of ligands based on β-1,2- d -glucodiamine. The corresponding Mn(III) complexes were examined in the asymmetric epoxidation of styrenes with satisfactory results, e.g. cis-β-methylstyrene was functionalised in ees up to 88%.

New zinc(II) compounds containing functionalized Schiff bases have been prepared and characterized. The complexes catalyze the transesterification of soybean oil in mild conditions, and their activity can be modulated by a fine selection of the anions and/or of the substituents on the ancillary bidentate ligand. The compounds are active in the esterification of fatty acids and could therefore also be used to produce biodiesel from waste oils.

The coordinated olefin in dicationic platinum(II) and palladium(II) complexes [M(PNP)(olefin)](SbF6)2 (M = Pt, Pd; PNP = 2,6-bis(diphenylphosphinomethyl)pyridine; olefin = ethene, propene) is electrophilic enough to react with benzene rings activated by methoxy substituents. If the proton released by the aromatic ring is trapped by a base, stable σ-alkyl derivatives of the type [M(PNP)CH2CH(R)Ar](SbF6) or [M(PNP)CH(R)CH2Ar](SbF6) (R = H, Me) are formed; otherwise the M−C σ-bond can be cleaved by the proton, setting up a catalytic cycle that leads to the alkylated aromatic compound. The molecular structure of the σ-alkyl derivative [(PNP)PtCH2CH2−C6H2(OMe)3](BF4) has been determined by X-ray diffraction analysis, and the factors affecting the mechanism and the rates of the catalytic reaction have been qualitatively investigated and rationalized, showing that the rates of C−C bond formation and M−C bond cleavage are inversely correlated.

The simple synthesis of new O,N,O′-tridentate ligands derived from carbohydrates is illustrated. The ligands are obtained by condensing 2-amino-α- d -glucosides or 2-amino-α- d -alloside with several 3,5-disubstituted-2-hydroxybenzaldehydes. The efficiency of the imines in the V(IV)-promoted asymmetric oxidation of thioanisole has been examined and ee's up to 60% have been achieved.

The ability of chiral diamine silver complexes to bind chiral and prochiral alkenes has been analyzed in detail. The stereoselectivity in binding of alkenes to a chiral ethanediamine silver complex has been investigated by NMR. The low-energy conformations of several small model complexes have been explored by DFT methods. By successive substitution of the computational model complexes, it has been possible to elucidate the role of each amine substituent in achieving successful discrimination of alkenes. The conformational space has been fully explored using small model systems, allowing an unbiased calculation of stereoselectivities that match well the experimental results. For a chiral allylic alcohol substrate, the correct stereoselectivity was obtained only when the structures were optimized with a continuum representation of the solvent. The discrepancy between gas phase and solution data is found to result from a competition between internal stabilization and solvation of the OH group of the substrate.

New chiral P,N-chelates o-Ph2PC6H4CHNR (R=carbohydrate residue) derived from d -glucose and d -mannose were described. The synthesis of palladium(0) and rhodium(I) complexes of respective formula [Pd(P,N-chelate)(fumarodinitrile)] and [Rh(1,5-cyclooctadiene)(P,N-chelate)]BF4 was performed. It was found that the ligands effectively discriminate between the enantioface of fumarodinitrile in the Pd(0) species, prompting up to 100% diastereomeric excess when R is a 2,3,4-tri-O-acetylated glucoside moiety linked to N through C6. The catalytic activity of the complexes towards allylic alkylation and olefin hydroboration was also examined.

Complexes of a tertiary diphosphine with cyclic core, cis - P , P ′-diphenyl-1,4-diphospha-cyclohexane (dpdpc), with metal ions of Groups 9 and 10 have been prepared and characterised. In neutral M(0) or M(II) (M=Pt, Pd) complexes the diphosphine acts as a bridge affording polynuclear products. Instead, in cationic mononuclear Pt(II) and Pd(II) species a clear preference for chelation of dpdpc is observed. Also the cation [Ni(dpdpc) 2 Cl] + contains the two dpdpc moieties as chelates. The molecular and crystal structure of [Ni(dpdpc) 2 Cl] 2 (NiCl 4 ) discloses a significantly small bite angle of the chelate and interaction of near phenyl rings pertaining to opposite dpdpc moieties. Coordination of dpdpc to cobalt prompts its oxidation to the corresponding P , P ′-dioxide.

New chiral diimino and diamino ligands derived from α- d -mannose and α- d -glucose are described. The ligands are obtained by introducing the appropriate nitrogen functions at C(2) and C(3) of the sugar rings. The ability of the new chelates to promote the asymmetric copper(I)-catalysed cyclopropanation of styrene has been investigated. The nature of both the sugars and the chelates is crucial in determining the enantioselectivity of the reaction.

The dicationic palladium(II) and platinum(II) complexes [(PNP)M(C2H4)](BF4)2 (1a, M = Pt; 1b, M = Pd; PNP = 2,6-bis((diphenylphosphino)methyl)pyridine) and [(PPP)Pt(C2H4)](BF4)2 (7; PPP = triphos) catalyze a cross-coupling reaction of ethylene with tri- and tetrasubstituted olefins, which can lead to both hydrovinylation and cyclopropanation products. The product ratio is strongly affected by the choice of the ligand and of the metal, the two limiting cases being 1a and 7, which selectively give the hydrovinylation and the cyclopropanation products, respectively.

The fragment [(chiral diamine)Ag]+ is a very useful reagent, both for the resolution of racemic alkenes and for the 1H or 13C NMR determination of the enantiomeric abundances of chiral olefinic compounds.

This review provides a survey of the key-class of Pt0 complexes of general formula [Pt(N,N′-chelate)(η2-olefin)]. The main spectroscopic, structural and chemical features are discussed, in terms of electronic and steric properties of the ancillary ligands. The versatile reactivity towards electrophiles is described as a very useful entry to PtII compounds with a wide assortment of ligands, such as halido, hydrido, hydrocarbyl, organometal, organoelement and carbene fragments, in some cases stabilised for the first time by the careful choice of the N,N′-ligand. Remarkably, the reactions can be an equilibrium, and their relevant thermodynamic parameters have also been collected, thus allowing a thorough discussion of the electronic and steric factors which affect its position.

The coordinated ethylene molecule in the dicationic complex [(PNP)Pt(CH2=CH2)](BF4)2 (PNP = 2,6-bis(diphenylphosphinomethyl)pyridine) undergoes nucleophilic attack by free internal alkenes, giving the isolable complexes [(PNP)Pt(CH2=CHCH(Me)CMeRR'](BF4)2 (R, R' = H, Me) and providing a new effective pathway for a chemo- and regio-selective catalytic hydrovinylation reaction.

Cationic nitrile platinum(II) complexes of formula [PtMe(RCN)(bipy)]+ undergo nucleophilic addition of carbanions −CH(COX)(COY) (X, Y= Me, OMe), −CH(CO2Me)CN and −CH(CN)2 to afford neutral products. According to the nature of the nucleophile, the organic ligand fragment displays either an imino enol or an enamine isomeric structure. The Pt−N bond can be cleaved upon reaction with acids with formation of the corresponding β-enaminodione.

By using the Corey diamine 1,2-diphenyl-N,N′-bis[(2,4,6-trimethylphenyl)methyl]-1,2-diaminoethane, Copper(I) olefin complexes are prepared. When the olefin is a racemic allylic alcohol, selective coordination of one enantiomer is observed. Cleavage with aqueous HCl or NaCN allows a two-steps resolution affording excellent enantiomeric excess.

Using saturation-transfer experiments and measurements of coalescence temperatures, the effects of phenanthroline ligands on the activation parameters for syn-anti isomerization, syn-anti proton exchange, and apparent rotation in six (eta3-allyl)palladium complexes have been studied. The rates of the processes are increased by the addition of ionic, coordinating ligands such as chloride indicating a pentacoordinated intermediate. By X-ray crystallography the structure of a potential intermediate of this type has been determined. Finally, using 2-(8-methoxy-1-naphthyl)-1,10-phenanthroline, it has been possible both to observe chiral induction on a deuterium-substituted eta3-allyl group and to find additional information on the mechanism of apparent rotation.

The reactions of organomercury halides HgR′(Cl)(R′= Me, Et, But or Ph) with complexes of the type [Pt(dmphen){(Z)-RO2CCHCHCO2R}](dmphen = 2,9-dimethyl-1, 10-phenanthroline; R = Me, Et or But) have been studied. The dmphen ligand with suitable ‘in-plane’ steric hindrance stabilizes five-co-ordinate adducts of general formula [PtCl(HgR′)(dmphen){(Z)-RO2CCHCHCO2R}] when R′= alkyl. An influence of the nature of the Hg–bound hydrocarbyl group on the reaction course is observed. Thus, a cluster containing the Pt–Hg–Pt sequence was obtained when R′= Ph or Cl. The molecular structure of [PtCl(HgMe)(dmphen){(Z)-MeO2CCHCHCO2Me}][space group P21/c; a= 13.079(2), b= 13.167(2), c= 15.495(3)A and β= 94.18(2)°] reveals a large trans influence of the organomercury fragment.

Three cationic five-coordinate platinum(II) complexes bearing alkylmercury fragments as “ligands” have been isolated. The complexes of general formula [Pt(HgR)H2O(dmphen)(Z-R′O2CCH = CHCO2R′] (BF4) ( dmphen = 2,9- dimethyl -1,10- phenanthroline ; R, R ′ = Me ; = R = Me, R ′ = t Bu, R ′ = Me ) are stabilized by the factors operating in related neutral species. Two of the new complexes slowly demercuriate in solution, affording the mononuclear complexes [ Pt(Me)(H 2 O)(dmphen)(Z- R ′ O 2 CCH = CHCO 2 R ′)]( BF 4 ) ( R ′ = Me or t Bu . When R = t Bu , a slow redistribution is observed, yielding the trinuclear cluster [{Pt(dmphen)(Z-MeO2CCH = CHCO2Me(H2O)}2Hg](BF4)2. The structure of this complex has been determined by X-ray analysis.

Alkenes, alkynes, 1,2- and 1,3-dienes react with [MR(N-N)(MeCN)] + (M = Pt or Pd; R = hydrocarbyl group; NN = bidentate nitrogen ligand) to give R-substituted derivatives. The organic fragment is generally retained within the metal environment in η 1 or η 3 coordination, except in the reaction of alkenes with Pd (II) complexes. In this case, a free R-substituted alkene is produced via a relatively fast β-elimination process from a Pd-alkyl intermediate. Different regiochemistries are detected in the reaction between monosubstituted olefins (propene or styrene) and homologous Pt and Pd complexes. The Pt-C bond is always formed with the terminal unsubstituted alkene carbon, while a preference toward the internal carbon, particularly if phenyl-substituted, is observed with Pd species. Neutral [MClR(N-N)] are markedly less reactive. In this case, when M = Pt, the unsaturated organic substrate generally adds to the metal affording fairly stable tbp five-coordinate complexes.

Coordinatively saturated carbene complexes of platinum(II) have been obtained by oxidative addition of [ClCHNMe2]Cl to Pt(0) precursors. The cationic products of general formula [PtCl(CHNMe2)(N,N-chelate)(olefin)]Cl have been characterized through NMR spectroscopy and for [PtCl(CHNMe2)(2,9-Me2-1,10-phen)(Z-MeO2CCHCHCO2Me)]Cl by X-ray diffractometry. The latter species reacts with nucleophiles affording dimethylformamide and the corresponding Pt(0) precursor [Pt(2,9-Me2-1,10-phen)(Z-MeO2CCHCHCO2Me)]. Attempts to obtain related complexes containing carbene groups PtCHY without a heteroatom in α-position (Y = CO2Et, CO2NMe2, CN) have led to the isolation of complexes of formula [PtR(dmphen){η1,η2-CH(Y)O2CCHCHCO2Me}] (R = Me, Ph), formally derived from an intramolecular nucleophilic addition to a carbene intermediate. The X-ray structure of a representative product, [PtMe(dmphen){η1,η2-CH(CO2Et)O2CCHCHCO2Me}], is reported.

Trigonal bipyramidal olefin-platinum complexes of the title chiral diamine (mestien) have been synthetized and their stereochemistry has been investigated by H-1 and C-13 NMR spectroscopy. The molecular structure of the complex PtClMe ((E)-ClCH = CHCl) (mestien) has been determined by X-ray diffraction analysis. The coordinated nitrogen atoms display a single configuration, and a high enantioface selectivity is observed in the coordination of prochiral olefins having a moderate lateral bulk. The selectivity can be correlated to the conformation adopted by the diamine ligand, which shows a remarkable similarity to those calculated for a proposed intermediate in the enantioselective dihydroxylation of olefins by osmium tetraoxide.