Daniele Zuccaccia

Daniele Zuccaccia
University of Udine | UNIUD · DI4A

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79
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Publications (79)
Article
New methods for the introduction of fluoro substituents are in great demand, owing to the present importance of fluorinated bioactive compounds. Here we report a simple strategy for the synthesis of a new class of β-fluorinated paraconic acid derivatives. Methyl and ethyl hexanoyl succinates were fluorinated by Selectfluor®, then reduced by a mild...
Article
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Metabolomics provides a description of the phenotype of an organism and complementary biochemical information to genomics and proteomics. The purpose of this research was to depict the metabolite profile of faecal samples from dogs fed three different diets through NMR spectroscopy analysis. Samples were collected from 14 dogs fed a commercial extr...
Article
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The coordination ability of the [(ppy)Au(IPr)]2+ fragment [ppy = 2-phenylpyridine, IPr = 1,3-bis(2,6-di-isopropylphenyl)-imidazol-2-ylidene] towards different anionic and neutral X ligands (X = Cl−, BF4−, OTf−, H2O, 2-butyne, 3-hexyne) commonly involved in the crucial pre-equilibrium step of the alkyne hydration reaction is computationally investig...
Article
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The diacetate complexes trans-[Ru(κ¹-OAc)2(PPh3)2(NN)] (NN = ethylenediamine (en) (1), 2-(aminomethyl)pyridine (ampy) (2), 2-(aminomethyl)pyrimidine (ampyrim) (3)) have been isolated in 76–88% yield by reaction of [Ru(κ²-OAc)2(PPh3)2] with the corresponding nitrogen ligands. The ampy-type derivatives 2 and 3 undergo isomerization to the thermodynam...
Article
With the aim of rationalizing the experimental counterion- and solvent-dependent reactivity in the gold(I)-catalyzed Meyer-Schuster rearrangement of 1-phenyl-2-propyn-1-ol, a computational mechanistic study unraveled the unexpected formation of a gold-oxetene intermediate...
Article
For the first time, NHC-Au-X [NHC = (1,3-bis(2,6-di-isopropylphenyl)-imidazol-2-ylidene, X⁻ = BF4⁻, OTf⁻, OTs⁻, TFA⁻] catalysts were tested in the cycloisomerization of N-(prop-2-yn-yl)benzamide to 2-phenyl-5-vinylidene-2-oxazoline in a wide set of green solvents. We found that most of these solvents (cyclohexanone, isopropyl acetate, MIBK, ethyl l...
Article
There is considerable interest in dynamic materials featuring modular components with nano-scale dimensions and controlled responsiveness to external stimuli. Supramolecular polymers are a class of materials that fulfil all these conditions well. Here, we present a family of host–guest supramolecular polymers that combine the outstanding complexing...
Article
[AuCl(NHC)(ppy)]Cl (1) and [AuCl(PPh3)(ppy)]OTf (2) complexes [ppy = 2-phenylpyridine, NHC = 1,3-bis(2,6-di-isopropylphenyl)-imidazol-2-ylidene] successfully catalyze the hydration of alkynes in γ-valerolactone (GVL), under acid-free conditions. The solution structure, reactivity, and catalytic properties of (1) and (2) were established by means of...
Article
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Several mononuclear ruthenium complexes containing bulky diphosphines have been easily prepared from acetate ruthenium precursors. The cyclohexyl complex [Ru(η²-OAc)2(DCyPF)] (1-cy; DCyPF = 1,1′-bis(dicyclohexylphosphino)ferrocene) is synthesized from [Ru(η²-OAc)2(PPh3)2] and DCyPF in toluene at reflux, whereas the ethylenediamine (en) derivatives...
Article
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The ligand HCNNOMe (6-(4-methoxyphenyl)-2-aminomethylpyridine) is easily prepared from the commercially available 6-(4-methoxyphenyl)pyridine-2-carbaldehyde by reaction of hydroxylamine and hydrogenation (H2, 1 atm) with Pd/C. The pincer complexes cis-[RuCl(CNNOMe)(PPh3)2] (1) and [RuCl(CNNOMe)(PP)] (PP = dppb, 2; dppf, 3) are synthesized from [RuC...
Article
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The monocarbonyl complexes [RuCl2(CO)(PR3)(NN)] (R = Cy, NN = en 1, ampy 2; R = iPr; NN = en 3) have been prepared in a one pot reaction from [RuCl2(CO)(dmf)(PPh3)2], PR3 and the NN ligand in CH2Cl2. Treatment of the [Ru(OAc)2(CO)(PPh3)2] with NN ligands in methanol gives the cationic derivatives [Ru(OAc)(CO)(PPh3)(NN)]OAc (NN = en 4, ampy 5) in wh...
Chapter
In this chapter, the role of ion pairing in the mechanism of the reactions promoted by gold(i) catalysts L–Au–X is elucidated by means of both experimental findings and theoretical calculations. The synergy of the approach allowed the full elucidation of the role of the counterion X⁻. The catalytic performance in the alkoxylation and hydration of a...
Article
The bidentate HCNN dicarbonyl ruthenium complexes trans,cis-[RuCl 2 (HCNN)(CO) 2 ] (1-3) and trans,cis-[RuCl 2 (ampy)(CO) 2 ] (1a) were prepared by reaction of [RuCl 2 (CO) 2 ] n with 1-[6-(4′-methylphenyl)pyridin-2-yl]methanamine, benzo[h]quinoline (HCNN), and 2-(aminomethyl)pyridine (ampy) ligands. Alternatively, the derivatives 1-3 were obtained...
Article
L-Au-X [L = 1,3-bis(2,6-di-isopropylphenyl)-imidazol-2-ylidene {NHCiPr}, tris(3,5-bis(trifluoromethyl)phenyl)phosphine {PArF}, bis(imino)acenaphtene-1,3-bis(2,6-di-isopropylphenyl)dihydroimidazol-2-ylidene {BIAN}, 1,3-bis(2,6-di-isopropyl-phenyl)dihydroimidazol-2-ylidene {NHCCH2}, bis(tert-butylamino)methylidene {NAC}, 2-(di-tert-butylphosphino)bip...
Article
The dicarbonyl complex RuCl2(L)2(CO)2 (1) was easily prepared by reaction of ruthenium chloride hydrate with formic acid and L (L = (2,6-Me2C6H3)PPh2) in ethanol at reflux, via the [RuCl2(CO)2]n intermediate. Alternatively, 1 was obtained from [RuCl2(CO)3]2 and L by CO elimination. Reaction of 1 with NEt3 in toluene at reflux afforded the cyclometa...
Article
NHC-Au-OTf [NHC = (1,3-bis(2,6-di-isopropylphenyl)-imidazol-2-ylidene] catalyst was tested in the alkoxylation and hydration of alkynes in a wide set of neoteric solvents for the first time. We found that most of these solvents (ethyl lactate, glycerol, propylene carbonate, d-limonene, γ-valerolactone, p-cymene) are comparable or better solvents wi...
Article
The Pd-catalysed Suzuki-Miyaura reaction is a powerful and widely used method for the synthesis of asymmetric biaryls, that has found increasing industrial application for the production of pharmaceuticals, fine chemicals, and materials. Despite its widespread popularity, there is still a need to better understand some features of the whole process...
Article
In this work DFT calculations have been performed to investigate the anion/ligand interplay in the reaction mechanism of alkoxylation of alkynes promoted by gold(I) catalysts of general formula [L-Au-X] (L = NHC, P(tBu)3 and X = OTs–, OTf–, BF4–, TFA–) on the basis of available experimental data. The observed catalytic efficiency trend in this seri...
Article
The Dewar-Chatt-Duncanson (DCD) model provides a successful theoretical framework to describe the nature of the chemical bond in transition metal compounds and is especially useful in structural chemistry and catalysis. However, how to actually measure its constituents (substrate to metal donation and metal to substrate back-donation) is yet uncert...
Article
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O2 insertion into a Au(i)-H bond occurs through an oxidative addition/recombination mechanism, showing peculiar differences with respect to Pd(ii)-H, for which O2 insertion takes place through a hydrogen abstraction mechanism in the triplet potential energy surface with a pure spin transition state. We demonstrate that the spin-forbidden Au(i)-hydr...
Article
NHC-Au-X (NHC = 1,3-bis(2,6- diisopropylphenyl)imidazol-2-ylidene, X− = BArF−, BF4−, SbF6−, OTf−, NTf2−, ClO4−, OTs−, TFA−) catalysts were tested in the hydration of alkynes. A complete rationalization of the counterion effect enabled us to develop a highly efficient methodology under solvent-, silver-, and acid-free conditions. Thus, it was possib...
Article
Full-text available
We have conducted a theoretical exploration of the ligand electronic effect in the protodeauration step of a model gold(I) cyclization reaction, for which experimental data are available. The mechanism of the protodeauration is investigated through a density functional theory (DFT) approach, and the electron-donating power of the ligand is quantifi...
Article
Herein, we synthesized and characterized through NMR and X-ray techniques a new set of [(NHC)-Au-X] complexes (NHC = 1,3-bis(2,6-diisopropylphenyl)-imidazol-2-ylidene), differing in the counterion X- (X- = OMs-, NO3-, ClO4-, 2,2,3,3,4,4,5,5,6,6,7,7,7-tridecafluoroheptanoate (PFHp-)). All of these complexes, together with those already known having...
Article
The cyclization reaction of 2-(1-hexynyl)dimethylaniline (S) on gold(I) has been studied by NMR spectroscopy, in order to characterize the ion pair structure of the product, [LAuSc]BF4. The latter is a good model for the catalytic intermediate between the nucleophilic attack and the protodeauration step of a typical gold catalytic cycle. 19F, 1H HO...
Article
Full-text available
The CO stretching response upon coordination to a metal M to form [(L) n M(CO)] m complexes (L is an auxiliary ligand) is investigated in relation to the σ donation and π back-donation components of the M-CO bond and to the electrostatic effect exerted by the ligand-metal fragment. Our analysis encompasses over 30 carbonyls, in which the relative...
Article
The geometric perturbation of the cyclopropyl ring in [LAu(S)](n+) (S = cyclopropyl(methoxy)carbene) complexes has been recently proposed as an indirect experimental probe of the [LAu](n+) electron-donating power, but experimental data are available only for a phosphine ligand [Brooner et al., Chem. Commun., 2014, 50, 2420, L = P(t-Bu)2(o-biphenyl)...
Article
The effects of the ligand (L) and counterion (X-) are considered the two most important factors in homogeneous gold catalysis, but a rational understanding of their synergy/antagonism is still lacking. In this work, we synthesized a set of 16 gold complexes of the type L-Au-X that differ as follows: (i) L = PPh3 (L1), P(tBu)3 (L2), tris(3,5-bis(tri...
Article
In the last years, it has been demonstrated that the anion plays a key role in gold(I) catalysis, affecting yield, regio- and stereo-selectivity of processes. In order to perform such activity, necessarily the anion has to locate itself close to the reaction center. In this contribution, the level of aggregation of cationic linear gold complexes be...
Article
Full-text available
We analyzed the ligand electronic effect in a gold(I)-catalyzed intramolecular alkyne hydroamination, through a DFT and Charge-Displacement Function (CDF) study. We found that, in the presence of a $\pi$-electron conjugation between the alkyne and the nucleophilic functionality, electron poor ligands modify the coordination mode and the geometric p...
Article
Experimental data suggest that anions that provide a compromise between the hydrogen-bond acceptor and the coordinating powers rather than poor coordinating anions unexpectedly increase the efficiency of L-Au-X (L = ligand, X = anion) catalyzed alkyne alkoxylation reactions, where the nucleophilic attack is the rate-determining step. No systematic...
Article
Even though the Dewar–Chatt–Duncanson model has been successfully used by chemists since the 1950s, no experimental methodology is yet known to unambiguously estimate the constituents (donation and back-donation) of a metal–ligand interaction. It is demonstrated here that one of these components, the metal-to-ligand π back-donation, can be effectiv...
Article
Full-text available
We elucidate the role of the ligand in determining the ion pair structure of the [(NAC)Au(η2-3-hexyne)]+ BF4‒ [(NAC = Nitrogen Acyclic Carbene, also known as ADC = Acyclic Diamino Carbene)] catalysts and how the position of the anion influences their catalytic performances, giving a detailed relationship between the ion pairs structure, determined...
Article
The intermolecular alkoxylation of alkynes is the oldest application of cationic gold(I) catalysts; however, no systematic experimental data about the role of the anion are available. In this contribution, the role of the anion in this catalytic reaction as promoted by a N-heterocyclic carbene-based gold catalyst, [(NHC)AuX] (X=BARF−, BF4−, OTf−, O...
Article
In this study we have examined 42 [(L)M(CO)n](±/0) complexes (M = Ni and Au), including neutral ligands, such as phosphines and carbenes, and anionic ones. For each complex, the carbonyl stretching frequency (νCO) and the amount of charge donated from the ligand to the metal (CT) have been computed on the basis of DFT calculations. For nickel compl...
Article
In this contribution we report a comparative analysis of the chemical bond between an N-heterocyclic carbene and different Au(I) metal fragments of general formula [(NHC)AuL]+ or [(NHC)AuL], where NHC is imidazol-2-ylidene and L is chosen from some ligands frequently used both in coordination and in organometallic chemistry. The focus is on the nat...
Article
High level ab initio calculations have been carried out on an archetypal gold(I)-catalyzed reaction: hydroamination of ethyne. We studied up to 12 structures of possible gold(I)-coordinated species modeling different intermediates potentially present in a catalytic cycle for the addition of a protic nucleophile to an alkyne. The benchmark is used t...
Article
We critically review recent experimental and theoretical investigations into some key aspects of the chemistry of gold(I) complexes of the type [L–Au–S]+X– (L = NHC carbenes and phosphanes, S = alkenes and alkynes, and X– = weakly coordinating counterion). These systems are important intermediates formed during gold-catalyzed nucleophilic additions...
Article
We have studied the ion pair structure of [NHC-Au(η2-3-hexyne)][BF4] (NHC = nitrogen-heterocyclic carbene) by solution NOE NMR spectroscopy and relativistic DFT calculation. The neutral complexes [NHC-AuCl] have been synthesized through an improved, silver-free one-pot synthesis, by reaction (in air and using solvents and substrates without any pre...
Article
Full-text available
The interionic structure of four gold(i) π-alkyne ion pairs, with general formula [(PR(1)(2)R(2))Au(η(2)-3-hexyne)]BF(4) (R(1) = R(2) = (t)Bu, ; R(1) = (t)Bu, R(2) = o-diphenyl, ; R(1) = R(2) = 2,4,6-trimethoxyphenyl, ; R(1) = R(2) = 2,4-di-tert-butylphenoxy, ), was studied by (19)F, (1)H-HOESY NMR spectroscopy. In all the cases the anion locates m...
Article
It's so easy: The readily available and highly water-soluble [IrCl(Hedta)]Na complex is an efficient and robust catalyst for water oxidation to molecular oxygen. The reaction is driven by the reduction of Ce(4+) to Ce(3+) . Its performances (TOF=6.8 min(-1) and TON>12 000) are derived by UV/Vis spectroscopic, volumetric and electrochemical measurem...
Chapter
This chapter deals with the applications of diffusion NMR spectroscopy to investigate supramolecular compounds in solution. It is organized in three main sections: (i) brief description of the basic concepts underlying self-diffusion in solution and measurement of the self-diffusion translational coefficient (Dt) by NMR experiments; (ii) critical d...
Article
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The activity of three [Cp*IrLn] (Cp* = pentamethylcyclopentadienyl) archetypal catalysts ([Cp*Ir (bpy)Cl]Cl (1, bpy = 2,2′-bipyridine), [Cp*Ir(bzpy)(NO3)] (2, bzpy = 2-benzoylpyridine) and [Cp*Ir(H2O)3](NO3)2 (3)) for wateroxidation to molecular oxygen was compared using cerium(IV) ammonium nitrate as a sacrificial oxidant. Kinetic studies were car...
Article
Zirconaaziridinium inner sphere ion pairs (ISIPs) bearing alkyl chains of different lengths, [Cp2Zr(η2-CH2NR1R2)+···X−] (R1 = Me, R2 = C2H5, X− = MeB(C6F5)3−, ZrNC2BN; R1 = Me, R2 = C16H33, X− = MeB(C6F5)3−, ZrNC16BN; R1 = R2 = C18H37, X− = MeB(C6F5)3−, ZrNC18BN; R1 = Me, R2 = Ph, X− = MeB(C6F5)3−, ZrNPhBN; R1 = R2 = C18H37, X− = B(C6F5)4−, ZrNC18B...
Article
Full-text available
The relative anion–cation orientation in [(NHC)Au(alkene)]BF4 ion pairs [NHC = N-Heterocyclic Carbene = 1,3-bis(di-iso-propylphenyl)-imidazol-2-ylidene (IPr) and 4,5-dimethyl-N,N′-bis(2,6-diisopropylphenyl)-imidazol-2-ylidene (MeIPr); alkene = 4-methyl-1-pentene, 2,3-methyl-2-butene and 4-methylstyrene] has been investigated by combining 19F,1H-HOE...
Article
The self-aggregation tendency of [N(CH(3))(2)(C(18)H(37))(2)]X [1X; X(-)=BF(4) (-), PF(6) (-), OTf(-), NTf(2) (-), BPh(4) (-), BTol(4) (-), BAr(F-), and B(C(6)F(5))(4) (-)] salts to form ion quadruples (IQs) and higher aggregates (HAggs) in [D(6)]benzene is investigated by means of diffusion NMR spectroscopy. The experimental results indicate that...
Article
We report on three Ir(iii) molecular catalysts for water oxidation: 1, [Cp*Ir(ppy)Cl]; 2, [Cp*Ir(bzpy)NO(3)]; 3, [Cp*Ir(H(2)O)(3)](NO(3))(2). 2 and 3 are water-soluble and show a long-term activity ca. 2 and 3 times higher than 1. It is remarkable that 3, having the simplest structure, is the catalyst with the highest activity.
Article
The intra- and interionic structures of a mononuclear phosphine gold(I) alkyne complex [(PAr(F)(3))Au(2-hexyne)]BF(4) [1BF(4); Ar(F) = 3,5-bis(trifluoromethyl)phenyl] and its analogous complex [(NHC)Au(2-hexyne)]BF(4) [2BF(4); NHC = 1,3-bis(diisopropylphenyl)imidazol-2-ylidene] have been investigated by combining 1D and 2D multinuclear NMR spectros...
Article
Cyclometalated cationic IrIII complexes with substituted 1,10-phenanthrolines (1, 10-phen), such as [Ir(ppy)2(5-R-1, 10-phen)]Y (ppy = cyclometalated 2-phenylpyridine; R = NO2, H, Me, NMe2; Y- = PF6-, C 12H25SO3-, I-) and [Ir(ppy)2(4-R,7-R-1,10-phen)]Y (R = Me, Ph) are characterized by a significant second-order optical non linearity (measured by t...
Article
Diffusion NMR investigations were carried out in CD2Cl2 for a series of neutral (1–7) and cationic (8–10) square planar palladium complexes. Diffusion data were elaborated through a modified Stokes–Einstein equation that takes into account the size and shape of molecules. The hydrodynamic volume at infinite dilution of all complexes was found to be...
Article
New multicationic organoruthenium dendrimers (RuPF6-Dabit, n=2, 4, 8, 16) have been synthesized by coupling of [Ru(eta(6)-p-cymene)(kappa(3)-dpk-OCH2CH2OH)]X (1PF(6), dpk=2,2'-dipyridyl ketone, X=PF6) with 1,4-diaminobutane (DAB) and polypropylenimine dendrimer DAB-dendr-(NH2)(n), {n=4, 8, 16} mediated by 1,1'-carbonyldiimidazole (CDI). The interme...
Article
The relative anion-cation orientation in [(PPh(3))Au(4-Me-styrene)]BF(4) (1BF(4)) and [(NHC)Au(4-Me-styrene)]BF(4) [2BF(4); NHC = 1,3-bis(di-iso-propylphenyl)-imidazol-2-ylidene] has been investigated by combining (19)F,(1)H-HOESY NMR spectroscopy and Density Functional Theory (DFT) calculations incorporating solvent and relativistic effects. It ha...
Article
The self-aggregation tendency of [RuX(N,N)(η(6)-p-cymene)] [N,N = amino amidate, X = Cl (1) and H (2)] and [Ru(N,N)(η(6)-p-cymene)] [N,N = amido amidate, 3] in various solvents was investigated by diffusion NMR spectroscopy. The proper evaluation of the molecular hydrodynamic volume of the 1−3 monomeric species allowed understanding that 1 and 2 ar...
Article
Arene ruthenium(II) complexes containing bis(pyrazolyl)methane ligands have been prepared by reacting the ligands L′ (L′ in general; specifically L1 = H2C(pz)2, L2 = H2C(pzMe2)2, L3 = H2C(pz4Me)2, L4 = Me2C(pz)2 and L5 = Et 2C(pz)2 where pz = pyrazole) with [(arene)RuCl(μ-Cl)] 2 dimers (arene = p-cymene or benzene). When the reaction was carried ou...
Article
This review summarizes the results recently obtained by our research group investigating the non-covalent aggregation of coordination compounds in solution through NMR spectroscopy. First, systems that can undergo only weak non-covalent interactions, such as dispersive and dipole–dipole ones, are considered; successively, coordination compounds tha...
Article
The interaction between [RuCl(AA)(cymene)]n supramolecular aggregates (1, AA = alpha-amino-acidate = alpha-aminoisobutyrate; 2, AA = N,N-dimethyl-Gly; 3, AA = Ala; 4, AA = Pro; cymene = 4-isopropyltoluene) and ionic species derived from NBu4PF6 and KPF6 is investigated through diffusion NMR measurements and 19F,1H-hetero-nuclear Overhauser effect s...
Article
A study was conducted to investigate self-aggregation tendency of zirconocenium ion pairs, which model polymer-chain-carrying species in aromatic and aliphatic solvents with low polarity. The study synthesized model zirconocenium ion pairs, with alkylic chains of variable length and investigated them through advanced nuclear magnetic resonance (NMR...
Article
The synthesis of the Boc-protected 1-(2-aminoethyl)-3-methylimidazolium salts [BocNHCH2CH2ImMe]X [2]X (X=I, PF6) and their straightforward transformation into [NH2CH2CH2ImMe]X [3]X is reported. The reaction between [2]X and Ag2O leads to the formation in the solid state of three different bonding motifs: a biscarbene salt [(NHC–NHBoc)2Ag]PF6 ([4]PF...
Article
This tutorial review deals with the methodological procedures that can be used to obtain accurate molecular sizes in solution from diffusion NMR spectroscopy. The critical aspects associated with the estimation of the size of molecules from the measured translational self-diffusion coefficient, using the Stokes-Einstein equation, are highlighted an...
Article
Complexes [Ru(arene)(κ3-dpk-OR]X (dpk = 2,2‘-dipyridylketone) were synthesized, and their interionic structure was investigated through an integrated approach based on diffusion and NOE NMR experiments and X-ray single-crystal studies. PGSE NMR results indicated that the highest aggregation tendency occurred for complex 2BF4 (arene = p-cymene and R...
Article
A simple methodology for rapidly and accurately determining the hydrodynamic olume of single ions and ion pairs, based on the combination of information deri ed from diffusion NMR spectroscopy and conductometry, is proposed.
Article
The interionic structure of complexes [Ru(η6-Arene){(2-R-C6H4)NC(Me)−C(Me)N(2-R-C6H4)}Cl]X was investigated by an integrated experimental (PGSE diffusion and NOE NMR spectroscopy and X-ray single-crystal studies) and theoretical (DFT and ONIOM calculations) approach. PGSE NMR experiments indicated that ion pairing is the main aggregative process in...
Article
Rhodium(III) and iridium(III) complexes containing bis(pyrazolyl)methane ligands (pz = pyrazole, L' in general; specifically, L1 = H2C(pz)2, L2 = H2C(pzMe2)2, L3 = H2C(pz4Me)2, L4 = Me2C(pz)2), have been prepared in a study exploring the reactivity of these ligands toward [Cp*MCl(mu-Cl)]2 dimers (M = Rh, Ir; Cp* = pentamethylcyclopentadienyl). When...
Article
PGSE NMR measurements show that complexes [RuCl(AA)(Arene)] have a marked tendency to self-aggregate in solution mainly through NH···X intermolecular H-bonding. Nanosized aggregates (rH = 20.8 Å) form under favorable conditions (solvents with low relative permittivity, elevated concentration, little encumbered ligands) containing up to 133 [RuCl(AA...
Article
(S)-2-Pyridyl-imino-[2.2]paracyclophane ligands 1 and 2 were synthesized by a condensation reaction of 2-COR-C5H4N (1: R=H; 2: R = Me) with enantiopure (�)-S-amino-[2.2]-paracyclophane. The reactions of 1 and 2 with [Ru(g6-cymene)Cl(l-Cl)]2 afforded complexes [Ru(g6-cymene)Cl(N,N)]X (3: N,N = 1; 4: N,N = 2; X� ¼ BPh� 4 ; PF� 6 ;BF� 4 ) that were co...
Article
The aggregation tendency of complexes [Ru(eta6-cymene)(N,O)Cl]X [N,O = 2-benzoylpyridine (2-bzpy), 1, and 2-acetylpyridine (2-acpy), 2, X- = BPh4- or PF6-] has been studied by means of PGSE NMR experiments. It was found that complexes with PF6- as counterion are mainly present in CD2Cl2 as ion pairs at low concentration, as a mixture of ion triples...
Article
The self-assembly between bidentate cavitand ligands and mono/dinuclear metal precursors to give cavitand frameworks has been explored. For this purpose, two new cavitands bearing AB and AC phenylpyridyl moieties at the upper rim have been synthesized. A series of self-assembled molecular dimers featuring fac-Re(CO)(3)Br as metal corners have been...
Article
PGSE NMR measurements have been carried out for DAB-dendr-(NH2)n [n = 4 (Dab4), 8 (Dab8), 16 (Dab16), 32 (Dab32), and 64 (Dab64)] and DAB-dendr-[NH(O)COCH2CH2OC(O)C5H4Rh(NBD)]n [n = 4 (Rh-Dab4), 8 (Rh-Dab8), 16 (Rh-Dab16), 32 (Rh-Dab32), and 64 (Rh-Dab64)] in CD2Cl2 and CD3OD as a function of the concentration. The hydrodynamic radius (rH) and, con...
Article
[reaction: see text] The trans-bis[2-(2-chloroethyl)pyridine]palladium chloride (1) has been prepared and structurally characterized by X-ray spectroscopy and computational study. The X-ray structure of 1 is consistent with the trans isomer (with respect to Pd). The NMR spectrum and the computational study are in agreement with an equilibrium in CD...
Article
Changing the counteranion along the series Br, BF4, PF6, SbF6 in their ion-paired 2-pyridylmethyl imidazolium salts causes the kinetic reaction products with IrH5(PPh3)2 to switch from chelating N-heterocyclic carbenes (NHCs) having normal C2 (N path) to abnormal C5 binding (AN path). Computational work (DFT) suggests that the AN path involves C-H...
Article
The utility of PGSE NMR measurements in determining hydrodynamic radii (rH) and volumes (VH) of small- and medium-size molecules (3 Å < rH < 6 Å) was evaluated by performing measurements for a variety of pure deuterated solvents and their solutions containing the internal standard TMSS [tetrakis(trimethylsilyl)silane] also in the presence of a vari...
Article
The interionic structure, kinetic stability, and degree of anion encapsulation of coordination cages 1 were studied by PGSE, NOE, and EXSY NMR techniques. The rate constants for the formation/dissociation processes at 296 K were obtained independently via (1)H-NOESY and (19)F-NOESY experiments giving, respectively, k(obs) = 0.30 +/- 0.04 s(-1) in C...
Article
Diffusion NMR measurements and ONIOM (B3PW91:UFF) calculations show that amino amidate and acidate half-sandwich Ru(II) precatalysts for transfer hydrogenation have a remarkable tendency to form dimers and even larger aggregates in several solvents, including isopropanol, that is, the solvent used in the catalysis reaction.