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1.
Dalton Trans ; 2020 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-32103221

RESUMO

The synthesis and characterization of a series of N-heterocyclic carbene (NHC) complexes of Au(iii), (NHC)AuCl3, is described. High yields are obtained when the corresponding Au(i) species (NHC)AuCl are oxidized with inexpensive aqua regia. The oxidation is in some cases accompanied by substitution and/or anti addition of Cl2 across the backbone C[double bond, length as m-dash]C bond of unsaturated NHC ligands.

2.
Angew Chem Int Ed Engl ; 59(4): 1516-1520, 2020 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-31710154

RESUMO

A highly asymmetric AuIII η3 -allyl complex has been generated by treating Au(η1 -allyl)Br(tpy) (tpy=2-(p-tolyl)pyridine) with AgNTf2 . The resulting η3 -allyl complex has been characterized by NMR spectroscopy and X-ray crystallography. DFT calculations and variable temperature 1 H NMR suggest that the allyl ligand is highly fluxional.

3.
J Am Chem Soc ; 141(43): 17452-17458, 2019 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-31589434

RESUMO

The bench-stable cationic bis(σ-B-H) aminoborane complex [Fe(PNPNMe-iPr)(H)(η2-H2B = NMe2)]+ (2) efficiently catalyzes the semihydrogenation of internal alkynes, 1,3-diynes and 1,3-enynes. Moreover, selective incorporation of deuterium was achieved in the case of 1,3-diynes and 1,3-enynes. The catalytic reaction takes place under mild conditions (25 °C, 4-5 bar H2 or D2) in 1 h, and alkenes were obtained with high Z-selectivity for a broad scope of substrates. Mechanistic insight into the catalytic reaction, explaining also the stereo- and chemoselectivity, is provided by means of DFT calculations. Intermediates featuring a bisdihydrogen moiety [Fe(PNPNMe-iPr)(η2-H2)2]+ are found to play a key role. Experimental support for such species was unequivocally provided by the fact that [Fe(PNPNMe-iPr)(H)(η2-H2)2]+ (3) exhibited the same catalytic activity as 2. The novel cationic bisdihydrogen complex 3 was obtained by protonolysis of [Fe(PNPNMe-iPr)(H)(η2-AlH4)]2 (1) with an excess of nonafluoro-tert-butyl alcohol.

4.
Chem Commun (Camb) ; 54(79): 11104-11107, 2018 Oct 02.
Artigo em Inglês | MEDLINE | ID: mdl-30221264

RESUMO

A (N,CAr,CAlk) Au(iii) pincer complex has been synthesized from Au(OAc)3 (OAc = OCOCH3) and 2-(3,5-di-tert-butylphenyl)pyridine (L1) involving a Csp3-H bond activation by electrophilic substitution. In agreement with DFT calculations, the resulting complex significantly improves the performance of Au(tpy)(OAcF)2 (tpy = 2-(p-tolyl)pyridine, OAcF = OCOCF3) in the catalytic trifluoroacetylation of acetylene.

5.
Dalton Trans ; 47(8): 2589-2601, 2018 Feb 20.
Artigo em Inglês | MEDLINE | ID: mdl-29384547

RESUMO

The syntheses and characterization of nine new cyclometalated ruthenium complexes are reported. These structures consist of Ru(ii) with bipyridine and phenylpyridine ligands which are substituted with ester or carboxylate groups. Two of the complexes were extensively studied and their properties were compared to those of two previously reported structures. The identities of the compounds were confirmed by NMR, HR-MS and single crystal XRD, and the electronic properties were investigated by UV-Vis spectroscopy. DFT and TD-DFT calculations showed that the intense absorbances in the visible region of the spectrum of these cyclometalated complexes are due to electronic excitations to virtual orbitals located on the carboxylated ligands. These results indicate that the compounds are promising candidates as sensitizers for more efficient photocatalysis with sunlight. Further, the carboxylate groups should facilitate their use as linkers in metal-organic frameworks.

6.
Acta Crystallogr E Crystallogr Commun ; 73(Pt 7): 971-974, 2017 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-28775863

RESUMO

The title compound, {[MgPtCl2(C12H6N2O4)(C3H7NO)2(H2O)]·C3H7NO} n , is a one-dimensional coordination polymer. The structure consists of Pt-functionalized bi-pyridine ligands connected by MgII cations, as well as coordinating and non-coordinating solvent mol-ecules. The PtII cation is coordinated by the two N atoms of the bi-pyridine moiety and two Cl atoms in a square-planar fashion. This coordination induces an in-plane bend along the bi-pyridine backbone of approximately 10° from the linear ideal of a conjugated π-system. Likewise, the coordination to the MgII cation induces a significant bowing of the plane of the bi-pyridine of about 12°, giving it a distinct curved appearance. The carboxyl-ate groups of the bi-pyridine ligand exhibit moderate rotations relative to their parent pyridine rings. The MgII cation has a fairly regular octa-hedral coordination polyhedron, in which three vertices are occupied by O atoms from the carboxyl-ate groups of three different bi-pyridine ligands. The remaining three vertices are occupied by the O atoms of two di-methyl-formamide (DMF) mol-ecules and one water mol-ecule. The one-dimensional chains are oriented in the [01-1] direction, and non-coordinating DMF mol-ecules can be found in the space between the chains. The shortest inter-molecular O⋯H contacts are 2.844 (4) and 2.659 (4) Å, suggesting moderate hydrogen-bonding inter-actions. In addition, there is a short inter-molecular Pt⋯Pt contact of 3.491 (1) Å, indicating a Pt stacking inter-action. Some structure-directing contribution from the hydrogen bonding and Pt⋯Pt inter-action is probable. However, the crystal packing seems to be directed primarily by van der Waals inter-actions.

7.
Organometallics ; 36(18): 3664-3675, 2017 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-29805192

RESUMO

Aryl sulfamates are valuable electrophiles for cross-coupling reactions because they can easily be synthesized from phenols and can act as directing groups for C-H bond functionalization prior to cross-coupling. Recently, it was demonstrated that (1-tBu-Indenyl)Pd(XPhos)Cl (XPhos = 2-dicyclohexylphosphino-2',4',6'-triisopropylbiphenyl) is a highly active precatalyst for room-temperature Suzuki-Miyaura couplings of a variety of aryl sulfamates. Herein, we report an in-depth computational investigation into the mechanism of Suzuki-Miyaura reactions with aryl sulfamates using an XPhos-ligated palladium catalyst. Particular emphasis is placed on the turnover-limiting oxidative addition of the aryl sulfamate C-O bond, which has not been studied in detail previously. We show that bidentate coordination of the XPhos ligand via an additional interaction between the biaryl ring and palladium plays a key role in lowering the barrier to oxidative addition. This result is supported by NBO and NCI-Plot analysis on the transition states for oxidative addition. After oxidative addition, the catalytic cycle is completed by transmetalation and reductive elimination, which are both calculated to be facile processes. Our computational findings explain a number of experimental results, including why elevated temperatures are required for the coupling of phenyl sulfamates without electron-withdrawing groups and why aryl carbamate electrophiles are not reactive with this catalyst.

8.
Dalton Trans ; 45(37): 14719-24, 2016 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-27283880

RESUMO

Incorporation of the simple, readily available, building blocks ethylene, water and acetonitrile into Au(tpy)(OCOCF3)2 (tpy = 2-(p-tolyl)pyridine) in a one-step reaction leads to high yields of a new 6-membered ring gold(iii) metallacycle complex. The metallacycle has been characterized spectroscopically and crystallographically, and the mechanism of its formation has been investigated with the aid of DFT calculations.

9.
Inorg Chem ; 55(5): 1986-91, 2016 Mar 07.
Artigo em Inglês | MEDLINE | ID: mdl-26894842

RESUMO

The structure and properties of two new UiO-67-type metal-organic frameworks, along with their linker synthesis and powder and single crystal synthesis, are presented. The new MOFs, UiO-67-Me and UiO-67-BN, are based on 3,3'-dimethylbiphenyl and 1,1'-binaphthyl linker scaffolds, and show a much higher stability to water than the thoroughly investigated UiO-67, which is based on the biphenyl scaffold. On the basis of structure models obtained from single crystal X-ray diffraction, it is seen that these linkers are partly shielding the Zr cluster. The new materials have higher density than UiO-67, but show a higher volumetric adsorption capacity for methane. UiO-67-BN exhibits excellent reversible water sorption properties, and enhanced stability to aqueous solutions over a wide pH range; it is to the best of our knowledge the most stable Zr-MOF that is isostructural to UiO-67 in aqueous solutions.

10.
Dalton Trans ; 45(13): 5504-13, 2016 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-26905649

RESUMO

The contribution of Au(III) species to catalysis is still debated due to the limited number of characterized intermediates with this oxidation state. In particular, the coordination of alkenes and alkynes to Au(III) followed by insertion into Au(III)-X bonds has been suggested but rarely proven experimentally. Here, these reactions are explored by means of DFT and CCSD(T) calculations considering [AuX3(L)] and [AuX2(L)2](+) complexes. In these complexes, L = ethylene and acetylene have been chosen as substrates of high interest and representative of any unsaturated organic substrate, whereas X is Cl, Me or H, as found in metal salts and as model for intermediates involved in catalysis. Isoelectronic Pt(II) complexes are also considered for comparison. Ethylene coordination occurs preferentially perpendicular for all X except H, whereas for acetylene, coordination takes place in-plane for all X except Cl. These coordination isomers can represent either minima (intermediates) or saddle points (transition states) on the potential energy surface, depending on X. NBO analysis shows how this variety of structures results from the combination of electronic (M-L donation and back-donation) and steric (cis L-X repulsion) effects. With the sole exception of [AuMe2(ethylene)2](+), rotation of the unsaturated ligand and insertion into a cis Au-X bond involve low to moderate energy barriers, ΔG(‡) = 2.5 to 23.5 kcal mol(-1), and are thermodynamically feasible, ΔG = 4.3 to -47.2 kcal mol(-1). The paucity of experimental observations for such reactions should thus be caused by other factors, like the participation of the intermediates and products in competitive side reactions including the reductive elimination of XCHnCHnX (n = 1 or 2).

11.
Eur J Med Chem ; 94: 163-74, 2015 Apr 13.
Artigo em Inglês | MEDLINE | ID: mdl-25768700

RESUMO

The pure enantiomers of the N-(2-, 3-, and 4-(2-aminocyclopropyl)phenyl)benzamides hydrochlorides 11a-j were prepared and tested against LSD1 and MAO enzymes. The evaluation of the regioisomers 11a-j highlighted a net increase of the anti-LSD1 potency by shifting the benzamide moiety from ortho to meta and mainly to para position of tranylcypromine phenyl ring, independently from their trans or cis stereochemistry. In particular, the para-substituted 11a,b (trans) and 11g,h (cis) compounds displayed LSD1 and MAO-A inhibition at low nanomolar levels, while were less potent against MAO-B. The meta analogs 11c,d (trans) and 11i,j (cis) were in general less potent, but more efficient against MAO-A than against LSD1. In cellular assays, all the para and meta enantiomers were able to inhibit LSD1 by inducing Gfi-1b and ITGAM gene expression, with 11b,c and 11g-i giving the highest effects. Moreover, 11b and 11g,h strongly inhibited the clonogenic potential of murine promyelocytic blasts.


Assuntos
Inibidores Enzimáticos/química , Inibidores Enzimáticos/farmacologia , Histona Desmetilases/antagonistas & inibidores , Leucemia/tratamento farmacológico , Leucemia/genética , Tranilcipromina/química , Animais , Antineoplásicos/química , Antineoplásicos/farmacologia , Ensaios de Seleção de Medicamentos Antitumorais/métodos , Regulação Leucêmica da Expressão Gênica/efeitos dos fármacos , Humanos , Leucemia/patologia , Leucemia Promielocítica Aguda/tratamento farmacológico , Leucemia Promielocítica Aguda/patologia , Camundongos , Camundongos Endogâmicos , Monoaminoxidase/metabolismo , Inibidores da Monoaminoxidase/química , Inibidores da Monoaminoxidase/farmacologia , Estereoisomerismo , Relação Estrutura-Atividade , Tranilcipromina/farmacologia
12.
J Am Chem Soc ; 136(28): 10104-15, 2014 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-24946167

RESUMO

The Au(III) complex Au(OAc(F))2(tpy) (1, OAc(F) = OCOCF3; tpy = 2-p-tolylpyridine) undergoes reversible dissociation of the OAc(F) ligand trans to C, as seen by (19)F NMR. In dichloromethane or trifluoroacetic acid (TFA), the reaction between 1 and ethylene produces Au(OAc(F))(CH2CH2OAc(F))(tpy) (2). The reaction is a formal insertion of the olefin into the Au-O bond trans to N. In TFA this reaction occurs in less than 5 min at ambient temperature, while 1 day is required in dichloromethane. In trifluoroethanol (TFE), Au(OAc(F))(CH2CH2OCH2CF3)(tpy) (3) is formed as the major product. Both 2 and 3 have been characterized by X-ray crystallography. In TFA/TFE mixtures, 2 and 3 are in equilibrium with a slight thermodynamic preference for 2 over 3. Exposure of 2 to ethylene-d4 in TFA caused exchange of ethylene-d4 for ethylene at room temperature. The reaction of 1 with cis-1,2-dideuterioethylene furnished Au(OAc(F))(threo-CHDCHDOAc(F))(tpy), consistent with an overall anti addition to ethylene. DFT(PBE0-D3) calculations indicate that the first step of the formal insertion is an associative substitution of the OAc(F) trans to N by ethylene. Addition of free (-)OAc(F) to coordinated ethylene furnishes 2. While substitution of OAc(F) by ethylene trans to C has a lower barrier, the kinetic and thermodynamic preference of 2 over the isomer with CH2CH2OAc(F) trans to C accounts for the selective formation of 2. The DFT calculations suggest that the higher reaction rates observed in TFA and TFE compared with CH2Cl2 arise from stabilization of the (-)OAc(F) anion lost during the first reaction step.

13.
J Am Chem Soc ; 136(20): 7300-16, 2014 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-24824779

RESUMO

Despite widespread use of complexes of the type Pd(L)(η(3)-allyl)Cl as precatalysts for cross-coupling, the chemistry of related Pd(I) dimers of the form (µ-allyl)(µ-Cl)Pd2(L)2 has been underexplored. Here, the relationship between the monomeric and the dimeric compounds is investigated using both experiment and theory. We report an efficient synthesis of the Pd(I) dimers (µ-allyl)(µ-Cl)Pd2(IPr)2 (allyl = allyl, crotyl, cinnamyl; IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene) through activation of Pd(IPr)(η(3)-allyl)Cl type monomers under mildly basic reaction conditions. The catalytic performance of the Pd(II) monomers and their Pd(I) µ-allyl dimer congeners for the Suzuki-Miyaura reaction is compared. We propose that the (µ-allyl)(µ-Cl)Pd2(IPr)2-type dimers are activated for catalysis through disproportionation to Pd(IPr)(η(3)-allyl)Cl and monoligated IPr-Pd(0). The microscopic reverse comproportionation reaction of monomers of the type Pd(IPr)(η(3)-allyl)Cl with IPr-Pd(0) to form Pd(I) dimers is also studied. It is demonstrated that this is a facile process, and Pd(I) dimers are directly observed during catalysis in reactions using Pd(II) precatalysts. In these catalytic reactions, Pd(I) µ-allyl dimer formation is a deleterious process which removes the IPr-Pd(0) active species from the reaction mixture. However, increased sterics at the 1-position of the allyl ligand in the Pd(IPr)(η(3)-crotyl)Cl and Pd(IPr)(η(3)-cinnamyl)Cl precatalysts results in a larger kinetic barrier to comproportionation, which allows more of the active IPr-Pd(0) catalyst to enter the catalytic cycle when these substituted precatalysts are used. Furthermore, we have developed reaction conditions for the Suzuki-Miyaura reaction using Pd(IPr)(η(3)-cinnamyl)Cl which are compatible with mild bases.

14.
Inorg Chem ; 52(8): 4217-28, 2013 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-23537322

RESUMO

The equilibrium solid-state structure of the experimentally synthesized but incompletely characterized Zn4O(FMA)3 is revised with the help of density functional theory computational methods. The electronic structure, formation energy, chemical bonding, and optical properties of Zn4O(FMA)3 and its heavier congener Cd4O(FMA)3 have been systematically investigated. The calculated bulk moduli for Zn4O(FMA)3 and Cd4O(FMA)3 are similarly small (and slightly smaller than the previously reported values for MOF-5), indicative of relatively soft materials. Their estimated band-gap values are ca. 3.2 eV (somewhat lower than that of MOF-5, 3.4-3.5 eV), indicating semiconducting character. The optical properties including dielectric function ε(ω), refractive index n(ω), absorption coefficient α(ω), optical conductivity σ(ω), reflectivity R(ω), and electron energy-loss spectrum L(ω) of M4O(FMA)3 (M = Zn, Cd) were systematically studied. Analysis of chemical bonding reveals that the M-O bonds are largely ionic, with an increase in ionicity from Zn to Cd. The total energy calculations establish that compounds M4O(FMA)3 have large negative formation energies, ca. -80 and -70 kJ·mol(-1) for Zn and Cd, respectively. Whereas Zn4O(FMA)3 has already been synthesized, the results suggest that the heavier congener Cd4O(FMA)3 might be experimentally accessible.

15.
Acta Crystallogr Sect E Struct Rep Online ; 69(Pt 2): m73-4, 2013 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-23424422

RESUMO

In the title compound, [Cu(2)Cl(4)(C(12)H(8)N(2)O(4))(2)]·4C(3)H(7)NO, which contains a chloride-bridged centrosymmetric Cu(II) dimer, the Cu(II) atom is in a distorted square-pyramidal 4 + 1 coordination geometry defined by the N atoms of the chelating 2,2'-bipyridine ligand, a terminal chloride and two bridging chloride ligands. Of the two independent dimethyl-formamide mol-ecules, one is hydrogen bonded to a single -COOH group, while one links two adjacent -COOH groups via a strong accepted O-H⋯O and a weak donated C(O)-H⋯O hydrogen bond. Two of these last mol-ecules and the two -COOH groups form a centrosymmetric hydrogen-bonded ring in which the CH=O and the -COOH groups by disorder adopt two alternate orientations in a 0.44:0.56 ratio. These hydrogen bonds link the Cu(II) complex mol-ecules and the dimethyl-formamide solvent mol-ecules into infinite chains along [-111]. Slipped π-π stacking inter-actions between two centrosymmetric pyridine rings (centroid-centroid distance = 3.63 Å) contribute to the coherence of the structure along [0-11].

17.
Phys Chem Chem Phys ; 14(14): 4713-23, 2012 Apr 14.
Artigo em Inglês | MEDLINE | ID: mdl-22382620

RESUMO

The chemical bonding, electronic structure, and optical properties of the experimentally available metal-organic framework IRMOF-14 and its metal-substituted analogues M-IRMOF-14 (M = Zn, Cd, Be, Mg, Ca, Sr, Ba), which contain a pyrene-2,7-dicarboxylate linker group, have been systematically investigated using DFT calculations. The unit cell volume and atomic positions were optimized with the Perdew-Burke-Ernzerhof (PBE) functional and showed good agreement between experimental and theoretical equilibrium structural parameters for Zn-IRMOF-14. The calculated bulk moduli indicate that the whole M-IRMOF-14 series are soft materials. The estimated band gap from DOS calculations for the M-IRMOF-14 series is ca. 2.5 eV, essentially independent of the metal ion and indicative of nonmetallic character. The band gap value is distinctly different from those calculated previously for the M-IRMOF-1 (benzene-1,4-dicarboxylate linker; ca. 3.5 eV) and M-IRMOF-10 (biphenyl-4,4'-dicarboxylate linker; ca. 3.0 eV) series and this confirms that the identity of the linker is a key parameter to control band gaps in an isoreticular series of main-group MOFs. In view of potential uses of MOFs in organic semiconducting devices such as field-effect transistors, solar cells, and organic light-emitting devices, the linear optical properties of these materials were also investigated. Comparisons are made with the M-IRMOF-1 and M-IRMOF-10 series.

18.
Acta Crystallogr Sect E Struct Rep Online ; 67(Pt 8): o1929-30, 2011 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-22090974

RESUMO

The asymmetric unit of the title structure, C(14)H(30)N(2)O(4) (2+)·2PF(6) (-), contains the anion and half of the cation, the latter being completed by a crystallographic twofold axis. The cation has a cage structure with the ammonium H atoms pointing into the cage. These H atoms are shielded from inter-molecular inter-actions and form only intra-molecular contacts. There are short inter-molecular C-H⋯F inter-actions in the structure, but no conventional inter-molecular hydrogen bonds.

19.
Acta Crystallogr Sect E Struct Rep Online ; 67(Pt 8): o1958-9, 2011 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-22090998

RESUMO

The asymmetric unit of the title molecular salt, C(14)H(30)N(2)O(4) (2+)·SiF(6) (2-), contains half of both the anion and the cation, both ions being completed by a crystallographic twofold axis passing through the Si atom. The cation has a cage structure with the ammonium H atoms pointing into the cage. These H atoms are shielded from inter-molecular inter-actions and form only intra-molecular contacts. There are short inter-molecular C-H⋯F inter-actions in the structure, but no conventional inter-molecular hydrogen bonds.

20.
Acta Crystallogr Sect E Struct Rep Online ; 67(Pt 5): m617-8, 2011 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-21754331

RESUMO

In the title compound, [Pt(CH(3))(3)I(C(12)H(12)N(2))], the Pt(IV) atom is six-coordinated in a slightly distorted octa-hedral configuration with one CH(3) group and the I atom forming a near perpendicular axis relative to the square plane formed by the bipyridine ligand and the two remaining CH(3) groups. The CH(3) group trans to the I atom has a slightly elongated bond to Pt compared to the other CH(3) groups, indicating a difference in trans influence between iodine and the bipyridine ligand.

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