Empleo del visualizador gráfico Jmol en las clases de simetría molecular

El presente trabajo divulga la innovación educativa que se ha desarrollado en la asignatura Química Inorgánica III (QU0924) del tercer curso del Grado en Química en el curso académico 2013/2014, de la Universitat Jaume I (Castellón, España). El objetivo fundamental de nuestro proyecto era dotar a los estudiantes de material didáctico interactivo y diferente, para un mejor aprendizaje de conceptos fundamentales de simetría molecular. En particular, los estudiantes fueron introducidos en el manejo de la interfaz gráfica Jmol, con la que se pueden construir y visualizar modelos tridimensionales.This article reports the educational innovation that has been implemented in the subject Inorganic Chemistry III (QU0924) of the third year of the Chemistry Degree, during the academic year 2013/2014 at the Universitat Jaume I (Castellón, Spain). The main goal of our project was to provide the students with interactive and new didactic material, for a better understanding of the fundamental concepts of molecular symmetry. In particular, the students were introduced to the use of the Jmol graphic interface, very useful for constructing and visualize three-dimensional models

Recent developments in the applications of palladium complexes bearing N-heterocyclic carbene ligands

N-heterocyclic carbene (NHC) ligands have become ubiquitous ligands in the preparation of metal complexes with new catalytic applications. Mainly due to their applications in C-C bond formation reactions, a plethora of novel palladium-NHC complexes has been described, and a large number of review articles describing their chemistry have been published. In an attempt to provide a new vision of the topic, this article will focus our attention on the development of new palladium complexes with NHC ligands, paying special attention to their applications in catalytic processes other than the classical C-C coupling reactions. This article is divided in the following sections: i) design of reusable Pd-NHC complexes, ii) latest advances in the use of Pd- NHC complexes in homogenous catalysis and, iii) other applications of Pd-NHC complexes

Mono and dimetallic pyrene-imidazolylidene complexes of iridium (III) for the deuteration of organic substrates and the C-C coupling of alcohols

Three different Ir(III) complexes with pyrene-containing N-heterocyclic carbenes have been prepared and characterized. Two complexes contain a monodentate pyrene-imidazolylidene ligand, and have the formulae [IrCp*Cl2(pyrene-NHC)] and [IrCp*(CO3)(pyrene-NHC)]. The third complex is a dimetallic complex with a pyrene-di-imidazolylidene bridging ligand, with the formula [{IrCp*(CO3)}2(μ-pyrene-di-NHC)]. The catalytic activity of the three complexes was tested in the H/D exchange of organic substrates, and in the β-alkylation of 1-phenylethanol with primary alcohols. In the deuteration of organic substrates, the carbonate complexes are active even in the absence of additives. The dimetallic complex is the most active one in the catalytic coupling of alcohols, a result that may be interpreted as a consequence of the cooperativity between the two metal centres.We gratefully acknowledge financial support from the MINECO of Spain (CTQ2014-51999-P) and the Universitat Jaume I (P11B2014-02, P11B2015-24

Pincer-CNC mononuclear, dinuclear and heterodinuclear Au(III) and Pt(II) complexes supported by mono- and poly-N-heterocyclic carbenes: synthesis and photophysical properties

A family of cyclometallated Au(III) and Pt(II) complexes containing a CNC-pincer ligand (CNC = 2,6-diphenylpyridine) supported by pyrene-based mono- or bis-NHC ligands have been synthesized and characterized, together with the preparation of a Pt–Au hetero-dimetallic complex based on a Y-shaped tris-NHC ligand. The photophysical properties of all the new species and of two related Ru(II)–arene complexes were studied and compared. Whereas the pyrene-based complexes only exhibit emission in solution, those containing the Y-shaped tris-NHC ligand are only luminescent when dispersed in poly(methyl methacrylate) (PMMA). In particular, the pyrene-based complexes were found to be emissive in the range of 373–440 nm, with quantum yields ranging from 3.1 to 6.3%, and their emission spectra were found to be almost superimposable, pointing to the fluorescent pyrene-centered nature of the emission. This observation suggests that the emission properties of the pyrene fragment may be combined with some of the numerous applications of NHCs as supporting ligands allowing, for instance, the design of biological luminescent agents.We gratefully acknowledge financial support from MINECO of Spain (CTQ2014-51999-P) and the Universitat Jaume I (P11B2014-02). The authors are grateful to the Serveis Centrals d’Instrumentació Científica (SCIC) of the Universitat Jaume I for providing spectroscopic and X-ray facilities. We are very grateful to Prof. M. Concepción Gimeno (CSIC-Universidad de Zaragoza) for the measurement of the photophysical properties of the samples in PMMA films. We are also grateful to Prof. Francisco Galindo (Universitat Jaume I) for his help in the emission lifetime measurements

Structural Features of Mono- and Dimetallic Complexes of Palladium Combining Two Types of Aromatic NHC Ligands

A family of palladium complexes that combine two types of aromatic N‐heterocyclic carbene (NHC) ligands has been prepared starting from dinuclear palladium complexes. Two of the complexes are mono‐metallic and contain a pyrene‐based mono‐NHC and a benzimidazolylidene ligand. The other two are dimetallic and combine a bridging pyrene‐based bis‐NHC ligand with benzimidazolylidene ligands. All new complexes therefore contain two types of NHC ligands that differ in the size of their aromatic backbones coordinated to the same metal center. All complexes have been characterized and the molecular structure of two of them has been confirmed by X‐ray diffraction studies

The Complex Coordination Landscape of a Digold(I) U‐Shaped Metalloligand

Dedicated to Bob Crabtree on the occasion of his 70th birthdayA U‐shaped di‐gold metallotweezer with two pyrene‐imidazolylidene edges and a xanthenyl‐bis‐alkynyl connector was prepared. This metallotweezer acts as metalloligand in the presence of Cu+, Tl+, or Ag+, showing three clearly distinct coordination patterns depending on the cation used. The coordination to Cu+ leads to a complex in which the metalloligand is coordinated in a pincer form. The reaction with Tl+ affords a complex in which the ligand is acting as a ϰ2‐(trans)‐chelate ligand. The reaction with Ag+ leads to a self‐assembled structure, with two silver cations encased inside the cavity of a duplex structure formed by two self‐assembled metallotweezers

N-Heterocyclic Carbenes: A Door Open to Supramolecular Organometallic Chemistry

The field of metallosupramolecular chemistry is clearly dominated by the use of O-, N-, and P-donor Werner-type polydentate ligands. These molecular architectures are of high interest because of their wide range of applications, which include molecular encapsulation, stabilization of reactive species, supramolecular catalysis, and drug delivery, among others. Only recently, organometallic ligands have allowed the preparation of a variety of supramolecular coordination complexes, and the term supramolecular organometallic complexes (SOCs) is gaining space within the field of metallosupramolecular chemistry. While the early examples of SOCs referred to supramolecular architectures mostly containing bisalkenyl, diphenyl, or bisalkynyl linkers, the development of SOCs during the past decade has been boosted by the parallel development of multidentate N-heterocyclic carbene (NHC) ligands. The first examples of NHC-based SOCs referred to supramolecular assemblies based on polydentate NHC ligands bound to group 11 metals. However, during the last 10 years, several planar poly-NHC ligands containing extended π-conjugated systems have facilitated the formation of a large variety of architectures in which the supramolecular assemblies can contain metals other than Cu, Ag, and Au. Such ligands are Janus di-NHCs and trigonal-planar tris-NHCs—most of them prepared by our research group—which have allowed the preparation of a vast range of NHC-based metallosupramolecular compounds with interesting host–guest chemistry properties. Although the number of SOCs has increased in the past few years, their use for host–guest chemistry purposes is still in its earliest infancy. In this Account, we describe the achievements that we have made during the last 4 years toward broadening the applications of planar extended π-conjugated NHC ligands for the preparation of organometallic-based supramolecular structures, including their use as hosts for some selected organic and inorganic guests, together with the catalytic properties displayed by some selected host–guest inclusion complexes. Our contribution describes the design of several Ni-, Pd-, and Au-based metallorectangles and metalloprisms, which we used for the encapsulation of several organic substrates, such as polycyclic aromatic hydrocarbons (PAHs) and fullerenes. The large binding affinities found are ascribed to the incorporation of two cofacial panels with large π-conjugated systems, which provide the optimum conditions for guest recognition by π–π-stacking interactions. We also describe a series of digold(I) metallotweezers for the recognition of organic and inorganic substrates. These metallotweezers were used for the recognition of “naked” metal cations and polycyclic aromatic hydrocarbons. The recognition properties of these metallotweezers are highly dependent on the nature of the rigid connector and of the ancillary ligands that constitute the arms of the tweezer. A peculiar balance between the self-aggregation properties of the tweezer and its ability to encapsulate organic guests is observed

Cation-Driven Self-Assembly of a Gold(I)-Based Metallo-Tweezer

A combination of self-complementary pi-pi-stacking interactions and metallophilic interactions triggered the self-assembly of a new digold(I) metallo-tweezer in the presence of several types of M+ ions. Titrations by fluorescence spectroscopy enabled the determination of the association constants of the resulting inclusion duplex complexes

A D3h-symmetry hexaazatriphenylene-tris-N-heterocyclic carbene ligand and its coordination to iridium and gold: preliminary catalytic studies

A new D3h-symmetry tris-N-heterocyclic carbene ligand has been prepared and coordinated to iridium and gold. The ligand contains an electron-poor hexaazatriphenylene core; thus, the resulting tris-NHC ligand is a poor electron donor. The tris–Au(I) complex was tested in the hydroamination of terminal alkynes and in the three-component Strecker reaction.We gratefully acknowledge financial support from MINECO of Spain (CTQ2014-51999-P) and the Universitat Jaume I (P11B2014-02 and P11B2015-24). We are grateful to the Serveis Centrals d’Instrumentació Científica (SCIC-UJI) for providing the spectroscopic facilities

Supramolecular Control of the Oxidative Addition as a Way To Improve the Catalytic Efficiency of Pincer-Rhodium (I) Complexes

H-1 NMR studies using a cationic complex with a pyridine-di-imidazolylidene pincer ligand of formula [Rh(CNC)(CO)](+) revealed that this compound showed high binding affinity with coronene in CH2Cl2. The interaction between coronene and the planar Rh-I complex is established by means of & pi;-stacking interactions. This interaction has a strong impact on the electron-donating strength of the pincer CNC ligand, which is increased significantly, as demonstrated by the shifting of the & nu;(CO) stretching bands to lower frequencies. The addition of coronene increases the reaction rate of the nucleophilic attack of methyl iodide on the rhodium (I) pincer complex, and also has a positive effect on the performance of the complex as a catalyst in the cycloisomerization of 4-pentynoic acid. These findings highlight the importance of supramolecular interactions for tuning the reactivity and catalytic activity of square-planar metal complexes.Funding for open access charge: CRUE-Universitat Jaume IWe gratefully acknowledge financial support from the Ministerio de Ciencia e Innovación (PID2021-127862NB-I00), and the Universitat Jaume I (UJI-B2020-01 and UJI-B2021-39). We are grateful to the Serveis Centrals d'Instrumentació Científica (SCIC-UJI) for providing with spectroscopic facilities