First homoleptic MIC and heteroleptic NHC-MIC coordination cages from 1,3,5-triphenylbenzene-bridged tris-MIC and tris-NHC ligands

The preparation of a triphenylbenzene-bridged tris-(1,2,3-triazolium) salt allowed us to obtain the first homoleptic tris-MIC cylinder-like cages of Ag and Au. The silver MIC-based cage reacts with the trisNHC-Ag analogue to form the corresponding heteroleptic NHC–MIC silver cage in an unusual reaction involving the simultaneous exchange of the tris-NHC and tris-MIC ligands.MINECO (CTQ2014-51999-P) and UJI (P11B2014-02).Published versio

Catalytic conversion of alkynes to α-vinyl sulfides mediated by carbene-linker-carbene (CXC) rhodium and iridium complexes

Abstract The catalytic activity of a set of mono- and bimetallic Rh(I) and Ir(I) complexes bearing carbene-linker-carbene (CXC) bis-triazolylidene ligands (with X = O, N) coordinated in a bridging or chelating fashion was evaluated in the hydrothiolation of alkynes. The hydrothiolation of 1-hexyne with thiophenol in the absence of an external base or other additives was selected as a model reaction. All rhodium complexes are highly selective catalysts towards Markovnikov product formation and display superior activity compared to the related iridium derivatives. DFT calculations were carried out to rationalize the reaction mechanism and selectivity of this process. Neutral dinuclear [Rh₂Cl₂(cod)₂(μ-COC)] was found to be the most effective catalyst for this transformation. Its applicability was further studied towards the hydrothiolation of different alkyl and aryl alkynes using predominantly aryl thiols and proved to be one of the most active and selective catalysts towards the α-vinyl sulfide product to date

Strongly Coordinating Ligands To Form Weakly Coordinating Yet Functional Organometallic Anions

Weakly coordinating anions (WCAs) are generally tailored to act as spectators with little or no function. Here we describe the implementation of strongly coordinating dianionic carboranyl N-heterocyclic carbenes (NHCs) to create organometallic -ate complexes of Au(I) that serve both as WCAs and functional catalysts. These organometallic WCAs can be utilized to form both heterobimetallic (Au(I)−/Ag(I)+; Au(I)−/Ir(I)+) and organometallic/main group ion pairs (Au(I)−/(CPh3+ or SiEt3+). Because parent unfunctionalized dianionic carboranyl NHC complex 3 is unstable in most solvents when paired with CPh3+, novel synthesis methodology was devised to create polyhalogenated carboranyl NHCs, which show superior stability toward electrophilic substitution and cyclometalation chemistry. Additionally, the WCAs containing polyhalogenated carboranyl NHCs are among the most active catalysts reported for the hydroamination of alkynes. This investigation has also produced the first examples of a low-coordinate Au(III) center with two cis accessible coordination sites and the first true dianionic carbene. These studies pave the way for the design of functional ion pairs that have the potential to participate in tandem or cooperative small-molecule activation and catalysis