Dipyrromethene‐Triazolylidene Silver Complexes: Synthesis, Structure and Opportunities

Abstract

The synthesis and characterization of unusual silver triazolylidene-containing dipyrromethene complexes are described. The carbene TAD-N 3 C-H obtained from its parent Triazole-Appended Dipyrromethene (TAD-N 4) is an excellent ligand for the complexation of silver, thanks to the proximity between the dipyrromethene scaffold and the triazolylidene. The effect of silver salt stoichiometry on the structure of the complexes was clearly evidenced by 1 H-NMR spectroscopy and Dipyrromethenes (DPM) have been studied in the literature. [1] They constitute key building blocks in the synthesis of pyrrolic macrocycles. [2] Also, their BF 2-complexes (BODIPYs) are well-known for their remarkable optical properties. [3] DPMs present a strong affinity for a large variety of metals, and can be functionalized to afford metallocomplexes displaying original structures with applications in catalysis, [4-8] luminescence [9,10] or in the construction of supramolecular assemblies. [11-13] Most commonly, phosphine [14-16] and carbene [17-21] ligands are used to synthesize silver complexes. In particular, they play a key role in transmetalation reactions. Unexpectedly, to the best of our knowledge, there is only one example of DPM-Ag complex, obtained by addition of a base and (Ph 3 P)AgOTf on an azadipyrromethene solution. [22] In these conditions, a trigonal complex is isolated. Generally, the silver atom interacts with pyrrole double bonds through π interactions. [23] For several years, our group has been involved in the synthesis and the study of a family of functionalized dipyrromethenes, the Triazole-Appended Dipyrromethenes (TADs) (Figure 1). In particular, we have shown that the TAD-N 4-derived BODIPYs present excellent optical properties, both in organic and in aqueous solution. [24] In addition, Zn-TAD-N 4-metallocomplexes [a] A