A Macrocycle with a Pair of endo‐Isocyanides and its Affinity to Gold(I)

A pair of isocyanides pointing towards each other are fixed in a macrocyclic scaffold. The arrangement not only increases their local concentration, it should also enable their linear arrangement in coordination compounds. The macrocyclic diisocyanide ligand 1 is synthesized and fully characterized. Its interaction with gold(I) ions is investigated. While IR‐ and 1H‐NMR‐based titration experiments unraveled a stoichiometry of 2 Au(I) ions per macrocycle 1, the corresponding association constants are studied by UV‐Vis titration experiments. However, the values are above the method’s detection limits and only a lower boundary of an over‐all association constant is determined to be 3.0 x107 m‐1. The kinetics of the complex formation is further analyzed by NMR titration experiments and in spite of a change in the solvent, association constants about one order of magnitude larger than the lower limit determined by the UV‐Vis experiments are obtained.