Copper(I) and Silver(I) Bis(trifluoromethanesulfonyl)imide and Their Interaction with an Arene, Diverse Olefins, and an NTf 2 − ‐Based Ionic Liquid

The chemistry of coinage metal bis(triflyl)imides of technological interest, CuNTf 2 and AgNTf 2 , their synthesis and complexes with excess of comparatively weakly coordinating NTf 2 − as well as with ether, olefins, and the arene mesitylene are described. The existence of the solvent‐free pure phase [CuNTf 2 ] ∞ has not been evidenced so far. Contrary to the literature, in which the preparation of [CuNTf 2 ] ∞ is supposed to be carried out by reacting mesityl copper, [Cu(Mes)] 5 , and HNTf 2 , we found that in fact this reaction leads reproducibly to the interesting copper diarene sandwich complex [Cu(η 3 ‐MesH) 2 ][Cu(NTf 2 ) 2 ] ( 1 ) (MesH=1,3,5‐trimethylbenzene). The unexpectedly stable molecular etherate [Cu(Et 2 O)(NTf 2 )] ( 2 ) turned out to be the best precursor for CuNTf 2 having only an inert and easily exchangeable solvent ligand. The coordination mode of NTf 2 − in 1 and 2 as well as in the hitherto unknown crystalline phase of [AgNTf 2 ] ∞ ( 3 ) is described. The complex formation, which takes place when dissolving 2 or 3 in the room temperature ionic liquid (RTIL) [emim]NTf 2 ([emim] + =1‐ethyl‐3‐methylimidazolium), has been studied. Furthermore, the reaction of 1 – 3 towards the diolefins 1,5‐cyclooctadiene (COD), 2,5‐norbornadiene (NBD) and isoprene (2‐methylbuta‐1,3‐diene) and towards ethylene has been investigated. The products 4 – 13 of these conversions have been isolated and fully characterized by NMR‐ and IR spectroscopies, mass spectrometry, and elemental‐ and XRD analyses. The potential of [Cu(η 3 ‐MesH) 2 ][Cu(NTf 2 ) 2 ] ( 1 ), [Cu(Et 2 O)(NTf 2 )] ( 2 ) and [AgNTf 2 ] ∞ ( 3 ) as well as of [emim][M(NTf 2 ) 2 ] (M=Cu 4 , Ag 5 ) as chemisorbers for ethylene was studied by NMR spectroscopy.