Synthesis and Electrochemistry of Copper(I) Complexes with Weakly Basic, Fluorinated, and Multicyclic Arenes

Abstract The dinitrogen complex [(N 2 )Cu{Al(OR F ) 4 }] (R F  = C(CF 3 ) 3 ) acts as the precursor for the synthesis of homoleptic, weakly bound Cu(I)‐arene complexes with benzene, fluorinated, and multicyclic arenes. Upon dissolution of [(N 2 )Cu{Al(OR F ) 4 }] in benzene or the fluorinated arenes xFB (x = number of fluorine atoms, x = 1−4), the complexes [Cu(C 6 H 6 ) 2−3 ] + [Al(OR F ) 4 ] − , [Cu(xFB) 2−3 ] + [Al(OR F ) 4 ] − (x = 1−3), or the ion pair [(xFB)Cu{Al(OR F ) 4 }] (x = 4) form. Both the benzene and fluorobenzene complexes are also available in larger scales by oxidation of elemental copper in the respective solvents using [NO] + [Al(OR F ) 4 ] − as an oxidant. A higher degree of fluorination of the arene ligand leads to a weaker coordination of the Cu(I) atom and thus to higher Cu + /Cu redox potentials in solution that reach an unprecedentedly high value of +1.5 V (!) versus the ferrocenium/ferrocene couple in pentafluorobenzene. The versatile applicability of [(N 2 )Cu{Al(OR F ) 4 }] as a “naked” Cu(I) source is demonstrated by complexation reactions with the multicyclic arenes anthracene and hexaphenylbenzene that yielded multiply charged cations. All complexes presented in this work were characterized by their single‐crystal X‐ray diffraction structures.