Isolation and bonding analysis of copper(I)-xenon complex stabilized by weakly coordinating alkoxyaluminate anion.

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Abstract
The first crystalline Cu(I)-Xe complex, Xe-Cu[Al(OR F ) 4 ], 1 , (R F  = C(CF 3 ) 3 ), forms as a salt of the weakly coordinating perfluorinated alkoxyaluminate upon ligand exchange between elemental xenon and Cu(I)-N 2 complex, Cu(N 2 )[Al(OR F ) 4 ]. Despite the lack of relativistic character of the copper ion, 1 is obtained under ambient Xe pressure and at room temperature. The crystal structure reveals that it is a molecular compound where xenon is a terminal ligand to copper with steric factors causing a Cu-Xe bond elongation in comparison with known gas-phase Xe-Cu(I) species. Extensive computational analysis facilitates the interpretation of spectral properties and gives insight into the nature of the bond between Xe and Cu[Al(OR F ) 4 ]. EDA-NOCV and NPA indicate that electrostatic forces between Xe and Cu[Al(OR F ) 4 ] have the largest share of its energy, though orbital interactions between the 5p orbital of Xe and the hybridized 4s/3d orbital of Cu as well as dispersive forces are also significant. Though the Xe-Cu[Al(OR F ) 4 ] bond is fairly weak in comparison with Au + -Xe in the known [Xe-AuAsF 3 ] complex, the isolation of 1 is possible thanks to the use of the weakly coordinating anion and solvent, which are worse ligands to copper than Xe atom.