Homoleptic Trichloroacetonitrile Complexes

Two homoleptic cationic trichloroacetonitrile complexes [ M (NCCCl 3 ) 4 ] + [ M + = Li + ( 1 ), Ag + ( 2 )] were synthesized through stabilization with the salts of the weakly coordinating anion [Al(OR F )4] – ( R F = –C(CF 3 ) 3 ). The successful determination of the structures of these two complexes by single‐crystal X‐ray diffraction (SC‐XRD) showed a weak interaction between the weakly coordinating anion (WCA) and the singly charged cation. In case of the more stable lithium compounds, a characterization with vibrational spectroscopy was also possible. The SC‐XRD and Raman data proved a lower coordination power of Cl 3 CCN compared to MeCN. Calculations at PBE0/def2‐TZVPP level indicate that it should lie between MeCN and CH 2 Cl 2 for the coordination in a model silver(I) complex [Ag(L) 2 ] + (L = MeCN, Cl 3 CCN, CH 2 Cl 2 ). Calculation of the free Gibbs reaction energies of the formation of the bis‐acetonitrile, bis‐trichloroacetonitrile and the tetrakis‐trichloroacetonitrile complexes, that were found in the solid state with and without dispersion correction (D3) showed a large effect of dispersion effects on the stability of the trichloroacetonitrile complexes. These results indicate that Cl 3 CCN can be used as weak ligand for metal cations and can be a potentially useful weakly coordinating solvent, if the relatively strong coordination power of MeCN is unwanted. An attempt to synthesize a [Au(NCCCl 3 ) n ] + complex through the reaction of [NO] + [Al(O R F ) 4 ] – with elemental gold led to decomposition of the [Al(O R F ) 4 ] – anion and formation of Cl 3 CCN→Al(O R F ) 3 ( 3 ).