Preparation and structural characterisation of the cation-π complexes [{(Me3Si)2NK} • (tBu-C6H5)]2 and [{(Me3Si)2NK} • (Me3-C6H3)]2

Two new arene solvates [{(Me3Si)(2)NK} center dot (Bu-t-C6H5)](2) (1) and [{(Me3Si)(2)NK} center dot (Me-3-C6H3)](2) (2) have been synthesised and characterised in the solid state by single-crystal X-ray diffraction analyses. Each complex was prepared through dissolution of potassium hexamethyldisilazide (KHMDS) in either tert-butylbenzene or mesitylene followed by crystallisation. The crystal structures of both 1 and 2 are composed of dimeric K2N2 ring aggregates, where each of the metal centres is solvated by either tert-butylbenzene (1) or mesitylene (2) through eta(6)-cation-pi interactions. In addition, the potassium centres within each dimer have a number of intramolecular agostic K center dot center dot center dot C interactions with the methyl groups of the HMDS anion.