Mercury(II) electrophiles as electron acceptors. Charge-transfer complexes with organometal and aromatic donors

Novel charge-transfer (CT) absorption bands are reported for electron donor-acceptor complexes of mercuric chloride and a series of tetraalkyltin compounds. The CT transition energies hv_CT are correlated with ionization potentials I_D of the alkylmetals. Steric interactions within these complexes are larger than those previously examined in the corresponding iodine and bromine complexes, which suggests that the mercury(II) acceptor is intimately associated with the organometal donor. The latter coincides with the observation of multiple charge-transfer absorption bands in hexamethylbenzene complexes of various mercury(II) derivatives, shown to arise from distortion of the linear X-Hg-X. Bent structures are proposed for both σ and π complexes of mercury(II) derivatives.