Mercury(II) Complexes of AnionicN-Heterocyclic Carbene Ligands: Steric Effects of the Backbone Substituent

Mercury(II) complexes (Me-maloNHC(Dipp))HgCl (1b), (t-Bu-maloNHC(Dipp))HgCl (2b) and (t-Bu-maloNHC(Dipp))HgMe (2c) supported by anionicN-heterocyclic carbenes have been obtained in good yields from the reaction of the potassium salt ofN-heterocyclic carbene ligand precursors and mercury(II) salts, HgCl(2)and MeHgI. These molecules have been characterized by(1)H-NMR,C-13-NMR and IR spectroscopy and elemental analysis. X-ray crystal structures of1band2bare also presented. Interestingly, complex1bis polymeric {(Me-maloNHC(Dipp))HgCl}(n)in the solid state, as a result of inter-molecular Hg-O contacts, and features rare three coordinate mercury sites with a T-shaped arrangement, whereas the (t-Bu-maloNHC(Dipp))HgCl (2b) is monomeric and has a linear, two-coordinate mercury center. The formation of T-shaped structure and the aggregation of complex1bis attributable to the reduced steric demand of theN-heterocyclic carbene ligand backbone substituent.