Biomimetic zinc complexes with a new tripodal nitrogen-donor ligand: Tris[2-(1-methyl-4-tolylimidazolyl)phosphane] (Pim(Me,pTol))

The new potentially threefold-chelating ligand tris[2-(1-methyl-4-tolylimid azolyl)]phosphane (Pim(Me,pTol)) has been prepared. The p-tolyl substituent s on the imidazole rings form a shielded hydrophobic cavity. The first X-ra y-structure analysis of this ligand system confirms the proposed structure. The reaction of Pim(Me,pTol) with ZnX2 salts (X = Cl, Br, I, NO,) yields m onomeric Zn-II complexes. The X-ray crystal structures of [Pim(Me,pTol)ZnCl ](2)(ZnCl4) and [Pim(Me,pTol)ZnNO(3)]NO3 prove that the Zn2+ centres are in a tetrahedral environment with threefold N-imidazole coordination. This ar rangement mimics the active centre of carbonic anhydrase (CA).