Imidazole and Triazole Coordination Chemistry for Antifouling Coatings
Scheme 7
(a) Molecular orbitals and ligand field splitting of Cu(II) in a square planar complex and of (b) Zn(II) or Cu(I) in a tetrahedral complex [96]. (a) With regard to cupric complexes, there is possibility for weakly bound counterions or coordinating solvent molecules in axial position and the geometry is then labelled tetragonal (distorted octahedral symmetry). However, the ligand field splitting will be similar in tetragonal and square planar symmetry if one accounts for the important 4s-3dz2 mixing, which effectively lowers the metal dz2 orbital in both symmetries [97]. (b) The ligand field splitting in tetrahedral complexes is the inverse of an octahedral one but with some mixing of the dσ and p-orbitals. The situation with π-interaction is, however, more complicated since the π-interacting ligand orbitals may form both σ- and π-bonds, and the effect on the ligand field splitting will be a reflection of both bonding modes [96, 97].
