FORCE-FIELD CALCULATIONS ON THE STRUCTURES OF TRANSITION-METAL COMPLEXES .1. APPLICATION TO COPPER(II) COMPLEXES IN SQUARE-PLANAR COORDINATION

The molecular modeling methods have found wide acceptance in the field s of organic chemistry and biochemistry. This study introduces a new a lgorithm to overcome the special problems encountered when extending s tandard force fields to metal-organic and inorganic complexes. The ext ension can easily be incorporated in common modeling programs. The app lication to the complexes of Cu(II) in square-planar coordination vali dates the approach. A general parametrization for Cu(II) consistent wi th the TRIPOS 5.2 force field is developed on the basis of the X-ray s tructures of 27 complexes with nitrogen- and oxygen-coordinated copper . The metal environment can be calculated to better than 2 pm for the bond lengths and 2-degrees for the bond angles. Some larger deviations for the torsion angles can be attributed to the intermolecular intera ctions in the crystal.