Inorganic Chemistry, Vol.37, No.15, 3767-3774, 1998
van der Waals radii of Pt(II) and Pd(II) in molecular mechanics models and an analysis of their relevance to the description of axial M center dot center dot center dot H(-C), M center dot center dot center dot H(-N), M center dot center dot center dot S and M center dot center dot center dot M (M = Pd(II) or Pt(II)) interactions
Parameters have been developed for the molecular mechanics modeling of nonbonded interactions involving Pt(II) and Pd(II). The value obtained for the van der Waals radius-about 1.7 Angstrom-accords well with the value proposed by Bondi (J. Chem. Phys. 1964, 68, 441-451). This model has been used to investigate close M ... H(-C), M ... H(-N), M ... H(-O), M ... S, and M ... M (M = Pd(II) or Pt(II)) contacts that have previously been described as weak or agostic bonds. It is argued that the M ... H(-C) interactions are best described as van der Waals interactions that are in the repulsive region but the results are in accord with the description of M ... H(-N) and M ... H(-O) contacts as weak hydrogen bonds. M ... S and M ... M separations in systems without pi-acceptor ligands were accurately reproduced by using the same van der Waals parameters.
Keywords:ORGANOPLATINUM-AMINE SYSTEM;RAY CRYSTAL-STRUCTURE;H-C INTERACTIONS;HYDROGEN-ATOM;PALLADIUM(II) COMPLEXES;PLATINUM(II) COMPLEXES;SCHIFF-BASE;METAL BONDS;LIGANDS;DNA