CCL: barrier of the radical reaction involving transition metall?



Hello All,
 I have to estimate barrier of the following reaction:
   [Pt] + R-X --> [Pt].-X + R.
 Where [Pt] is square-planar platinum(II) complex.
 I have tryed to do PES scan with mixing guess UHF, but there are hard
 convergence problems.
 Is it possible to calculate it with quantum-chemical methods?
 If yes, could someone advice me how to do it, what is the best suitable
 QM method, etc. Or may be there are publications where similar work
 has been done?
 Any suggestions will be appericated.
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 Best regards,
  Gregory Shamov,
  Kazan State University                         mailto:gas5x*at*bancorp.ru