Re: metal complexes

[<szilagyi ^at^ miat0.vein.hu>]

 Dear Liu Jianling,
 	molecular mechanics studies have been carried out on penta-coordinated
 tungsten carbene complexes using the PCMODEL-PI V4.0 software with a new
 METMOD1 force field, developed for this application. This programme previously
 provided a semi-quantitative guide to structures of transition metal
 complexes using only the streching, van der Waals, and 1,3-interaction.
 	METMOD1 uses all of the six original energy terms of MMX:
 streching, van der Waals, strech-bend, bending, torsion, and electronic
 interactions. Only experimentally determined data for relevant compounds
 were used for parametrization. Slightly distorted trigonal-bipyramidal
 structures with equatorial paralell carbene conformations are found to be
 favoured.
 	Structures calculated by PCMODEL, METMOD1 and ab initio methods are
 compared with the relevant experimental data. All of the RMS fitting errors
 between the METMOD1 and ab initio or experimental structures are less then
 0.07 angstrom.
 Further references:
 Bencze L., Szilagyi R.: J. Mol. Catal., 1992, 76(1-3), 145-156
 Bencze L., Szilagyi R.: J. Organomet Chem., 1994, in press JOM 23894
 Bencze L., Szilagyi R.: J. Mol. Catal., 1994, May, in press
 	We organize a microsymposium on Molecular Modelling in the first
 week of this September. If you are interested in to attend to this school
 do not hesitate to contact us.
 		Sincerelly Yours
 						Rob