Synthesis, structure, and stereochemistry of five-coordinate platinum(II)-olefin complexes with a chiral diamine

New five-coordinate platinum(II) complexes of general formula [PtCl2(diamine)(olefin)], where diamine = (R,R)-N,N′-dimethyl-N,N′-bis(α-methylbenzyl)-1,2-ethanediamine (R,R-mben) and olefin = acrolein (AA), acrylonitrile (AN), fumarodinitrile (FN), maleic anhydride (MA), and maleimide (MI) were prepared and characterized. The crystal structures of the already known ethene (1) and propene (2) complexes have been determined by X-ray diffraction studies. Both compounds crystallize in the tetragonal space group P43212 with four molecules per unit cell. Lattice parameters (25°C) are a = b = 13.016 (3) Å, c = 13.719 (4) Å and a = b = 13.180 (2) Å, c = 13.850 (2) A for complexes 1 and 2, respectively. The whole geometry corresponds to a trigonal bipyramid with the chlorine atoms in the axial positions. The olefin and the diamine ligand lie in the equatorial plane. The two prochiral nitrogen atoms have equal absolute configurations identical with that of the asymmetric carbon atoms of R,R-mben. 1H NMR spectra are reported and discussed in order to get information on the rotation of the olefinic ligand and other stereochemical features of the complexes. © 1980 American Chemical Society.