cis- and trans-Dichloro(3,6-dihydro-1,2-oxazine-N)(dimethyl sulfoxide-S)-platinum(II)

Both the cis, (I), and trans, (II), isomers of the title complex, [PtCl₂(C₄H₇NO)(C₂H₆OS)], possess relatively undistorted square-planar geometries about the Pt atoms. For (I), cis L-Pt-L angles are in the range 88.8 (2)-91.08 (8)°, while trans angles are 178.61 (8) and 179.4 (2)°. For (II), cis L-Pt-L 86.1 (3)-93.7 (1)°, and trans L-Pt-L 175.5(1) and 179.1 (3)°. The dimethyl sulfoxide (dmso) ligand adopts a normal pyramidal geometry in both complexes. In (I), the S=O bond essentially eclipses the adjacent Pt-N bond, while the oxazine ligand in (I) is twisted so as to avoid steric interactions with the adjacent chloride ligand. By contrast, the dmso ligand in (II) is rotated such that the S=O bond is approximately perpendicular to the square plane, while the oxazine ligand is once again twisted out of the plane by a similar amount as in (I). These are the first structural examples of square-planar platinum(II) complexes containing a 1,2-oxazine ligand.