A REVISION OF THE STRUCTURE OF (BIPYRIDYL-N,N')DICYANOPLATINUM(II)

In a previous X-ray crystallographic study of crystals of Pt(bpy)(CN)( 2) (bpy=2,2'-bipyridine) the planar molecules were reported to be exac tly eclipsed, stacked directly on top of one another with a spacing of 3.33 Angstrom so as to form a linear Pt...Pt...Pt chain. A reinvestig ation shows this structure to be incorrect. The presence of weak inter mediate layer lines indicates that the repeat distance along the stack ing direction is 6.66 Angstrom rather than 3.33 Angstrom. Successive m olecules within the stack are rotated by 180 degrees and the resulting Pt-atom chain is slightly zigzag with a Pt...Pt...Pt angle of 168.6(1 )degrees. The implications are discussed of the determination and refi nement of an apparently satisfactory, although grossly wrong, structur e that was based on an incorrect unit cell and an incorrect space grou p.