195Pt NMR of organoplatinum compounds

The ¹⁹⁵Pt chemical shifts of several organoplatinum compounds in solution have been determined. The δ(¹⁹⁵Pt) values of the phosphine-Pt^II and -Pt⁰ compounds lie in separate ranges, and allow the metal-diene systems to be characterized either as metallacyclopentene or as η²-bonded diene. Although the two isomers of bis(η³-allyl)Pt (VIII) formally should be regarded as Pt^II compounds their ¹⁹⁵Pt shifts clearly lie in the region for Pt⁰ compounds. The large separation between the ¹⁹⁵Pt signals and the difference in ¹⁹⁵Pt-T₁ values for the two isomers of VIII are in accord with their having different geometries around the metal.