Cyclopentadienyl platinum(IV) complexes: 1H, 13C nuclear magnetic resonance and optically active shift reagent study

Abstract

The 1H and 13C nmr parameters for the recently reported complexes (η5-C5H5)PtR1R2R3 where R1, R2, and R3 are combinations of CH3, C2H5, and C(O)CH3 groups are reported and compared to those for known octahedral di- and trimethylplatinium (IV) complexes. The C5H5 group has a relatively weak nmr trans-influence. A chiral shift reagent study on complex 5 (R1 = C(O)CH3, R2 = CH3, and R3 = C2H5) resolved the peaks due to the enantiomers, consistent with its structure and establishing its stereochemical stability. The four groups attached to the platinum atom in 5 differed greatly in their sensitivity to the shift reagent. The methyl groups in complex 4 (R1 = C(O)CH3, and R2 = R3 = CH3) become diastereotopic in the presence of chiral shift reagent. The J(Pt—H) values for 5 were not affected by the shift reagent.