NMR studies of transformations of aminoacid complexes of Pt(II) and Pd(II) in solution. 2. Bisalaninates

Abstract

Synthetic procedures are suggested for diastereomers of Pt(II) and Pd(II) bischelates with alanine: cis- and trans-Pt(l-Ala)2 , trans-Pt(l-Ala)fd-Ala), trans-Pd(l-Ala)2 , and trans-Pd(l-Ala)(d-AIa). Methods of their isolation in individual solid state are proposed.1H,13C, and195Pt NMR spectral investigations are reported for the individual diastereomers and for M(Ala)2 racemates in DMSO solution. The trans-isomers of Pd(II) bisalaninates in DMSO solution are transformed into an equilibrium mixture of cis- and trans-isomers. For Pt(II) complexes, the cis ↔ trans equilibrium was also found but the equilibration rate is much lower than that for Pd(II) bischelates for both cis- and trans-isomer. An equilibrium 2M(l-Ala)(d-Ala) ⇌ M(l-Ala)2+M(d-Ala)2 is also shown to exist.