Preparation of platinum(II) complexes with l-serine using KI. X-ray crystal structure, HPLC and 195Pt NMR spectra

The preparation of platinum(II) complexes containing l-serine using K 2[PtCl 4] and KI as raw materials was undertaken. The cis– trans isomer ratio of the complexes in the reaction mixture differed significantly depending on whether KI was present or absent in the reaction mixture. One of the two [Pt( l-ser- N, O) 2] complexes ( l-ser= l-serinate anion) prepared using KI crystallizes in the monoclinic space group P2 12 12 1 with unit cell dimensions a=8.710(2) Å, b=9.773(3) Å, c=11.355(3) Å, Z=4. The crystal data revealed that this complex has a cis configuration. The other [Pt( l-ser- N, O) 2] complex also crystallizes in the monoclinic space group P2 12 12 1 with unit cell dimensions a=7.0190(9) Å, b=7.7445(6) Å, c=20.946(2) Å, Z=4. The crystal data revealed that this complex has a trans configuration. The 195Pt NMR chemical shifts of trans-[Pt( l-ser- N, O) 2] and cis-[Pt( l-ser- N, O) 2] complexes are −1632 and −1832 ppm, respectively. 195Pt NMR and HPLC measurements were conducted to monitor the reactions of the two [Pt( l-ser- N, O) 2] complexes with HCl. Both 195Pt NMR and HPLC showed that the reactivities of cis- and trans-[Pt( l-ser- N, O) 2] toward HCl are different: coordinated carboxyl oxygen atoms of trans-[Pt( l-ser- N, O) 2] were detached faster than those for cis-[Pt( l-ser- N, O) 2].