Synthesis and characterization of Pt(II) complexes with amine and carboxylato ligands. Crystal structure of (1,1-cyclobutanedicarboxylato)di(ethylamine)platinum(II)·H2O

Two methods for the synthesis of compounds of the type cis-PtA2X2 (A2=bidentate amine or two monodentate amines and X2=bidentate or two monodentate carboxylato ligands) were evaluated. The compounds were characterized by multinuclear NMR and IR spectroscopies. The 195Pt NMR chemical shifts were in the range −1615 to −1976 ppm, the higher field values corresponding to the complexes containing bidentate ligands. The coupling constants 3J(195Pt–1H) are approximately 35 Hz, while the 2J(195Pt–1HN) are about 70 Hz. One coupling constant 2J(195Pt–13C) (53 Hz) was also measured. The crystal structure of the compound, cis-Pt(1,1-cyclobutanedicarboxylato)(C2H5NH2)2·H2O belongs to the P21/n space group with a=9.468(5), b=9.365(4), c=16.473(7) Å, β=105.08(3)°, Z=4 and R1=0.0576. The PtN bond distances are 1.992(5) and 2.020(5) Å, while the PtO bonds are 2.000(4) and 2.015(4) Å. The molecules are held together by intermolecular H-bonds involving the lattice water molecules and the two free carbonyl O atoms and between the amino H atoms and the Pt-bonded CO groups.