$^{195}Pt$ NMR spectroscopy is used to determine reaction mechanisms, the structure and the stability of complexes formed by reactions of platinum(II) with dicarboxylates. $^{195}Pt$ chemical shifts are sensitive primarily to the set of bound donor atoms and secondarily to the geometry of the complex and structure of the ligands. To understand the complexation behavior and structure of complexes formed, ring size effect of dicarboxylates with various chain size and steric effect of substituents in methylene site between carbonyl groups are investigated.
As the reaction progresses, the number of oxygen donor changes from 0 to 4, the chemicalshifts move into the downfield and the chemical shifts of $Pt(LH-O)Cl_3^{2-}$ (3) (L= ac, ox, mal, mmal, emal, bmal, suc, glu) are similar. $^{195}Pt$ resonances for 3 are independent on the types of ligand which bind to Pt(II). The chemical shift values resulting from the cis-$PtL_2 Cl_2^{2-}$ (L=oxygen donor, ac, ox, mal, suc, glu) seem to depend on the chain size of the dicarboxylate ligands: the chemical shifts of Pt-suc and -glu are given in relatively downfield region compared to those of Pt-ox and -mal, those are given in similar region of the Pt-ac. This suggests that succinate and glutarate may be incapable of forming seven and eight membered chelate rings. A series of substituted malonates forming six-membered ring system, to see the substituent effect of dicarboxylates, are used. The chemical shifts of disubstituted malonates are more downfield than that of monosubstituted. In the monosubstituted malonates, the chemical shifts move to the downfield when the size of alkyl chain increases. However the $^{195}Pt$ chemical shift of methylmalonate was abnormally observed in the most upfield region. From the variable-temperature $^{195}Pt$ NMR of $Pt(mmal)_2^{2-}$ and $Pt(emal)_2^{2-}$, $Pt(mmal)_2^{2-}$ have fast exchange process between syn- and anti-species because of the small methyl group. In contrast, the $Pt(emal...