An FT-ir study of cis study of trans-dichlorodiammineplatinum(II) bound to inosine-5′-monophosphate

Abstract

Inosine-5′-monophosphate disodium salt (5′-IMPNa₂) reacts with cis-dichlorodiammineplatinum(II) (cis-DDP) and its trans-isomer (trans-DDP) to give complexes of the type cis- and trans-Pt(NH₃)₂(IMPNa₂)nCl_2•xH₂O, n = 1 or 2 and Pt(IMPNa₂)_nCl_2•xH₂O, where n = 1, 2, or 3 and x = 0–6. In the 1:2 platinum complexes the nucleotide binds only to the N₇-atom of the purine ring system, while in the 1:1 metal complexes there is indication for Pt–carbonyl interaction (bridging or chelation) in addition to the N₇-bonding at neutral pH values with cis-DDP.Solution FT-ir studies (H₂O and D₂O) showed that the 1:1 species formed with cis-DDP at neutral pH's behaved differently from those with trans-DDP. The carbonyl stretching vibration of the free base at 1685 cm⁻¹ (H₂O) and 1670 cm⁻¹ (D₂O) exhibited marked spectral changes in intensity, shifting, and shape upon complexation, whereas the reaction with the trans-isomer produced only slight perturbations in the above region.