The reaction of cis-[PtCl₂(PPh₃)₂] with one equivalent of N-cyanoacetylurethane, EtO₂CNHC(O)CH₂CN and silver(I) oxide, in dichloromethane at room temperature for short reaction times gives the complex cis-[PtCl{N(CO₂Et)C(O)CH₂CN}(PPh₃)₂] in high yield. This complex is an intermediate to the previously reported platinalactam complex [Pt{N(CO₂Et)C(O)CHCN}(PPh₃)₂]. The new complex was characterised by multinuclear NMR spectroscopy, electrospray mass spectrometry, and a single-crystal X-ray study. The deprotonated cyanoacetylurethane ligand lies in a plane almost perpendicular to the platinum coordination plane. Other metal oxides were studied in place of silver(I) oxide for the synthesis of the platinum amidate complex, but none were as successful as silver(I) oxide.