A Kinetic Study on the Reactions of Azolato‐Bridged Dinuclear Platinum( II ) Complexes with Guanosine 5′‐Monophosphate

By using 1 H NMR spectroscopy the reactions of [{ cis ‐Pt(NH 3 ) 2 } 2 (µ‐OH)(µ‐pz)](NO 3 ) 2 ( 1 ), [{ cis ‐Pt(NH 3 ) 2 } 2 (µ‐OH)(µ‐1,2,3‐ta‐ N1 , N2 )](NO 3 ) 2 ( 2 ) and [{ cis ‐Pt( R , R ‐dach)} 2 (µ‐OH)(µ‐pz)](NO 3 ) 2 ( 3 ) with guanosine 5′‐monophosphate (GMP) were monitored spectroscopically in 0.1 M phosphate D 2 O solutions at three different pD values (5.4, 6.9, 8.4). From the investigations some kinetic information was obtained. The reaction rate for all these complexes become higher when the pD decreases. In addition, for the reactions performed in unbuffered solutions (pD 8.2), the reactivity of all the complexes for GMP was found to increase dramatically. The 1:2 reaction products were characterized by 1 H, 195 Pt, and 31 P NMR spectroscopy. Reactions of 2 with GMP include an unusual ligand‐binding isomerization, resulting from the Pt atom migration along the 1,2,3‐triazolato ring. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)