The reaction of H
2[PtCl
6] · 6H
2O and (H
3O)[PtCl
5(H
2O)] · 2(18C6) · 6H
2O (18C6 = 18-crown-6) with 9-methylguanine (MeGua) proceeded with the protonation of MeGua forming 9-methylguaninium hexachloroplatinate(IV) dihydrate (MeGuaH)
2[PtCl
6] · 2H
2O (
1).The same compound was obtained from the reaction of Na
2[PtCl
6] with (MeGuaH)Cl.On the other hand, the reaction of guanosine (Guo) with (H
3O)[PtCl
5(H
2O)] · 2(18C6) · 6H
2O in methanol at 60 °C proceeded with the cleavage of the glycosidic linkage
and with ligand substitution to give a guaninium complex of platinum(IV), [PtCl
5(GuaH)] · 1.5(18C6) · H
2O (
2).Within several weeks in aqueous solution a slow reduction took place yielding the analogous guaninium platinum(II) complex, [PtCl
3(GuaH)] · (18C6) · 2Me
2CO (
3).H
2[PtCl
6] · 6H
2O and guanosine was found to react in water, yielding (GuoH)
2[PtCl
6] (
4) and in ethanol at 50 °C, yielding [PtCl
5(GuoH)] · 3H
2O (
5).Dissolution of complexes
2 and
5 in DMSO resulted in the substitution of the guaninium and guanosinium ligands, respectively, by DMSO forming [PtCl
5(DMSO)]
−.Reactions of 1-methylcytosine (MeCyt) and cytidine (Cyd) with H
2[PtCl
6] · 6H
2O and(H
3O)[PtCl
5(H
2O)] · 2(18C6) · 6H
2O resulted in the formation of hexachloroplatinates with N3 protonated pyrimidine bases as cation (MeCytH)
2[PtCl
6] · 2H
2O (
6) and (CydH)
2[PtCl
6] (
7), respectively. Identities of all complexes were confirmed by
1H,
13C and
195Pt NMR spectroscopic investigations, revealing coordination of GuoH
+ in complex
5 through N7 whereas GuaH
+ in complex
3 may be coordinated through N7 or through N9. Solid state structure of hexachloroplatinate
1 exhibited base pairing of the cations yielding (MeGuaH
+)
2, whereas in complex
6 non-base-paired MeCytH
+ cations were found. In both complexes, a network of hydrogen bonds including the water molecules was found. X-ray diffraction analysis of complex
3 exhibited a guaninium ligand that is coordinated through N9 to platinum and protonated at N1, N3 and N7. In the crystal, these NH groups form hydrogen bonds N–H
O to oxygen atoms of crown ether molecules.