The reaction of
trans-[RuCl
2(PPh
3)
3] (Ph = C
6H
5) with 2-thio-1,3-pyrimidine (HTPYM) and 6-thiopurines (TPs) producedmainly crystalline solids that consist of
cis,
cis,
trans-[Ru(PPh
3)
2(
N,
S-TPYM)
2] (
1) and
cis,
cis,
trans-[Ru(PPh
3)
2(
N7,
S-TPs)
2]X
2 (X = Cl
-, CF
3SO
3-). In the case of TPs, other coordination isomers have never been isolated andreported. Instead, the mother liquor obtained after filtration of
1 produced red single crystals of
trans,
cis,
cis-[Ru(PPh
3)
2(
N,
S-TPYM)
2]·2H
3O
+·2Cl
- (
2·2H
3O
+·2Cl
-). Selected ruthenium(II)-thiobase complexes were studied fortheir structural, reactivity, spectroscopic, redox, and cytotoxic properties. Single crystals of
1 contain thiopyrimidinatoanions chelated to the metal center via N and S. The Ru-N bonds are significantly elongated for
1 [2.122(2) and2.167(2) Å] with respect to
2 [2.063(3) Å] because of the trans influence from PPh
3. The coordination pseudo-octahedron for
2 is significantly elongated at the apical sites (PPh
3 ligands). Solutions of cis,cis,trans isomers in airare stable for weeks, whereas those of
2 turn green within 24 h, in agreement with the respective redox potentials.
cis,
cis,
trans- and
trans,
cis,
cis-[Ru(PH
3)
2(
N,
S-TPYM)
2], as optimized through the DFT methods at the Becke3LYPlevel are in good agreement with experimental geometrical parameters (
1 and
2), with cis,cis,trans being morestable than trans,cis,cis by 3.88 kcal. The trend is confirmed by molecular modeling based on semiempirical (ZINDO/1) and molecular mechanics (MM) methods. Cytotoxic activity measurements for
cis,
cis,
trans-[Ru(PPh
3)(
N-THZ)(
N7,
S -H
2TP)
2]Cl
2 (
4) (THZ = thiazole, H
2TP = 6-thiopurine) and
cis,
cis,
trans-[Ru(PPh
3)
2(
N7,
S-HTPR)2]Cl
2 (
5)(HTPR = 6-thiopurine riboside) against ovarian cancer cells A2780/S gave IC
50 values of 17 ± 1 and 29 ± 9
M,respectively. Furthermore, the spectral analysis of HTPYM, TPs, and their Ru(II) complexes in solution shows thatintense absorptions occur in the UVA/vis region of light, whereas standard nucleobases absorb in the UVB region.