The reactions of [Pt-6(CO)(12)](2-) with CH(PPh2)(2) (dppm), CH2=C(PPh2)(2) (P<^>P), and Fe(C5H4PPh2)(2) (dppf) proceed via nonredox substitution and result in the heteroleptic Chini-type clusters [Pt-6(CO)(10)(dppm)](2-), [Pt-6(CO)(10)(P<^>P)](2-), and [Pt-6(CO)(10)(dppf)](2-), respectively. Conversely, the reactions of [Pt-6(CO)(12)](2-) with Ph2P(CH2)(4)PPh2 (dppb) and Ph2PC equivalent to CPPh2 (dppa) can be described as redox fragmentation that afford the neutral complexes Pt(dppb)(2), Pt-2(CO)(2)(dppa)(3), and Pt-8(CO)(6)(PPh2)(2)(C equivalent to CPPh2)(2)(dPPa)(2). The oxidation of [Pt-6(CO)(10)(dPPm)](2-) results in its oligomerization to yield the larger heteroleptic Chini-type clusters [Pt-12(CO)(20)(dPPm)(2)](2-), [Pt-18(CO)(30)(dPPm)](2-), and [Pt-24(CO)(40)(dPpm)(4)](2-) (for the latter there is only IR spectroscopic evidence). All the clusters were characterized by means of IR and P-31 NMR spectroscopies and electrospray ionization mass spectrometry. Moreover, the crystal structures of [NEt4](2)[Pt-6(CO)(10)(dppm)]center dot CH3CN, [NEt4](2)[Pt-12(CO)(20)(dppm)2]center dot 2CH(3)CN. 2dmf, [NEt4](2)EPt12(CO)(20)(dppm)(2)].4dmf, [NEt4](2)[Pt-6(CO)(10)(dPpf)]center dot 2CH(3)CN, Pt-2(CO)(2)(dppa)(3 center dot)0.5CH(3)CN, Pt-8(CO)(6)(PPh2)(2)(C equivalent to PPh2)(2)(dppa)(2)center dot 2thf, and Pt(dppb)(2) were determined by single-crystal diffraction (dmf = dimethylformamide; thf = tetrahydrofuran).