The syntheses and structural characterizations of a Pt-Tl chain [{Pt(bzq)(C₆F₅)₂}Tl(Me₂CO)]_n 1 and two trinuclear Pt₂M clusters (NBu₄)[{Pt(bzq)(C₆F₅)₂}₂Tl] 2 and [{Pt(bzq)(C₆F₅)₂}₂Pb] 3 (bzq = 7,8-benzoquinolinyl), stabilized by donor-acceptor Pt → M bonds, are reported. The one-dimensional heterometallic chain 1 is formed by alternate "Pt(bzq)(C₆F₅)₂" and "Tl(Me₂CO)" fragments, with Pt-Tl bond separations in the range of 2.961(1)-3.067(1) Å. The isoelectronic trinuclear complexes 2 (which crystallizes in three forms, namely, 2a, 2b, and 2c) and 3 present a sandwich structure in which the Tl(I) or Pb(II) is located between two "Pt(bzq)(C₆F₅)₂" subunits. NMR studies suggest equilibria in solution implying cleavage and reformation of Pt-M bonds. The lowest-lying absorption band in the UV-vis spectra in CH₂Cl₂ and tetrahydrofuran (THF) of 1, associated with ¹MLCT/¹L'LCT ¹[5d_π(Pt) → π*(bzq)]/¹[(C₆F₅) → bzq], displays a blue shift in relation to the precursor, suggesting the cleavage of the chain maintaining bimetallic Pt-Tl fragments in solution, also supported by NMR spectroscopy. In 2 and 3, it shows a blue shift in THF and a red shift in CH₂Cl₂, supporting a more extensive cleavage of the Pt-M bonds in THF solutions than in CH₂Cl₂, where the trinuclear entities are predominant. The Pt-Tl chain 1 displays in solid state a bright orange-red emission ascribed to ³MM'CT (M' = Tl). It exhibits remarkable and fast reversible vapochromic and vapoluminescent response to donor vapors (THF and Et₂O), related to the coordination/decoordination of the guest molecule to the Tl(I) ion, and mechanochromic behavior, associated with the shortening of the intermetallic Pt-Tl separations in the chain induced by grinding. In frozen solutions (THF, acetone, and CH₂Cl₂) 1 shows interesting luminescence thermochromism with emissions strongly dependent on the solvent, concentration, and excitation wavelengths. The Pt₂Tl complex 2 shows an emission close to 1, ascribed to charge transfer from the platinum fragment to the thallium [³(L+L')MM'CT]. 2 also shows vapoluminescent behavior in the presence of vapors of Me₂CO, THF, and Et₂O, although smaller and slower than those of 1. The trinuclear neutral complex Pt₂Pb 3 displays a blue-shift emission band, tentatively assigned to admixture of ³MM'CT ³[Pt(d) → Pb(sp)] with some metal-mediated intraligand (³ππ/³ILCT) contribution. In contrast to 1 and 2, 3 does not show vapoluminescent behavior.