Square planar complexes [Pt(CNC)L] (CNC = C,N,C-2,6-NC₅H₃(C₆H₄-2)₂; L = tht (tetrahydrothiophene, SC₄H₈, 1), L = CN^tBu (2)) react with TlPF₆ in different Pt/Tl molar ratios (3/1 in the case of 1 and 1/1 in the case of 2) yielding the complexes [{Pt(CNC)(tht)}₃Tl](PF₆) (3) and [Pt(CNC)(CN^tBu)Tl](PF₆) (4), respectively. The structures of 3 and 4 (X-ray) show the presence of Pt-Tl dative bonds unsupported by any bridging ligands. In complex 3, the only Tl centre is simultaneously bonded to three Pt atoms forming a perfect equilateral triangle, with Pt-Tl distances of 2.9088(5) Å, remarkable short. Complex 4 is formed by three "Pt(CNC)(CN^tBu)Tl" units, disposed in a triangular fashion, linked together through η⁶-Tl-arene interactions, and showing Pt-Tl bonds with distances of ca. 3.04 Å. The study of these crystal structures would seem to indicate that the difference between the Pt/Tl ratio found in the complexes 3 and 4 is due to the steric requirements of the L ligand bonded to Pt. NMR studies both in solution and in the solid state shows that the Pt-Tl bond persists in solutions of 3 and 4. The UV-vis spectra of 3 and 4 in solution display the same profiles as those of 1 and 2, which may suggest a partial dissociation of the Pt-Tl bond in solution. However, by DFT calculations it was proved that in this case the formation of the Pt?Tl dative bond does not produce the expected blue-shift in the UV-vis absorptions. The emissive behaviour of 1-4 in solid state and frozen solutions is also studied and included in this work.