The tetranuclear [{Pt(CNC)(tht)}₃Tl](PF₆) (tht = tetrahydrothiophene; SC₄H₈; CNC = C,N,C-2,6-NC₅H₃(C₆H₄-2)₂; 2) cluster has been prepared by the reaction of [Pt(CNC)(tht)] (1) and TlPF₆ (molar ratio 3:1) and structurally characterized. The Tl^I atom is bonded to three Pt^II centers bearing a perfect trigonal coordination. The Pt^II-Tl^I bonds are unsupported by any bridging ligand and are the shortest of this kind reported so far [2.9086(5) Å]. These intermetallic bonds persist in a CD₂Cl₂ solution, as shown by the ¹⁹⁵Pt{¹H} NMR spectrum of 2 at 193 K, in which a Pt-Tl coupling of 8.9 kHz is observed.