The planar Pt(II) monomers [PtMe₂(L–L)] and [(PtMe₂)₂(L′–L′)₂] dimers (L–L = R₂Sb(CH₂)₃SbR₂, o-C₆H₄(CH₂SbMe₂)₂; L′–L′ = R₂SbCH₂SbR₂; R = Me or Ph) are obtained in good yield via reaction of [PtMe₂(SMe₂)₂] with L–L or L′–L′ in benzene. The Pt(IV) stibines, [PtMe₃(L–L)I] (L–L = R₂Sb(CH₂)₃SbR₂, o-C₆H₄(CH₂SbMe₂)₂ or 2 × SbPh₃, SbMePh₂ or SbMe₂Ph) are obtained by treatment of [PtMe₃I] with L–L in chloroform. These represent the first series of stable Pt(IV) stibine complexes. All of the products have been characterised by ¹H, ¹³C{¹H}, ¹⁹⁵Pt NMR spectroscopy, electrospray mass spectrometry and analysis. Crystal structure determinations on [PtMe₃{R₂Sb(CH₂)₃SbR₂}I], [PtMe₃{o-C₆H₄(CH₂SbMe₂)₂}I] and [PtMe₃(SbPh₃)₂I] confirm the distorted octahedral environment at Pt, with fac Me groups and mutually cis Sb donor atoms. The Sb–Pt–Sb angle in the seven-membered chelate ring of the o-C₆H₄(CH₂SbMe₂)₂ complex is ca. 96°, compared to <90° in the complexes with six-membered chelates. The C₁-distibines R₂SbCH₂SbR₂ afford only the dinuclear [(PtMe₃)₂(μ-R₂SbCH₂SbR₂)(μ-I)₂] in which the stibine ligand and two I atoms bridge two Pt atoms giving an edge sharing bioctahedral geometry which has been confirmed by a crystal structure analysis. The Pt(II) species undergo oxidative addition with MeI to give the corresponding Pt(IV) species, while the Pt(IV) species reductively eliminate ethane upon thermolysis.