A series of metallacyclic platinum(II) bis(sulfonamido) complexes have been synthesised by reaction of cis-[PtCl₂L₂] [L_PPh₃or L₂_1,5-cyclo-octadiene (cod)] with the sulfonamides [RSO₂NHCH₂CH₂NHSO₂R, RSO₂NHCH₂CHMeNHSO₂R or RSO₂NHC₆H₄NHSO₂R; R_Ph or p-C₆H₄Me] and Ag₂O. The products have been characterised by NMR spectroscopy, electrospray mass spectrometry, elemental analysis, and for the complexes [Pt{N(SO₂Ph)CH₂CH₂N(SO₂Ph)}(PPh₃)₂] and [Pt{N(SO₂Ph)C₆H₄N(SO₂Ph)}(cod)], by single-crystal X-ray structure determinations. In both of these complexes, one of the amido nitrogen atoms has the expected approximately planar geometry, but the other nitrogen atom is surprisingly distorted towards a tetrahedral geometry. The more pyramidal nitrogen has a higher trans-influence in the solid state, reflected by a shorter Pt_N bond, and longer cyclo-octadiene Pt_C bond length trans to this nitrogen.