Insertion of tin(II) bromide into Pt–X (X = Cl, Br) bond of dimethylplatinum(IV) complexes: A novel polymorphic form of [PtBr2(bpy)]

The platinum(II) complex [PtMe2(bpy)] (bpy = 2,2′-bipyridine) reacted with a large excess of dihaloalkanes X(CH2)nX (n = 1, X = Cl; n = 4, X = Br) to form the platinum(IV) complexes [PtMe2X{(CH2)nX}(bpy)] (n = 1, X = Cl, 1a; n = 4, X = Br, 1b). The reaction of complexes 1a and 1b with SnBr2 resulted in insertion of SnBr2 into Pt–X (X = Cl, Br) bond to afford the trihalostannyl complexes [PtMe2(SnBr2X){(CH2)nX}(bpy)] (n = 1, X = Cl, 2a; n = 4, X = Br, 2b). The synthesis of such trihalostannylplatinum(IV) complexes is reported for the first time. The complex 2a was decomposed in CH2Cl2 solution and single crystals of [PtBr2(bpy)] (3a) were obtained. The X-ray structure determination of 3a revealed a new polymorphic form of [PtBr2(bpy)]. The molecules undergo a remarkable stacking along the b-axis to form a zigzag Pt⋯Pt⋯Pt chain containing both short (3.799 Å) and long (5.175 Å) Pt⋯Pt separations through the crystal. The crystal structure is compared to that of the yellow modification of [PtBr2(bpy)].

The platinum(IV) complexes [PtMe2X{(CH2)nX}(bpy)] (bpy = 2,2′-bipyridine; n = 1, X = Cl; n = 4, X = Br) were synthesized and characterized by NMR spectroscopy and the insertion of SnBr2 into Pt–X (X = Cl, Br) bond of these platinum(IV) complexes is reported. The crystal structure of the novel polymorphic form of [PtBr2(bpy)] shows both short and long Pt⋯Pt separations through the crystal.Figure optionsDownload as PowerPoint slide