Structure and reactivity in reactions of dimethyltin(IV) di(azide) and di (isocyanate) with dimethylplatinum(II) complexes

In situ reaction of SnMe2Cl2 with NaN3 or KOCN in methanol or a mixture of acetone/H2O solution has resulted in the formation of SnMe2(N3)2 (1a) and SnMe2(NCO)2 (1b) complexes, respectively. The reaction of dimethylplatinum(II) complexes [PtMe2(NN)], NN = bpy (bpy = 2,2 '-bipyridine) or 4,4 '-Me2bpy (4,4 '-Me2bpy = 4,4 ' dimethyl-2,2 '-dipyridine), with 1a or 1b occurs initially by oxidative addition but the initial platinum(IV) products [PtXMe2(SnMe2X)(NN)], decompose during attempted isolation to give new organoplatinum(II)/(IV) complexes that contain Pt-N3 or Pt-NCO bonds, several of which were characterized crystallographically. The reaction of electron-rich complex [PtMe2(bpy)] (bpy = 2,2 '-bipyridine) with 1a resulted in the formation of the new Pt(IV) complex fac-[PtMe3(N3)(bpy)] (2). However, the similar reaction of 1a or 1b with [PtMe2(4,4 ' Me2bpy)] (4,4 '-Me2bpy = 4,4 '-dimethyl-2,2 '-dipyridine) gave the corresponding Pt(II) complexes [PtMe(N3)(4,4 ' Me2bpy)] (3), or [PtMe(NCO)(4,4 '-Me2bpy)] (4), respectively. The reaction of [PtMe2(4,4 '-Me2bpy)] or [PtMe2(bpy)] with SnMe2Cl2, followed by addition of KOCN, gave [PtCl2(4,4 '-Me2bpy)] (5) or fac-[PtMe3Cl (bpy)] (6), respectively. The crystal architecture in compounds 2-4 and 6 is stabilized by weak hydrogen bonds and pi & sdot;& sdot;& sdot; pi interactions. Further insight was obtained by monitoring the reactions in situ using multinuclear (1H, 13C, 119Sn, 195Pt) NMR spectroscopy in different solvents and by DFT calculations.