Platinum(IV) complexes of a bulky and exceptionally donating alkyl: 2-adamantyl

Abstract

The 2-adamantyl (2-Ad) group is a particularly challenging alkyl to install on a transition metal, with the only reported 2-adamantyl complexes of platinum being those of Pt(II). The question of whether 2-adamantyl complexes with platinum in the oxidation state +IV can be made and whether they are stable is answered here. The Pt(IV) compound trans-[(bpy)PtMe2(2-Ad)I] (bpy= 2,2’-bipyridine) was synthesized via oxidative addition of iodomethane to [(COD)PtMe(2-Ad)] (COD=1,5-cyclooctadiene) in the presence of bpy. Iodide abstraction with silver triflate (triflate anion, OTf-=CF3SO3-) produced trans-[(bpy)PtMe2(2-Ad)(OTf)]. Both complexes were unambiguously characterized by 1D NMR (1H, 13C) spectroscopy and X-ray crystallography. Both show evidence for the large steric bulk of the 2-adamantyl group (through the conformation of the complex adopted) and also for its exceptionally pronounced trans-influence (very long bonds to iodide/triflate trans to adamantyl). Both of the new platinum(IV) adamantyl complexes were extremely stable, even to prolonged heating.