Synthesis and Characterization of Group 14−Platinum(IV) Complexes

Abstract

The reactions of group 14 compounds MenEX4-n (E = Si, Ge, Sn; X = Cl, Br, I) with electron-rich [PtMe2(diimine)] complexes give facile trans oxidative addition of the E−X bond (E = Si, X = Br, I; E = Ge, Sn, X = Cl, Br, I). The oxidative additions occur more readily for MenEX4-n in the sequences X = I > Br > Cl and E = Sn > Ge > Si. The first stable silylplatinum(IV) complexes have been prepared in this way, and the X-ray crystal structure of [PtIMe2(Me3Si)(bpy)] shows an exceptionally long Pt−I bond length (2.963(1) Å) consistent with the high trans influence of the trimethylsilyl group. 1H NMR studies show that the oxidative addition involving germanium and tin reagents is easily reversible. Several of the platinum(IV)−tin complexes have a second molecule of tin reagent incorporated into the crystal lattice. The X-ray crystal structure of [PtIMe2(Me3Sn)(bpy-tbu2)]2·Me3SnI· CH2Cl2 shows two distinct complexes (1:1 ratio) to be present in the unit cell. The first is the product of trans oxidative addition, [PtIMe2(Me3Sn)(bpy-tbu2)], and the second is [PtIMe2(Me3Sn)(bpy−tbu2)]·Me3SnI. In this second complex the platinum-bound iodo ligand coordinates to the tin center of the Me3SnI molecule to give a trigonal-bipyramidal tin center.