SYNTHESIS AND CHARACTERIZATION OF GROUP 14-PLATINIUM(IV) COMPLEXES

The reactions of group 14 compounds Me(n)EX(4-n) (E = Si, Ge, Sn; X = Cl, Br, I) with electron-rich [PtMe(2)(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 Me( n)EX(4-n) in the sequences X = I > Br > Cl and E = Sn > Ge > Si. The f irst stable silylplatinum(IV) complexes have been prepared in this way , and the X-ray crystal structure of [PtIMe(2)(Me(3)Si)(bpy)] shows an exceptionally long Pt-I bond length (2.963(1) Angstrom consistent wit h the high traits influence of the trimethylsilyl group. H-1 NMR studi es show that the oxidative addition involving germanium and tin reagen ts is easily reversible. Several of the platinum(IV)-tin complexes hav e a second molecule of tin reagent incorporated into the crystal latti ce. The X-ray crystal structure of [PtIMe(2)(Me(3)Sn)(bpy-(t)bu(2))](2 ) . Me(3)SnI-CH2Cl2 shows two distinct complexes (1:1 ratio) to be pre sent in the unit cell. The first is the product of trans oxidative add ition, [PtIMe(2)(Me(3)Sn)(bpy-(t)bu(2))], and the second is [PtIMe(2)( Me(3)Sn)(bpy-tbu(2))]. Me(3)SnI. In this second complex the platinum-b ound iodo ligand coordinates to the tin center of the Me(3)SnI molecul e to give a trigonal-bipyramidal tin center.