Models for the initial stages of oxidative addition. Synthesis, characterization, and mechanistic investigation of eta(1)-I-2 organometallic "pincer"complexes of platinum. X-ray crystal structures of [PtI(C6H3{CH2NMe2}(2)-2,6)(eta(1)-I-2)] and exo-meso-[Pt(eta(1)-I-3)(eta(1)-I-2)(C6H3{CH2N(t-Bu)Me}(2)-2,6)]

The reaction of I-2 With platinum "pincer" complexes of the general formula [PtI(NCN")] (NCN" = [C6H3(CH2NRR')(2)-2,6](-); R = R' = Me or Et; or R = M e, R' = t-Bu) is reported. All three complexes contain an end-on (eta(1)) I -2 unit, and these compounds represent the only known isolable organometall ic species which contain It in this bonding motif. These compounds can be e nvisioned as representing the initial stages of oxidative addition of dihal ides to d(8) transition metal complexes. The complexes [PtI{C6H3(CH2NMe2)(2 )-2,6}-(eta(1)-I-2)] (1) and exo-meso-[PtI3{C6H3(CH2NMe[t-Bu])(2)-2,6}(eta( 1)-I-2)] (3b) have been structurally characterized by single-crystal X-ray diffraction methods. Mechanistic and spectroscopic (IR, Raman, NMR, UV/vis) investigations have led to the conclusion that complex 1 is formed via a 1 ,2,-shift of the dihalide from the primary product [Pt(eta(1)-I-3){C6H3(CH2 NMe2)(2)-2,6}]. The role of the metal-bound halide anion as the point of in itial attack of I-2 is described. The results of these investigations are d iscussed in terms of the basic mechanism of oxidative addition and its impl ications for catalysis.