Models for the initial stages of oxidative addition.: Synthesis, characterization, and mechanistic investigation of η1-I2 organometallic "pincer" complexes of platinum.: X-ray crystal structures of [PtI(C6H3{CH2NMe2}2-2,6)(η1-I2)] and exo-meso-[Pt(η1-I3)(η1-I2)(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 = Me, 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 organometallic species which contain It in this bonding motif. These compounds can be envisioned as representing the initial stages of oxidative addition of dihalides 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(CH2NMe2)(2)-2,6}]. The role of the metal-bound halide anion as the point of initial attack of I-2 is described. The results of these investigations are discussed in terms of the basic mechanism of oxidative addition and its implications for catalysis.