Trapping of Three-Center Ir-Sn-X Intermediates in the Reaction of IrI(COD) with Organotin(IV) Halides. X-ray Structure of (COD)Ir(Br)SnMe2Br

Article abstract of DOI:10.1021/ja00224a021

The reaction of Ir^I(COD) with various organotin(IV) halides SnRR'X2 yields dinuclear adducts <2-(Me2NCH2)C6H4>(COD)Ir(X)SnRR'X (X = Cl, R = R'= Me, Ph; X = R = Cl, R'= Me; X = Br, R = R'= Me, Br; X = Br, R = Me, R'= Ph).No reaction was observed with SnMe3Cl.The X-ray structure of <2-(Me2NCH2)C6H4>(COD)Ir(Br)SnMe2Br was determined.Crystals are triclinic, space group P1, with unit-cell dimensions a=10.122(2) Angstroem , b=14.136(2) Angstroem, c=17.310(2) Angstroem, α=66.83(1) deg, β=69.35(1) deg, γ=73.64(2) deg.The crystal structure was solved with direct methods (Ir, Sn, Br) and subsequent difference Fourier techniques.Anisotropic blocked full-matrix least-squares refinement with 6605 observed reflections and 458 parameters converged at R_F=0.0337.The molecule contains an Ir-Sn-Br triangle, which appears to be the result of an Sn-Br bond that is side-on coordinated to Ir.As such it can be envisaged as a unique trapped three-center intermediate in the concerted oxidative addition of a metal-halide bound to a square-planar metal d⁸ complex.