Oxidative addition of halogens to thiolato-bridged dinuclear iridium(I) complexes. Preparation of several iridium(II) and iridium(III) species. X-ray structure of Ir2(.mu.-Me3CS)2(CO)2(PMe2Ph)2I2 (original) (raw)

Several oxidative reactions of different halogens to dinuclear complexes Ir2(~-t-BuS)z(CO)zLz (L = CO, P(OMe)3, PMezPh, PMeJ have been carried out in nondonor solvents such as toluene or dichloromethane. Different behavior has been observed depending upon the nature of the halogen. Addition of 1 molar equiv of iodine leads to quantitative formation of Ir(I1) complexes of general formula Irz(~-t-BuS)z(CO)zLzIz. Further addition of a second molar equivalent of iodine gives rise to dinuclear iridium(II1) compounds Ir2(~-t-BuS)2(CO)2L21~ Isomorphous complexes have been formed by addition of bromine. However, Ir(I1) species could never be prepared quantitatively since Ir(II1) complexes are always formed preferentially. Oxidative addition of chlorine has also been observed. However, substitution of both thiolato groups by chlorine atoms to give Ir(II1) dinuclear complexes, Ir2(~-Cl),(C0),L2Cl4, is a competitive process. An X-ray diffraction study of Ir2(p-t-BuS)2(CO)z(PMe2Ph)212 has been performed. This compound crystallizes with four formula units in the monoclinic space group Cih-P2,/c in a cell of dimensions a = 16.997 (2) A, b = 14.911 (3) A, c = 13.411 (3) A, and 0 = 91.17 (1) O. On the basis of 3390 unique reflections the structure was refined by full-matrix least-squares techniques to conventional indices R(F) = 0.046 and R,(F) = 0.055. The molecular architectwe of this dinuclear complex can be described in terms of two square-planar pyramids around each iridium atom sharing an edge formed by the two sulfur atoms. The flap angle between the two basal planes is 83.8O. The two iodine atoms occupy the two axial positions, and the two phosphine ligands are mutually cis; the Ir-Ir separation is of 2.702 (1) A. Other bond distances of interest are the following: Ir (1)-1(1) = 2.742 (2) A, Ir(2)-1(2) = 2.712 (2) A, Ir(l)-P(l) = 2.318 (5) A, Ir(2)-P(2) = 2.311 (5) A, Ir (1)-S(1) = 2.383 (5) A, Ir(l)-S(2) = 2.373 (5) A, Ir(2)-S(1) = 2.372 (5) A, Ir(2)-S(2) = 2.391 (5) A.