OXIDATIVE ADDITION-REACTIONS TO NOVEL HETEROTRINUCLEAR IRIDIUM COMPLEXES WITH MIXED BRIDGING LIGANDS - CRYSTAL-STRUCTURE OF [(IR(MU-PZ)(MU-S(T)BU)I-2(CO)[P(OME)(3)])PD-2]

The formation and properties of trinuclear heterobridged complexes of general formula [{Ir(mu-pz)(mu-S(t)Bu)L(2)}(2)-Pd] [L(2) = cycloocta-1 ,5-diene 1, (CO)(2) 2, (CO)[P(OMe)(3)] 3; pz = pyrazolate] are reporte d. Complex 3 reacts with methyl iodide or mercury(II) iodide to give c ompounds -pz)(2)(mu-S(t)Bu)(2)I(X)(CO)(2)[P(OMe)(3)](2)}Pd] [X = Me (4 ) I (5)]. Compound 5 undergoes a further oxidative addition with I-2 t o form [{Ir(mu-pz)(mu-S(t)Bu)-I-2(CO)[P(OMe)(3)]}Pd-2], 6. Compound 6 can be also obtained by direct addition of iodine to complex 3 in a 2: 1 molar ratio. The molecular structure of compound 6 has been determin ed by X-ray diffraction methods. The complex crystallizes in the tricl inic system,space group P ($) over bar 1, with a = 8.763(1) Angstrom, b = 12.023(2) Angstrom, c = 12.713-(2) Angstrom, alpha = 102.086(6)deg rees, beta = 94.108(7)degrees, gamma = 109.174(8)degrees, and Z = 1. R efinement by full-matrix least-squares techniques gave final R = 0.032 2. Complex 6 is trinuclear with two octahedral ''IrI2(CO)[P(OMe)(3)]'' moieties symmetrically connected to a central square-planar Pd atom b ridged through the nitrogens of a pyrazolate group and the S atom of a 2-methyl-2-propanethiolate ligand.