SYNTHESIS OF [IR-2(MU-PZ)(2)(CH3)(CO)(2)(PIPR(3))(2)](- A KEY INTERMEDIATE IN S(N)2 OXIDATIVE ADDITION OF HALOCARBONS TO DINUCLEAR COMPLEXES() )

The unusual compound of formula [Ir-2(mu-Pz)(2)(CH3)(CO)(2)(PiPr(3))(2 )] (ClO4) (3) has been prepared. This complex is the proposed intermed iate species for the S(N)2 oxidative addition of methyl iodide to the dinuclear compound [Ir(mu-Pz)(CO)(PiPr(3))](2) (1). The spectroscopic and X-ray diffraction data obtained for 3, together with EHMO calculat ions and reactivity studies, indicate that the compound can be describ ed as an Ir( III)-Ir(I) species containing a weak metal-metal bond. Th e implications of these electronic features in the regioselectivity of halocarbons oxidative additions to dinuclear complexes are discussed. (C) 1998 Elsevier Science S.A.