NOVEL BINUCLEAR DOUBLY VINYL-BRIDGED IRIDIUM COMPLEXES FORMED BY OLEFINIC C-H ACTIVATION

Treatment of [C(5)H(5)IrX(2)](n) (2:X = Cl; 3:X = Br) with CH2=CHtBu i n the presence of Na2CO3-iPrOH gives, besides the bis(olefin) complex [C5H5Ir(CH2=CHtBu)(2)] (4) the doubly vinyl-bridged iridium(II) compou nd {[C5H5Ir(mu-eta(1),eta(2)-CH=CHtBu)](2)} (5). The related binuclear complex CH2(C5H4)(2)][Ir-2(mu-eta(1),eta(2)-CH=CHtBu)(2)]} (9) was ob tained from {[CH2(C5H4)(2)][IrBr2](2)}(n) (8) and CH2=CHtBu-Na2CO3 in ethanol and characterized by an X-ray structure analysis (monoclinic, C2/c (No. 15), a = 20.050(8), b = 8.843(1), c = 24.25(1) Angstrom, bet a = 99.53(2)degrees, V = 4241 Angstrom(3), Z = 8, R = 0.032, R(w) = 0. 041). Protonation of both 5 and 9 with HBF4 . OEt(2) yields the BF4 sa lts of the unsymmetrical hydridometal cations 10 and 11 in which the v inyl bridges are still intact. The reaction of the binuclear bis(cyclo octene)metal compounds {[CH2(C5H4)(2)][Rh(C8H14)(2)](2)} (14) and {[CH 2(C5H4)(2)][Rh(C8H14)(2)][Ir(C8H142)]} (17) with bromine yields almost quantitatively the polymeric (or oligomeric) dibromo derivatives 16 a nd 18, which could, however, not be converted to vinyl-bridged complex es by treatment with CH2=CHtBu-Na2CO3-ROH.