REACTIONS OF CATIONIC PALLADIUM(II) METHYL AND VINYL COMPLEXES WITH ALKYNES

[(phen)Pd(CH3)(OEt2)](+)[BAr'(4)](-) (phen = 1,10 phenanthroline, Ar' = 3,5-(CF3)(2)C6H3) reacts with RC=CR' to form the eta(2)-alkyne compl exes [(phen)Pd(CH3)(eta(2)-RC=CR'](+) [BAr'4](-) (5a, R = R' = SiMe3; 5b, R=C6H5, R' = H). In contrast, the reaction of the diimine complexe s N=C(R)C(R)=NAr)Pd(CH3)(NCCH3)](+)[BAr'(4)](-)(1-3) (Ar = 2,6-(CH3)(2 )C6H3, 2,6-(i-Pr)(2)C6H3; R = H, CH3, 1/2BIAN) with HC=CR' (R' = H, t- Bu) yielded the alkyne insertion products =C(R)C(R)=NAr)Pd(CH=C(R)CH3) (NCCH3)(+)[BAr'(4)](-) (3) while the reaction of 1-hexyne with 1a yiel ded a mixture of the 2,1- and 1,2-insertion products [(N-N)Pd-(C(C4H9) =CHCH3)(NCCH3)](+)[BAr'(4)](-) and [(N-N)Pd(CH=C(C4H9)(CH3)(NCCH3)](+) [BAr4](-) respectively. The vinyl complexes [(N-N)Pd(CH=CRCH3)(NCCH3)] (+)[BAr'4](-) react with acetylene to form the eta(1)-dienyl complexes [(N-N)Pd(CH=CHCH=CRCH3)(NCCH3)](+)[BAr'4](-) which then react with ac etylene and rearrange to form the novel 5-ethylidene-2-cyclopenten-1-y l complexes [(N-N)Pd(eta(3)-C(CH3)(R)C5H5)](+)[X](-). (R = H, t-BU; X = BAr'4, O3SCF3) (8).