The complex [IrH2(NCCH3)3(PiPr3)]BF4 (1) reacts with 2-vinylpyridine to form the hydride
[IrH{NC5H4-2-Z-(CHCH)-κ-N,C}(NCCH3)2(PiPr3)]BF4 (3) in a reaction that likely involves
the observed dihydride [IrH2(NC5H4-2-CHCH2-κ-N)(NCCH3)2(PiPr3)]BF4 (2). Crystallization
of the C−H activation product 3 affords the dicationic derivative [IrH{μ-η2-NC5H4-2-(Z-CHCH)-κ-N,C}(NCCH3)(PiPr3)]2(BF4)2 (4). 3 reacts with 2-vinypyridine, CH2CH2, CH⋮CH,
PhC⋮CH, tBuC⋮CH, and PhC⋮CPh to form the corresponding alkyl or alkenyl insertion
products. The structure of [Ir(NC5H4-2-(Z-CHCH)-κ-N,C)(NC5H4-2-CH2CH2-κ-N,C)(NCCH3)(PiPr3)]BF4 (5), which contains two chelating ligands derived from 2-vinylpyridine, has been
determined by X-ray diffraction. The other insertion products 7−11 retain the structure of
the precursor 3 even after insertions of different regioselectivity, as evidenced by the 1-alkyne
derivatives [Ir{C(Ph)CH2}{NC5H4-2-Z-(CHCH)-κ-N,C}(NCCH3)2(PiPr3)]BF4 (9) and [Ir(E-CHCHtBu){NC5H4-2-Z-(CHCH)-κ-N,C}(NCCH3)2(PiPr3)]BF4 (10). All obtained insertion products are stable toward the reductive elimination of C−C bonds. However, derivatives
9 and 10 undergo a C−C coupling reaction to form [Ir{NC5H4-2-Z-(CHCH)-κ-N,C}{NC5H4-2-Z-(CHCH)CH(R)CH2-κ-N,C}(NCCH3)(PiPr3)]BF4 (R = Ph, 12; R = tBu, 13) after
treatment with 2-vinylpyridine excess. These latter products are isostructural, despite the
different stereochemistry of the alkenyl ligands in the precursors. Under similar conditions,
both the alkyl complex [Ir(Et){NC5H4-2-Z-(CHCH)-κ-N,C}(NCCH3)2(PiPr3)] BF4 (7) and
the diphenylacetylene derivative [Ir{Z-C(Ph)CHPh}{NC5H4-2-Z-(CHCH)-κ-N,C}(NCCH3)2(PiPr3)]BF4 (11) form the compound [Ir{NC5H4-2-Z-(CHCH)-κ-N,C}2(NCCH3)(PiPr3)]BF4
(15), after elimination of ethane and cis-stilbene, respectively. These latter observations are
discussed to conclude that the observed C−C coupling processes comprise the initial
generation of an alkene at the coordination sphere of iridium followed by the alkene insertion
into an Ir−C bond.