The trisacetonitrile complexes [IrClH(PiPr3)(NCCH3)3]BF4 (1) and [IrH2(PiPr3)(NCCH3)3]BF4 (2) have been prepared in one-pot reactions with high yields by reaction of the iridium(I) dimers [Ir(μ-Cl)(coe)2]2 and [Ir(μ-OMe)(cod)2]2 with the phosphonium salt [HPiPr3]BF4. The rates of exchange between free acetonitrile and the labile acetonitrile ligands of complexes 1 and 2 have been measured by NMR spectroscopy. This kinetic study has shown that both complexes readily dissociate one acetonitrile ligand trans to hydride, giving rise to fluxional five-coordinate intermediates. Substitution products 3−7 have been obtained by treatment of complexes 1 and 2 with CO and PMe3. The structures determined for 3−7 can be rationalized on the basis of the steric requirements of the ligands, indicating that the products are formed by thermodynamic control. Ethene inserts reversibly into the Ir−H bond of 1 to give the compound [IrCl(Et)(PiPr3)(NCCH3)3]BF4 (8), which has been used for the preparation of the stable ethyliridium(III) complexes [IrCl(Et)(PiPr3)(Py)2(NCCH3)]BF4 (9) and [Ir(η2-O2CCH3)Cl(Et)(PiPr3)(NCCH3)3] (10), respectively. The molecular structure of 10 has been determined by X-ray crystallography. The reaction of 2 with ethene, at low temperature, results in the sequential formation of the ethene complex [IrH2(η2-C2H4)(PiPr3)(NCCH3)2]BF4 (11) and the diethyl derivative [Ir(Et)2(PiPr3)(NCCH3)3]BF4 (14). At room temperature in solution, 14 undergoes reductive elimination of ethane to form the iridium(I) species [Ir(PiPr3)(NCCH3)3]BF4 (15) and [Ir(PiPr3)(η2-C2H4)(NCCH3)2]BF4 (16). These cations readily react with H2 to regenerate 2, closing a cycle for ethene hydrogenation in which several participating species have been identified. The reaction of 2 with propene in solution also allows the characterization of products of propene coordination (17) and insertion (18). In this case, the species obtained after elimination of propane are products of allylic C−H activation:  [IrH(η3-C3H5)(PiPr3)(NCCH3)2]BF4 (19) and [IrH(η3-C3H5)(η2-C3H6)(PiPr3)(NCCH3)]BF4 (20). The structure of complex 19 has been determined by X-ray diffraction, and the kinetics of dissociation of its two labile acetonitrile ligands have been studied by NMR spectroscopy. Complex 19 undergoes electrophilic activation of H2 to give propene and reform the starting complex 2.

Although mobilisation schedules and disease status influenced not only the yield of progenitor cells, but also the engraftment kinetics, the number of CD34(+) re-infused was the main predictor of haematopoietic recovery. While engraftment succeeded in most of the cases, the re-infusion of >2 x 10(6)/CD34(+)/kg resulted in significantly shorter recovery times.

The complex [IrH2(NCCH3)3(PiPr3)]BF4 (1) reacts with 2-vinylpyridine to form the hydride [IrH{NC5H4-2-Z-(CHCH)-κ-N,C}(NCCH3)2(PiPr3)]BF4 (3) in a reaction that likely involves the observed dihydride [IrH2(NC5H4-2-CHCH2-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-CHCH)-κ-N,C}(NCCH3)(PiPr3)]2(BF4)2 (4). 3 reacts with 2-vinypyridine, CH2CH2, 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-CHCH)-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-(CHCH)-κ-N,C}(NCCH3)2(PiPr3)]BF4 (9) and [Ir(E-CHCHtBu){NC5H4-2-Z-(CHCH)-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-(CHCH)-κ-N,C}{NC5H4-2-Z-(CHCH)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-(CHCH)-κ-N,C}(NCCH3)2(PiPr3)] BF4 (7) and the diphenylacetylene derivative [Ir{Z-C(Ph)CHPh}{NC5H4-2-Z-(CHCH)-κ-N,C}(NCCH3)2(PiPr3)]BF4 (11) form the compound [Ir{NC5H4-2-Z-(CHCH)-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.

Two consecutive CÀH bond activations at the coordination sphere of Ir transform the commonly employed NHC ligand IMes into the new k 3 -C fac-coordinating ligand IMes 00 . The preparation and structure of Ir(III) complexes featuring this ligand together with selected reactions toward small molecules that illustrate their reactivity keys are described.' ASSOCIATED CONTENT b S Supporting Information. Synthesis and characterization details, figures and tables on the kinetic determination, crystal data, and a CIF file for complexes 2 and 3. This material is available free of charge via the Internet at http://pubs.acs.org.