No abstract

The reactivity of the dihydrides MH 2 Cl 2 (P i Pr 3 ) 2 (M = Os (1), Ru (2)) toward allenes has been studied. Complex 1 reacts with 2 equiv of 3-methyl-1,2-butadiene and 1-methyl-1-(trimethylsilyl)allene to give 1 equiv of olefin and the π-allene derivatives OsCl 2 (η 2 -CH 2 dCdCRMe)(P i Pr 3 ) 2 (R = Me (3), Me 3 Si (4)). The X-ray structure of 4 proves the coordination to the metal center of the carbon-carbon double bond of the allene with the lowest steric hindrance. In toluene, complexes 3 and 4 are unstable and evolve into the hydride-alkenylcarbyne derivatives OsHCl 2 (tCCHdCRMe)(P i Pr 3 ) 2 (R = Me (5), Me 3 Si ( 6)). DFT calculations on the model compound OsCl 2 (η 2 -CH 2 dCdCMe 2 )(PMe 3 ) 2 (3t) suggest that the π-allene to hydride-alkenylcarbyne transformation involves the migration of both hydrogen atoms of the CH 2 group of the allene. The first of them occurs between the terminal and central carbon atoms and takes place throught the metal center. The second one is a 1,2-hydrogen shift from the allene terminal carbon to osmium. The reactions of the ruthenium complex 2 with the previously mentioned allenes give olefins and RuCl 2 (η 2 -CH 2 dCdCRMe)(P i Pr 3 ) 2 (R = Me (7), Me 3 Si ( 8)), which in dichloromethane and in the presence of allene afford the disubstituted vinylidene complexes RuCl 2 (dCdCRMe)(P i Pr 3 ) 2 (R = Me (9), Me 3 Si ( 10)). The structure of 10 in the solid state has been determined by X-ray diffraction analysis. DFT calculations show that the formation of 9 and 10 can be rationalized in terms of the initial isomerization of 7 and 8 to alkenylcarbene species, which subsequently undergo metathesis reactions with a second allene molecule.

deuterated at the heteroatom position have been catalytically prepared in 50-70% isolated yield, through H/D exchange between the D 2 molecule and the respective boranes and hydrides of the group 14 elements, in the presence of the rhodium(I)-monohydride catalyst precursor RhH{κ 3 -P,O,P-[xant(P i Pr 2 ) 2 ]} (xant(P i Pr 2 ) 2 = 9,9-dimethyl-4,5-bis(diisopropylphosphino)xanthene).

Structural Analysis of Complexes 4, 5, and 7 S3 Computational Details S5 Energies of Optimized Structures S5 UV-vis Spectra of Complexes 4-7 (Observed and Calculated) S9 Analysis of Computed UV/Vis Data for 4-7 S10 Cyclic Voltammograms of Complexes 4-7 S15 Theoretical Analysis of Molecular Orbitals of Complexes 4-7 S16 Normalized Excitation and Emission Spectra of Complexes 4-7 S25 NMR Spectra of Complexes 2-7 S29 References S42 S3 Experimental Section: General Information. All reactions were carried out with rigorous exclusion of air using Schlenk-tube techniques. Solvents were dried by the usual procedures and distilled under argon prior to use or obtained oxygen-and water-free from an MBraun solvent purification apparatus. C, H, and N analyses were carried out in a Perkin-Elmer 2400B SeriesII-Analyzer. High-resolution (HRMS) were acquired using a MicroTOF-Q hybrid quadrupole time-of-flight spectrometer (Bruker Daltonics, Bremen, Germany). MALDI-TOF mass spectra were acquired using a Bruker Autoflex III, MALDI-TOF/TOF equipped with a DCTB matrix. IR spectra were measured using a PerkinElmer Spectrum 100 FT-IR spectrometer, equipped with an ATR accessory, as pure solids. 1 H and 13 C{ 1 H} NMR spectra were recorded on a Bruker Avance 300 or 400 MHz instrument. Chemical shifts (expressed in parts per million) are referenced to residual solvent peaks. Coupling constants J are given in hertz. UV-visible spectra were registered on an Evolution 600 spectrophotomer. Steady-state photoluminescence spectra were recorded on a Jobin-Yvon Horiba Fluorolog FL-3-11 spectrofluorimeter. Lifetimes were measured using an IBH 5000F coaxial nanosecond flash lamp. Quantum yields were measured using the Hamamatsu Absolute PL Quantum Yield Measurement System C11347-11. Cyclic voltammetry measurements were performed using a Voltalab PST050 potentiostat with Pt wire as working electrode, Pt wire as counter electrode, and saturated calomel (SCE) as reference electrode. The experiments were carried out under argon in dichloromethane or acetonitrile solutions (10-3 M), with Bu 4 NPF 6 as supporting electrolyte (0.1 M). Scan rate was 100 mV s-1. The potentials were referenced to the ferrocene/ferrocenium (Fc/Fc +) couple. Preparation of [Ir(μ-Cl)(κ 2-C,N-C 6 H 4-isoqui) 2 (1). A suspension of [Ir(μ-Cl)(η 2-COE) 2 ] 2 (500 mg, 0.56 mmol) in 10 mL of 2-ethoxyethanol was treated with 1phenylisoquinoline (470 mg, 2.30 mmol) and the mixture was refluxed for 12 h. The resulting suspension was filtered and the red solid was washed with diethyl ether (3 x 10 mL). Yield: 620 mg (87%). 1 H NMR (300 MHz, CD 2 Cl 2 , 298 K): δ 9.00 (m, 4H), 8.20 (d,