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We thank the DGICYT (Projet PB 92-0092, Programa de Promocion General del Conocimiento) and European Community (Network ERBCHRXCT 930147; Project: Selective Processes and Catalysis Involving Small Molecules) for financial support. E.O. thanks the DGA (Diputacion General de Aragon) for a grant. L.R. thanks the Spanish Government for a grant (Programa de Formacion Cientifica para Iberoamerica). P.S. and H.W. acknowledge support by the Deutsche Forschungsgemeinschaft (Grant SFB 347).

The dihydrido-olefin complex OsH(2)(eta(2)-CH(2)=CHEt)(CO)(P(i)Pr(3))(2) (2) reacts with H(2)SiPh(2) to give OsH(3)(SiHPh(2))(CO)(P(i)Pr(3))(2) (3). The molecular structure of 3 has been determined by X-ray diffraction (monoclinic, space group P2(1)/c with a = 16.375(2) A, b = 11.670(1) A, c =18.806(2) A, beta = 107.67(1) degrees, and Z = 4) together with ab initio calculations on the model compound OsH(3)(SiH(3))(CO)(PH(3))(2). The coordination geometry around the osmium center can be rationalized as a heavily distorted pentagonal bipyramid with one hydrido ligand and the carbonyl group in the axial positions. The two other hydrido ligands lie in the equatorial plane, one between the phosphine ligands and the other between the SiHPh(2) group and one of the phosphine ligands. Complex 3 can also be prepared by reaction of OsH(eta(2)-H(2)BH(2))(CO)(P(i)Pr(3))(2) (4) with H(2)SiPh(2). Similarly, the treatment of 4 with HSiPh(3) affords OsH(3)(SiPh(3))(CO)(P(i)Pr(3))(2) (5), while the addition of H(3)SiPh to 4 in methanol yields OsH(3){Si(OMe)(2)Ph}(CO)(P(i)Pr(3))(2) (6). Complex 2 also reacts with HGeR(3) and HSnR(3) to give OsH(3)(GeR(3))(CO)(P(i)Pr(3))(2) (GeR(3) = GeHPh(2) (7), GePh(3) (8), GeEt(3) (9)) and OsH(3)(SnR(3))(CO)(P(i)Pr(3))(2) (R = Ph (10), (n)Bu (11)), respectively. In solution, compounds 3 and 5-11 are fluxional and display similar (1)H and (31)P{(1)H} NMR spectra, suggesting that they possess a similar arrangement of ligands around the osmium atom.

The replacement of a chloride in OsH2Cl2(P iPr3)2 (1) by a hydride, to afford OsH 3Cl(PiPr3)2 (2), produces dramatic changes in the behavior of the system. Complex 1 hydrogenates the sterically most hindered C-C double bond of gem-disubstituted allenes. In contrast, the trihydride 2 reacts with 1,1-dimethylallene and 1-methyl-1-(trimethylsilyl) allene to give the alkenyl derivates OsH2Cl{C(CH3)- C(CH3)R}(PiPr3)2 (R = CH3 (3), SiMe3 (4)), which do not undergo reductive elimination of olefin in spite of the coplanar cis disposition of the metalated carbon atom and one of the hydride ligands. The X-ray structure of 3 proves that the α-methyl substituent of the alkenyl group cancels the unsaturated character of the metal center. Complex 2 also reacts with ethyl allenecarboxylate. The reaction leads to the metallafuran OsH 2Cl{κ2C,O-[C(CH3)-CHC(O)OEt]}(P iPr3)2 (5), which has been also characterized by X-ray diffraction analysis. DFT calculations suggest that the formation of 3 and 4 is a consequence of the coplanar cisoid disposition of the hydride ligand and the CH2 group of the allene in a hydride-dihydrogen-π-allene intermediate. The DFT calculations also show that 3 and 4 are thermodynamic sinks and that the reductive elimination of the olefin is kinetically disfavored. © 2013 American Chemical Society., Financial support from the Spanish MICINN (Projects CTQ2011-23459 and Consolider Ingenio 2010 (CSD2007-00006)), the DGA (E35), and the European Social Fund (FSE) is acknowledged. We thank the Centro de Supercomputación de Galicia (CESGA) for generous allocation of computational resources.

Heterolytic B-H activation and H-H formation on an Os-SH bond give borylthiolate-dihydrogen derivatives. These species exchange borylthiol by borane to afford σ-borane derivatives or release H2 and undergo a hydride-boryl exchange to yield boryl-hydrogensulfide complexes depending on the boryl group bonded to the sulfur atom. © 2013 The Royal Society of Chemistry., Financial support from the Spanish MICINN (Projects CTQ2011-23459 and Consolider Ingenio 2010 (CSD2007-00006)), the DGA (E35), and the European Social Fund (FSE) is acknowledged. M.M. thanks the Spanish MEC for her FPU grant.

The dihydrogen complex OsCl2(η2-H2)(CO)(PiPr3) 2 (1) has been prepared by reaction of the monohydride OsHCl(CO)(PiPr3)2 (2) with HCl. Complex 1 reacts with carbon monoxide and tert-butyl isocyanide to give OsHCl-(CO)(L)(PiPr3)2 (L = CO (3), tBuNC (4)) and HCl. The reaction of 1 with phenylacetylene affords the carbene derivative OsCl2(=CHCH2Ph)(CO)(PiPr3)2 (5), which can be also obtained by reaction of Os{(E)-CH=CHPh}Cl-(CO)(PiPr3)2 (6) with HCl. The molecular structure of 5 has been determined by X-ray crystallography. Crystals of 5 are orthorhombic, space group Pbca, with unit cell dimensions a =13.641(2) Å, b =15.698(2) Å, and c = 29.059(4) Å. The structure was solved and refined using 3185 unique, observed reflections, R = 0.0412 and Rw = 0.0380. The coordination around the osmium atom can be described as a distorted octahedron with the two triisopropylphosphine ligands occupying trans positions. The PhCH2CH moiety, clearly bonded to the metal through an Os-C double bond, is situated in a relative trans position to a chloride ligand. Complex 1 reacts with 2-methyl-1-buten-3-yne to give OsCl2{=CHCH=C(CH3)2}(CO)(PiPr3) 2 (7). The reaction of 2 with 2-methyl-1-buten-3-yne leads to Os{(E)-CH=C(H)(CH3)=CH2}Cl(CO)(PiPr3) 2 (8), which gives 7 by reaction with HCl. Complex 1 also reacts with 1,7-octadiyne. The reaction produces a mixture of products from which the binuclear μ-bis-carbene compound [(PiPr3)2(CO)Cl2Os]{=CH(CH2) 6CH=}[OsCl2(CO)(PiPr3)2] (11) was identified by NMR spectroscopy. Complex 11 can be prepared as an analytically pure solid by reaction of [(PiPr3)2(CO)ClOs]{CH=CH(CH2) 4CH=CH}-[OsCl(CO)(PiPr3)2] (12) with HCl. Complex 12 was obtained from the reaction of 2 with 1,7-octadiyne., We thank the D.G.I.C.Y.T. (Project PB 92-0092, Programa de Promoción General del Conocimiento) and E.U. (Project: Selective Processes and Catalysis Involving Small Molecules) for financial support. B.Z. thanks the Ministerio de Educación y Ciencia de España (M.E.C.) and E.O. the Diputación General de Aragón (D.G.A.) for a grant.

Complex [Ir(μ-Cl)(COE)2]2 (1; COE = ciscyclooctene) reacts with Li[C5H4(CH2)2N(CH3)2 ] to give Ir{η5-C5H4(CH2)2N (CH3)2}(COE)2 (2), which affords IrI2{η5-C5,κ- N-[C5H4(CH2)2N (CH3)2]} (3), by addition of I2. The reaction of 3 with phenylacetylene yields., We thank MCYT of Spain for financial support (Projects RPQ2000-0488-94-02 and BQU2002-00606).

Catalyst (I), readily available from the imidazolium salt and Pd(O-Ac)2, is isolated as an air-stable greyish solid, which exists in solution at room temperature as a mixture of diastereomers.

Complex [OsTp(κ1-OCMe2)2(PiPr3)]BF4 (1; Tp = hydridotris(pyrazolyl)borate) reacts with 2-methylpyridine and pyridine, in acetone, at room temperature to give the N-coordinated heterocyclic derivatives [OsTp{κ1-N[NC5H4Me]}(κ1-OCMe2)(PiPr3)]BF4 (2) and [OsTp{κ1-N[NC5H5]}(κ1-OCMe2)(PiPr3)]BF4 (3). However, in fluorobenzene, at 100 °C, the reaction of 1 with 2-methylpyridine leads to the pyridylidene compound [OsTp{κ1-C[HNC5H3Me]}(κ1-OCMe2)(PiPr3)]BF4 (4). The addition of phenylacetylene and cyclohexylacetylene to the fluorobenzene solutions of the latter affords the pyridylidene-vinylidene complexes [OsTp{κ1-C[HNC5H3Me]}(═C═CHR)(PiPr3)]BF4 (R = Ph (5), Cy (6)), which undergo selective deprotonation at the Cβ atom of the vinylidene ligand to generate the alkynyl-pyridylidene derivatives OsTp(C≡CR){κ1-C[HNC5H3Me]}(PiPr3) (R = Ph (7), Cy (8)). Heating of toluene solutions of 7 and 8 at temperatures higher than 50 °C produces the hydrogen transfer from the nitrogen atom to the Cβ atom of the alkynyl ligands to afford the pyridyl-vinylidene intermediates [OsTp{κ1-C[NC5H3Me]}(═C═CHR)(PiPr3)]BF4 (R = Ph (7a), Cy (8a)), which evolve by 1,2-migratory insertion of the vinylidene ligands into the Os–pyridyl bond to give the alkenylation products OsTp{κ2-C,N[C(═CHR)C5(Me)H3N]}(PiPr3) (R = Ph (9), Cy (10)). Protonation of 9 and 10 with HBF4·EtO2 yields [OsTp{κ2-C,N[═C(CH2R)C5(Me)H3N]}(PiPr3)]BF4 (R = Ph (11), Cy (12)). Complexes 7–9 have been characterized by X-ray diffraction analysis., Financial support from the Spanish MICINN (Projects CTQ2011-23459 and Consolider Ingenio 2010 (CSD2007-00006), the DGA (E35), and the European Social Fund (FSE) is acknowledged.

The complex [Os(η 6-p-cymene)(OH)IPr]OTf (1; IPr = 1,3-bis(2,6-diisopropylphenyl)imidazolylidene; OTf = CF 3SO 3) reacts with benzonitrile and acetonitrile to afford the κ 2-amidate derivatives [Os(η 6-p-cymene) {κ 2O,N-NHC(O)R}IPr]OTf (R = Ph (2), CH 3 (3)). Their formation has been investigated by DFT calculations (B3PWP1), starting from the model intermediate [Os(η 6-benzene)(OH)(CH 3CN)IMe] + (IMe = 1,3-bis(2,6-dimethylphenyl)imidazolylidene). Complex 2 has been characterized by X-ray diffraction analysis. In the presence of water, the κ 2-amidate species release the corresponding amides and regenerate 1. In agreement with this, complex 1 has been found to be an efficient catalyst for the selective hydration of a wide range of aromatic and aliphatic nitriles to amides, including substituted benzonitriles, cyanopyridines, acetonitrile, and 2-(4-isobutylphenyl)propionitrile among others. The mechanism of the catalysis is also discussed. © 2012 American Chemical Society., Financial support from the MEC of Spain (Project numbers CTQ2011-23459 and CTQ2010-14796 and Consolider Ingenio 2010 (CSD2007-00006)) and the Diputación General de Aragón (E35) is acknowledged.

The fully CO2Me substituted aquo-iridacyclopentadiene 1 reacts with a variety of aromatic aldehydes, at 90–120 °C, with the formation of bicyclic Fischer-type carbenes, generated by the transfer of the aldehydic H atom to an α carbon of the metallacycle and concomitant bonding of the O atom to the adjacent β carbon. These carbenes have a thermodynamically favored anti configuration of these C–H and C–O bonds but it is proposed that an unobserved syn carbene is the kinetic primary product, which then easily epimerizes by adventitious water. Milder reaction conditions (25–60 °C) allow for the isolation of intermediate O-coordinated aldehyde adducts. While these reactions have been observed for a wide variety of aromatic aldehydes, 2-pyridinecarboxaldehyde behaves differently, as the reaction leads to a very stable N adduct, in spite of two isomeric O-bonded adducts being formed as kinetic products

The dihydrido-dichloro complex OsH2Cl2(P-z'-Pr3)2 (1) reacts with 2,2,-biimidazole (H2bim) to give the dihydrogen derivative [OsCl(»?2-H2)(H2bim)(P-!-Pr3)2]Cl (2). The molecular structure of 2 has been determined by X-ray investigation. 2 crystallizes with a dichloromethane molecule in the triclinic space group with a = 12.133(1)k,b = 16.034(1) A, c = 18.321(1) A, a = 105.10(1)°, ß = 90.01(1)°, y = 93.87(1)°, and Z = 4. The coordination geometry around the osmium center can be rationalized as a distorted octahedron with the two phosphine ligands disposed mutually trans. The remaining coordination sites of the octahedron are occupied by the dihydrogen ligand, the chloride atom, and by two nitrogen atoms of the chelate 2,2'-biimidazole ligand. One of the two acidic NH groups of the 2,2,-biimidazole ligand of 2 can be deprotonated by NaBH4 to give [OsCl(i)2-H2)(Hbim)(P-¡-Pr3)2] (3). Similarly the 2,2'-biimidazole ligand of 2 is deprotonated by dimers of the type [M(/u-OMe)(diolefin)]2 to form the heterobimetallic compounds [(P-i-Pr3)2(t;2-H2)C10s(/u-Hbim)RhCl(COD)] (COD = 1,5-cyclooctadiene, 4), [(P-i-Pr3)2(j)2-H2)C10s(M-Hbim)IrCl(C0D)] (5), and [(P-z-Pr3)2(r,2-H2)C10s(M-Hbim)IrCl(TFB)] (TFB = tetrafluorobenzobarrelene, 6). The addition of pyrazole to 1 leads to the complex trans-dichloro-[OsCl2(i72-H2)-(Hpz)(P-(-Pr3)2] (7), which is transformed into its isomer cis-dichloro- [OsCl2(i?2-H2)(Hpz)(P-z-Pr3)2] (8) by stirring in hexane at 60 °C. The molecular structure of 8 has also been determinated. 8 crystallizes with a pyrazole molecule in the monoclinic space group C2/c (No. 15) with a = 21.575(3) k,b = 8.743(1) A, c = 31.341(9) A, ß = 90.98(2)°, and Z = 8. The coordination geometry around the osmium center could be described as based on a distorted octahedron with the two phosphine ligands occuping the apical positions. The equatorial plane is formed by the dihydrogen and the pyrazole ligands mutually ris-disposed and the two chloride atoms are also ris-disposed., We thank Dr. E. Sola for T1 measurements and the DGICYT (Project PB 92-0092, Programa de Promoción General del Conocimiento) for financial support.

The complex [2,6-bis[(4S)-isopropyl-2-oxazolin-2-yl]pyridine]- CrCl3, prepared by reaction of CrCl3(THF)3 with 2,6-bis[(4S)- isopropyl-2-oxazolin-2-yl]pyridine, catalyses ethylene homopolymerisation and ethylene/1-hexene copolymerisation in the presence of MAO., We acknowledge financial support from the DGES of Spain (Project PB98-1591). Repsol-YPF is also acknowledged for financial support and the permission to publish these results.

The previously unnoticed Ru complex activates the title reaction which proceeds under mild conditions and is fully diastereoselective.

We report a ruthenium-catalyzed (2 + 2) intramolecular cycloaddition of allenes and alkenes. We have found that the use of the ruthenium complex RuH2Cl2(PiPr3)2, which has previously gone unnoticed in catalytic applications, is crucial for the observed reactivity. The reaction proceeds under mild conditions and is fully diastereoselective, providing a practical entry to a variety of bicyclo[3.2.0]heptane skeletons featuring cyclobutane rings. © 2011 American Chemical Society., This work was supported by the Spanish MICINN (Projects SAF2007-61015, SAF2010-20822-C02, CTQ2008-00810, and Consolider-Ingenio 2010 CSD2007-00006), CSIC, Xunta de Galicia (GRC2010/12, INCITE09 209 122 PR), Comunidad de Madrid (CCG08-CSIC/PPQ3548), Diputación General de Aragón (E35), the Marie Curie Foundation (PERG06-GA-2009- 256568), and the European Social Fund. M.G. thanks the Xunta de Galicia for a Parga Pondal Contract. A.C. thanks the CSIC for her JAE Grant.

The bis(dihydrogen) complex [OsTp(η2-H2)2(PiPr3)]BF4 (1; Tp = hydridotris(pyrazolyl)borate) reacts with ethylene under 2 atm of the gas to afford [OsTp(CH2CH2PiPr3)(η2-CH2═CH2)2]BF4 (2), which promotes the CH bond activation of fluorobenzene and 1,3-difluorobenzene to give OsTp(3-C6H4F)(η2-CH2═CH2)2 (3) and OsTp(3,5-C6H3F2)(η2-CH2═CH2)2 (4), respectively, releasing [EtPiPr3]BF4. The formation of 2 takes place via [OsTp(η2-CH2═CH2)2(PiPr3)]BF4 (5), which has been isolated and characterized by X-ray diffraction analysis., Financial support from the Spanish MICINN (Projects CTQ2008-00810 and Consolider Ingenio 2010 CSD2007- 00006), Departamento de Ciencia, Tecnología y Universidad del Gobierno de Aragón (E35), and the European Social Fund is acknowledged.

4 páginas, 1 tabla, 1 esquema., An easy and direct access to POP-type osmium(II) and osmium(IV) complexes, including OsH4{dbf(PiPr2)2} (dbf(PiPr2)2 = 4,6-bis(diisopropylphosphine)dibenzofuran), is reported. This tetrahydride derivative is an efficient catalyst for the selective formation of imines from alcohols and amines with liberation of H2, proving that osmium is a promising alternative to ruthenium for catalysis., Financial support from the MICINN of Spain (CTQ2008- 00810 and Consolider Ingenio 2010 CSD2007-00006), the Diputaci on General de Arag ón (E35), and the European Social Fund is acknowledged.

This paper shows that the redox equilibria hydride-alkenylcarbyne/alkenylcarbene and alkenyl-alkenylcarbyne/dienylcarbene are readily governed by the electronic properties of the ligands of the complexes. Because we have learned to control the position of these equilibria, we are able to build, step by step, osmium derivatives with cyclic alkenylcarbene ligands and osmacyclopentapyrrole complexes. The dihydride OsH2Cl2(PiPr3)2 reacts with alkynols, allenes, enynes, and dienes to give hydride–alkenylcarbyne derivatives, OsHCl2(CCR′CR2)(PiPr3)2, which can be transformed into dicationic species by replacement of chloride ligands by acetonitrile molecules. The selective deprotonation of the alkenylcarbyne ligand of [OsH(CCHCPh2)(CH3CN)2(PiPr3)2]2+ affords the hydride–allenylidene [OsH(CCCPh2)(CH3CN)2(PiPr3)2]+, which undergoes the reduction of the Cα–Cβ double bond of the cumulene in the presence of alcohols. The insertion of monosubstituted alkynes into the Os–H bond of the hydride–allenylidene complex leads to alkenyl–allenylidene derivatives, which are transformed into dienylcarbene compounds. The coordination of carbon monoxide to the osmium atom of the latter promotes the 4π-conrotation of the dienylcarbene ligand, to afford a cyclic alkenylcarbene complex via an η1-cyclopentadienyl intermediate. Through a similar cyclization, in acetonitrile under reflux, the alkenyl–allenylidene complexes are converted into osmapyrrole derivatives by means of the formation of three C–C bonds involving the three carbon atoms of the cumulene, the alkenyl ligand, and an acetonitrile molecule., Financial support from the MICINN of Spain (CTQ2008-00810 and Consolider Ingenio 2010 CSD2007-00006), the Diputación General de Aragón (E35), and the European Social Fund is acknowledged.

The hexahydride complex OsH6(PiPr3) 2 (1) reacts with 1-mesitylimidazole, 1-methylimidazole, 1-(2-hydroxy-2-phenylethyl)imidazole, and 1-(2-hydroxypropyl)imidazole to give the N-bound imidazole compounds OsH4(RIm)(PiPr 3)2 (R = Mes (2), Me (3), CH2CH(OH)Ph (4), CH2CH(OH)CH3 (5)) and H2. In toluene under reflux the alcohol derivatives 4 and 5 evolve into the C-bound imidazole complexes OsH3{CNHCHCHNCH=C(R)O}(PiPr3) 2 (R = Ph (6), CH3 (7)), bearing an NH wingtip. These NHC-enolate species result from the N-bound to C-bound transformation of the heterocycle and the deprotonation-dehydrogenation of the alcohol substituent. The addition of HBF4 to 6 and 7 affords the NHC-keto derivatives [OsH3{CNHCHCHNCH2C(R)=O}(PiPr3) 2]BF4 (R = Ph (8), CH3 (9)). Treatment of 1 with 3-benzyl-1-(2-hydroxy-2-phenylethyl)imidazolium tetrafluoroborate and 3-benzyl-1-(2-hydroxypropyl)imidazolium tetraphenylborate leads to the NHC-keto complexes [OsH3{CN(CH2Ph)CHCHNCH2C(R)=O}(P iPr3)2]A (A = BF4, R = Ph (10); A = BPh4, CH3 (11)), as a consequence of the direct metalation of the heterocycle and the dehydrogenation of the alcohol substituent. The deprotonation of 10 and 11 with KtBuO gives the NHC-enolate derivatives OsH3{CN(CH2Ph)CHCHNCH=C(R)O}(P iPr3)2 (R = Ph (12), CH3 (13)). The X-ray diffraction structures of 2, 6, and 10 are also reported. © 2011 American Chemical Society., Financial support from the MICINN of Spain (Project Nos. CTQ2007-65218, CTQ2008-00810, and Consolider Ingenio 2010 CSD2007-00006), the Diputación General de Aragón (E35), the Generalitat Valenciana (PROMETEO/ 2009/0349 and FEDER), and the European Social Fund is acknowledged.

The dihydride complex OsH2Cl2(PiPr 3)2 (1) reacts with 2-methyl-1-hexen-3-yne and 2,4-dimethyl-1,3-pentadiene to give the hydride alkenylcarbyne derivatives OsHCl2{≡CC(Me)=CHR}(PiPr3)2 (R = nPr (2), iPr (3)), which have been characterized by X-ray diffraction analysis. DFT calculations (B3PW91) suggest that the enyne is initially hydrogenated to afford a conjugated diene. The latter evolves into the hydride alkenylcarbyne derivative by means of two hydrogen migrations. The first migration is a 1,4-hydrogen shift within the diene (from the terminal CH2 group to the internal double bond) which takes place through the metal center. The second migration is a 1,2-hydrogen shift from the terminal CH2 group to the osmium atom. In contrast to the case for 1, the ruthenium counterpart RuH2Cl2(PiPr 3)2 (16) reacts with 2-methyl-1-hexen-3-yne to give a complex mixture of compounds, from which the derivatives Ru(η5- C5HR1R2R3R4)Cl(P iPr3) (17; R1 = C(CH3)=CH 2, R2 = Et, R3 = nPr, R4 = Me) and RuCl2{=C(Et)CH=CMe2}(PiPr 3)2 (18, traces) are isolated. Both 17 and 18 have been also characterized by X-ray diffraction analysis. DFT calculations (B3PW91) on the formation of 17 suggest that in the ruthenium case the hydrogenation of the enyne leads to an alkenylcarbene intermediate, which reacts with a second enyne molecule to afford the tetrasubstituted cyclopentadienyl group. © 2011 American Chemical Society., Financial support from the Spanish MICINN (Project numbers CTQ2008-00810 and Consolider Ingenio 2010 CSD2007-00006), the DGA (E35), and the European Social Fund is acknowledged. A.C. thanks the CSIC for her JAE grant.

Complex OsH2Cl2(PiPr3) 2 (1) reacts with 1,2-phenylenediamine in the presence of triethylamine to give OsH2(κ-N,N-o-HNC6H 4NH)(PiPr3)2 (2), containing an osmabenzimidazolium core. The planarity and length equalization of the bicycle, along with the negative NICS values calculated for both rings and the aromatic MO delocalization, suggest that, as the organic counterpart, the osmabenzimidazolium moiety of 2 is aromatic. The electron Ï€-delocalization through the bicycle has a marked influence on the chemical behavior of the metal center. Thus, in contrast to 1, complex 2 is stable in acetonitrile and reacts with [FeCp2]PF6 to give a 1:1 mixture of [OsH(κ-N,N-o-HNC6H4NH)(NCCH3)(P iPr3)2]PF6 (3) and [OsH 3(κ-N,N-o-HNC6H4NH)(PiPr 3)2]PF6 (4), containing bicycles that also appear to be aromatic. © 2011 American Chemical Society., Financial support from the MICINN of Spain (Projects CTQ2008-00810 and Consolider Ingenio 2010CSD2007-00006) and Departamento de Ciencia, Tecnología y Universidad del Gobierno de Aragón (E35) and the European Social Fund is acknowledged. M.B. thanks the Spanish MICINN/Universidad de Zaragoza for funding through the “Ramón y Cajal” Program.

3 páginas, 2 figuras, 2 tablas.-- et al., The title compound, [W(C5H5)(HOBF3)(CO)3], has a four-legged piano-stool geometry which is typically found for C5H5W(CO)3X complexes. The HOBF3- anion is the hydrolysis product of BF4- and is coordinated via oxygen., ECS thanks the EU for an Erasmus grant. EOR is grateful for financial support from the Spanish MICINN (project No. CTQ2008-00810 and Consolider Ingenio 2010 CSD2007- 00006).

5 páginas, 1 figura, 1 esquema, 1 tabla., The reactions of (2-pyridyl)methylenecyclobutane with the metal fragments [OsTp(PiPr3)]þ and [OsCp(PiPr3)]þ (Tp = hydridotris(pyrazolyl)borate, Cp = cyclopentadienyl) are shown. Complex [OsTp(κ1-OCMe2)2(PiPr3)]BF4 (1) reacts with the organic substrate to give [OsTp{η2-C(CH2CH2CH2)dCH-C5H4N}(PiPr3)]BF4 (2), which evolves into the cyclopentylidene derivative [OsTp(dCCH2CH2CH2CH-C5H4N)(PiPr3)]BF4 (3) as a result of the ring expansion of the methylenecyclobutane unit of the coordinated substrate. The reaction of (2-pyridyl)methylenecyclobutane with [OsCp(NCCH3)2(PiPr3)]PF6 (4) leads to [OsCp{η2-C(CH2CH2CH2)dCH-C5H4N}-(PiPr3)]PF6 (5). In contrast to 2, complex 5 evolves by means of exo-endo isomerization of the C-C doublebondof the coordinated substrate toafford [OsCp{η2-C(dCHCH2CH2)-CH2-C5H4N}(PiPr3)]PF6 (6)., Financial support from the Spanish MICINN (Projects CTQ2008-00810 and Consolider Ingenio 2010 (CSD2007-00006)) and the Diputación General de Aragón (E35) is acknowledged.

The reactivity of the dihydrides MH2Cl2(P iPr3)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 OsCl2(η2-CH2=C=CRMe)(P iPr3)2 (R = Me (3), Me3Si (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 OsHCl2(≡CCH=CRMe)(P iPr3)2 (R = Me (5), Me3Si (6)). DFT calculations on the model compound OsCl2(η2-CH 2=C=CMe2)(PMe3)2 (3t) suggest that the π-allene to hydride-alkenylcarbyne transformation involves the migration of both hydrogen atoms of the CH2 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 RuCl2(η 2-CH2=C=CRMe)(PiPr3)2 (R = Me (7), Me3Si (8)), which in dichloromethane and in the presence of allene afford the disubstituted vinylidene complexes RuCl2(=C=CRMe) (PiPr3)2 (R = Me (9), Me3Si (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. © 2010 American Chemical Society., Financial support from the Spanish MICINN (projects CTQ2008-00810 and Consolider Ingenio 2010 CSD2007-00006) and the DGA (E35) is acknowledged. A.C. thanks the CSIC for her JAE grant.

2 páginas, 1 figura, 2 esquemas., The complex [OsTp(κ1-OCMe)2(PiPr3)]BF4 [Tp = hydridotris(pyrazolyl)borate] promotes the cleavage of both C(sp3)−C(sp2) bonds of benzylidenecyclopropane and 3-phenylpropylidenecyclopropane to yield the complexes [OsTp(═C═CHR)(η2-CH2═CH2)(PiPr3)]BF4 (R = Ph, CH2CH2Ph). The process is proposed to take place via metallacyclopropene intermediates stabilized by an ethylene chelation assistant. The driving force for the fragmentation is the high stability of the resulting ethylene−Os−vinylidene species., Financial support was provided by the Spanish MICINN [Projects CTQ2008-00810, SAF2007-61015, and Consolider Ingenio 2010 (CSD2007-00006)], Diputacio´n General de Arago´n (E35), and Xunta de Galicia (GRC2006/132). L.S. and L.V. thank MICINN and Xunta de Galicia for their grants.

Financial support from the MICINN of Spain (Projects CTQ2008-00810 and Consolider Ingenio 2010 CSD2007-00006), Diputación General de Aragón (E35), and the European SocialFund is acknowledged.M.B. thanks the Spanish MICINN/Universidad de Zaragoza for funding through the “Ramón y Cajal” program.

The complex OsH2Cl2(PiPr3)2 reacts with pinacolborane, Me2NH−BH3, and tBuNH2−BH3 to give the complexes OsH2Cl{η2-HBOC(CH3)2C(CH3)2OBpin}(PiPr3)2 and OsH2Cl(η2-HBNR1R2)(PiPr3)2 (R1 = R2 = Me; R1 = H, R2 = tBu) containing monosubstituted alkoxy- and amidoborinium cations coordinated as σ-B−H ligands. The process is proposed to take place via the electrophilic 14-valence-electron fragment OsHCl(PiPr3)2, which promotes hydride transfer from the corresponding borane to the osmium atom., Financial support from the Spanish MICINN [Projects CTQ2008-00810, Consolider Ingenio 2010 (CSD2007- 00006), and FR2009-0024] and Diputación General de Aragón (E35) is acknowledged.

Complexes [MCl2(η6-p-cymene)]2 (M = Os (1a), Ru (1b)) react with Li(C5H4CH2CH2NHMe) (LiCpN) and KPF6 to give the sandwich derivatives [M(η5-CpN)(η6-p-cymene)]PF6 (M = Os (2a), Ru (2b)). Treatment of 2a and 2b with (2,2′-biphenol)PCl leads to [M(η5-CpP)(η6-p-cymene)]PF6 (M = Os (3a), Ru (3b); CpP = C5H4CH2CH2N(Me)P(2,2′-biphenol)). The photolysis of 2a, 2b, 3a, and 3b in acetonitrile produces the release of the p-cymene group and the coordination of the cyclopentadienyl pendant substituent to the metal center to afford [M(η5-C5,κ-N-CpN)(CH3CN)2]PF6 (M = Os (4a), Ru (4b)) and [M(η5-C5,κ-P-CpP)(CH3CN)2]PF6 (M = Os (5a), Ru (5b)). Complex 4a, which has been characterized by X-ray diffraction analysis, is a more efficient catalyst precursor than 4b for the redox isomerization of primary allylic alcohols, while the latter is more efficient than the former for the redox isomerization of secondary allylic alcohols. From the catalytic solutions containing 4a and 2-methyl-2-propen-1-ol, the η3-1-hydroxyallyl complex [OsH(η5-C5,κ-N-CpN){η3-CH2C(CH3)CHOH}]PF6 (6) has been crystallized and characterized by spectroscopic methods and X-ray diffraction analysis. The structure shows a N−H···O hydrogen bond (2.22 ºA) between the NH-hydrogen atom of the coordinated pendant amine group and the oxygen atom of the hydroxy substituent of the allyl ligand., Financial support from the Spanish MICINN (Projects CTQ2008-00810 and Consolider Ingenio 2010 CDS2007-00006) and the DGA (E35) is acknowledged. C.G.-Y. thanks the Spanish MEC and the University of Zaragoza for funding through the “Ramón y Cajal” program. M.B. thanks the Spanish MICINN for a predoctoral fellowship.

The reactions of the hexahydride complex OsH6(P iPr3)2 (1) with 4,5-dimethyl-2,6-bis(4- methylphenyl)pyrimidine (H2Ll), 2,4,6-tris-(4-methylphenyl)-l,3,5- triazine (H4L2), and 2,4,6-triphenylpyrimidine (H4L3) have been studied. Complex 1 reacts with H2Ll to give a mixture of the metallapolycyclic derivatives OsH3(HLI)(PiPr 3J2 (2) and OsH2(L1)(PiPr 3)2 (3). Compound 2 arises from the coordination of the N3-pyrimidine nitrogen atom to osmium and the ortho-CH bond activation of the C2-bonded phenyl group. The formation of 3 involves the coordination of the N1-pyrimidine nitrogen atom to osmium and the ortho-CH bond activation of both phenyl groups. The reaction of 1 with H4L2 leads to a mixture of OsH2(H2L2)(PiPr3)2 (4) and (P'Pr3)2H2Os(L2)OsH2(PiPr 3)2 (5), containing five and eight fused rings, respectively. Complex 4 results from the coordination of the N1-triazine nitrogen atom to osmium and the ortho-CH bond activation of the phenyl groups at positions 2 and 6 of the triazine ring. Complex 5 results from the coordination of the N1 and N3 of triazine to two different metal centers along with a double ortho-CH bond activation in each proximal phenyl group. Complex 1 reacts with H4L3 to afford OsH2(H2L3)(PiPr 3)2 (6) and (PiPr3) 2H2Os(L3)OsH2(PiPr3) 2 (7), which are related to 4 and 5, respectively. Complexes 2,3,4, and 5 have been characterized by X-ray diffraction analysis. The structures prove the planarity of their cores and suggest electron derealization through the polycyclic system. Quantum chemical calculations (DFT level) on model compounds clearly indicate that the Os-C and Os-N bonds of the newly formed metallapolycycles exhibit a remarkable double-bond character that is higher for the Os-C bond, in very good agreement with the experimental findings. © 2010 American Chemical Society., Financial support from the MICINN of Spain (project numbers CTQ2008-00810, CTQ2007-67730-C02-01/BQU, and Consolider Ingenio 2010 CSD2007-00006), the Diputación General deAragón (E35), and the CAMCCG07-UCM/PPQ-2596 is acknowledged. I.F. is a Ramón y Cajal Fellow. M. M.-O. thanks the MICINN for a FPI predoctoral grant.

7 páginas, 3 figuras, 5 esquemas., Complex [Os(═CHPh)(CH3CN)4(IPr)](OTf)2 (1) (IPr = 1,3-bis(2,6-diisopropylphenyl)imidazolylidene; OTf = CF3SO3) exchanges the alkylidene group with propylene to give styrene and [Os(═CHCH3)(CH3CN)4(IPr)](OTf)2 (2). The reaction of 1 with ethylene leads to [Os(η2-CH2═CH2)(CH3CN)4(IPr)](OTf)2 (3) via the propylene intermediate [Os(η2-CH2═CHCH3)(CH3CN)4(IPr)](OTf)2 (4). Acetonitrile displaces the olefin ligand of both 3 and 4 to generate the pentakis (solvento) derivative [Os(CH3CN)5(IPr)](OTf)2 (5). In 2-propanol and methanol, complex 5 reacts with 1,1-diphenyl-2-propyn-1-ol and 2-methyl-3-butyn-2-ol to yield the corresponding alkoxyalkenylcarbene compounds [Os{═C(OR)CH═CR′2}(CH3CN)4(IPr)](OTf)2 (R = CH(CH3)2; R′ = Ph (6), CH3 (7); R = CH3; R′ = Ph (8), CH3 (9)). The X-ray structures of 4, 5, and 6 are also reported.

The neutral rhodium(III) complex [Rh(C5Me5)I{PO(OMe)2}{P(OH)(OMe)2}] reacts with pyrazole-type ligands [HL = pyrazole (Hpz), 3-methylpyrazole, or 3,5-dimethylpyrazole] in the presence of AgClO4 yielding cationic complexes of the general formula [Rh(C5Me5){PO(OMe)2}{P(OH)(OMe)2}(HL)]ClO4. They react with Na2CO3 in aqueous solutions with formation of the neutral complexes [Rh(C5Me5){PO(OMe)2}2(HL)]. Addition of NaH in tetrahydrofuran to the cationic complexes or thallium acetylacetonate in MeOH to the neutral compounds affords the corresponding bimetallic derivatives [(C5Me5)Rh{PO(OMe)2}2LM](M = Na or Tl). These complexes react with halide compounds such as [{M(ring)Cl2}2][M(ring)= Rh(C5Me5), Ir(C5Me5), Ru(C6H6), Ru(C6H5Me), Ru(MeC6H4Pri-p) or Ru(C6Me6)], [MBr(CO)5], [(PtMe3I)4] or [{Rh(µ–Cl)(cod)}2](cod = cycloocta-1,5-diene) to give cationic or netural complexes of the type [(C5Me5)Rh{µ-PO(OMe)2}2(µ-L)-M(ring)]ClO4 or [(C5Me5)Rh{PO(OMe)2}2(µ-L)MLn][MLn= Re(CO)3, Mn(CO)3, PtMe3 or Rh(cod)]. The crystal structure of [(C5Me5)Rh{µ-PO(OMe)2}2(µ-pz)Ru(C6H6)]ClO4·CH2Cl2 has been determined by X-ray diffraction methods: monoclinic, space group P21/c, a= 11.179(1), b= 17.039(1), c= 18.186(2)A, β= 94.85(1)° and Z= 4. The complex cation consists of one rhodium and one ruthenium atom bridged by two phosphonate and one pyrazolate anion. An η5-C5Me5 and an η6-C6Me6 group complete the co-ordination spheres of the metals, which show no direct intermetallic interaction.

The seven-coordinate osmium(IV) dihydride cation [OsH2(κ2-O2CCH3)(H2O)(PiPr3)2]BF4 reacts with ethylene to give the tetraethylene dimer complex [{(PiPr3)(η2-C2H4)2Os}2(μ-OH)2(μ-O2CCH3)]BF4, which h...

Alkylidenecyclopropanes containing a chelation assistant at the terminal carbon atom of the olefinic moiety undergo an Os- or Ru-promoted ring expansion reaction to afford metal cyclobutylidene derivatives. The process occurs through a novel mechanism that implies a 1,2-migration of a CH2 group of the three-membered ring from an olefinic carbon atom to the other one. It takes place, without direct participation of the metal, on a metallaheterocyclopentene intermediate which is generated from an η2-methylenecyclopropane species stabilized by coordination of the chelation assistant., Financial support from the Spanish MICINN (Projects CTQ2008-00810, SAF2007-61015 and Consolider Ingenio 2010 (CSD2007-00006)), Diputacin General de Aragón (E35), and Xunta de Galicia (GRC2006/132). L.S. and L.B. thank MICINN and Xunta de Galicia for their grants.

The complex [OsH(=C=C=CPh2)(CH,CN)2(PiPr 3)2]BF4 (1) reacts with 2-methyl-l-buten-3-yne to give [Os{(E))-CH=CHC(CH3)=CH2}(=C=C=CPh2)(CH3CN) 2(PiPr3)2]BF4 (2). Treatment of 2 with HBF4 leads to the alkenylcarbene-allenylidene derivative [Os{=CHCH=C(CH3)2}(=C=C=CPh2) (CH 3CN)2(PiPr3)2][BF4] 2 (3). In contrast to its reaction with HBF4, the reactions of 2 with acetic acid, acetylacetone, and acetoneoxime afford thebutadienyl - alkenylcarbynespecies[Os{(E)-CH=CHC(CH3)=CH 2}(κ2-O2CCH3)(=CCH=CPh 2)(PiPr3)2]BF4 (4), [Os{(E)-CH=CHC(CH3)=CH2}κ2O,O, -acac)(=CCH=CPh2)(PiPr3)2] 4 (5), and [Os{(E)-CH=CHC(CH3)=CH2} {κ;+2,0- [ON=C(CH3)2]}(=CCH=CPh 2)(PiPr3)2]BF4 (6), respectively. The X-ray structures of 4 and 6 are also reported. © 2009 American Chemical Society., Financial support from the Spanish MICINN (Projects CTQ2008-00810 and Consolider Ingenio 2010 CSD2007-00006) and the DGA (E35) is acknowledged. A.C. thanks the CSIC for her JAE grant.

The behavior of OsH2Cl2(PiPr 3)2 (1) in acetonitrile as solvent is studied. Acetonitrile coordinates to the metal center of 1 and promotes the dihydride - dihydrogen transformation of its OsH2 unit to give the trans-Cl 2 compound OsCl2(η2-H2)(CH 2CN)(PiPr3)2 (2a), which evolves to its cis-Cl2 isomer 2b. Treatment of 1 with TIPF6 in acetonitrile leads to the PF6 salt of the cis-bis(acetonitrile) cation [OsCl(η2-H2)(CH3CN) 2-(PiPr3)2]+ (3a), which is transformed into its trans-bis(acetonitrile) isomer 3b. The addition of Et3N to the PF6 salts of 3a,b in acetonitrile gives [OsH(CH3CN)3(PiPr3) 2]PF6 (4). Reaction of 4 with 1,5-cyclooctadiene (COD) in refluxing toluene affords [OsH(COD)(CH3CN)2(P iPr2)]PF6 (5). The X-ray structures of 3b and 5 are also reported. © 2009 American Chemical Society., Financial support from the MICINN of Spain (Project No. CTQ2008-00810 and Consolider Ingenio 2010 CSD2007-00006) and the Diputación General de Aragón (E35) is acknowledged.

[TpRuCl(PTA)(PPh3)] (1; PTA = l,3,5-triaza-7-phosphaadamantane) reacts with phenylacetylene, yielding the alkynyl complex [TpRu(C≡CPh) (PTA)(PPh3)] (2) or the neutral vinylidene complex [TpRuCl{C=C(H)Ph}(PTA)] (4), depending on the solvent and the reaction conditions (Tp = hydrotris(pyrazolyl)borate). Protonation of 2 with HOTf(OTf = OSO2CF3) in CH2Cl2 yields the dicationic vinylidene compound [TpRu{C=C(H)Ph}{PTAH}(PPh3)](OTf) 2 (3), bearing a N-protonated PTA ligand. Reaction of 1 with 1,1-diphenyl-2-propyn-l-ol affords the new cationic compound [TpRu(C=C=CPh 2)(PTA)(PPh3)]PF6 (5) or neutral allenylidene compound [TpRuCl(C=C = CPh2)(PTA)] (6), depending on the reaction solvent (MeOH or toluene, respectively). The reactivity of complexes 5 and 6 toward tertiary phosphines (PTA and PPh2Me) has been investigated. Remarkably, both the cationic and the neutral allenylidene compounds undergo regioselective nucleophilic attack at the allenylidene Ca position to give the cr-allenyl-phosphonium complexes [TpRu{C(L)=C=CPh2}(PTA)(PPh 3)]PF6 (L = PPh2Me (8), PTA (9)) and [TpRuCl{C(L)= C=CPh2)(PTA)] (L = PTA (10), PPh2Me (11)), respectively. Noticeably, the reaction goes to completion in the case of the neutral allenylidene complex 6, whereas an equilibrium between the phosphonioallenyl adduct and the educt species is observed in the case of the cationic allenylidene compound 5. The thermodynamic parameters for such an equilibrium have been determined by NMR methods at different temperatures. Finally, the hydrolysis of the neutral allenylidene 6 has been briefly considered, showing the formation of the carbonyl compound [TpRuCl(CO)(PTA)] (7). © 2009 American Chemical Society., We obtained financial support from the Xunta de Galicia (Project CITE08PXIB314206PR) and the Spanish MCINN (Project Consolider Ingenio CSD2007-00006).

Complex [(η6-p-cymene)OsCl(IPr)]OTf (1; IPr = 1,3-bis(2,6-diisopropylphenyl)imidazolylidene; OTf = CF3SO3) reacts with NaOH to give [(η6-p-cymene)Os(OH)(IPr)]OTf (2), which under hydrogen atmosphere affords [(η6-p-cymene)OsH3(IPr)]OTf (3). The hydride ligands of 3 undergo exchange coupling, decreasing the H−H coupling constant from 206 to 74 Hz in the temperature range 213−178 K. Complex 3 is also obtained in a two-step procedure involving the reaction of 2 with NaBH4 to give (η6-p-cymene)OsH2(IPr) (4) and the protonation of the latter with HOTf. Attempts to obtain 4 directly from 1 or (η6-p-cymene)OsCl2(IPr) (5) are unsuccessful. In both reactions (η6-p-cymene)OsHCl(IPr) (6) is formed. Complex 2 also reacts with methanol and 2-propanol. At −30 °C, the reaction with the first of them leads to [(η6-p-cymene)Os(OMe)(IPr)]OTf (7), while with the second one, [(η6-p-cymene)OsH{κ1-OC(CH3)2}(IPr)]OTf (8) is obtained. Complex 2 is a catalyst precursor for the hydrogen transfer from 2-propanol to aldehydes, which ...

Complex [H(EtOH)2][{OsCl(η4-COD)}2(μ-H)(μ-Cl)2] (1) reacts with 1-hexene, acetone, and acetophenone to give the corresponding reduced organic substrates and the osmium polymer [OsCl2(COD)]x (2, COD = 1,5-cyclooctadiene), which regenerates 1 in ethanol. The reaction of 2 with acetonitrile leads to the mononuclear derivative OsCl2(η4-COD)(CH3CN)2 (3). On the other hand, treatment of 1 with acetonitrile affords the neutral dimer {Os(CH3CN)(η4-COD)}(μ-H)(μ-Cl)2{OsCl(η4-COD)} (4), which has been characterized by X-ray diffraction analysis. The reaction of 4 with triisopropylphosphine gives {Os(Pi-Pr3)(η4-COD)}(μ-H)(μ-Cl)2{OsCl(η4-COD)} (5). Complex 1 is an active catalyst for the ionic hydrogenation of aldehydes and ketones, using 2-propanol as hydrogen source. The reductions of aromatic compounds are easier than those of aliphatic ones, and the hydrogenations of aldehydes are also easier than those of ketones. Complex 1 also promotes the alcohol etherification and one-pot synthesis of isopropyl ethers starting from 2-propanol and the corresponding aldehyde or ketone through catalytic hydrogenation−etherification tandem processes., Financial support from the MEC of Spain (Proyect CTQ2005-00656) and Consolider Ingenio 2010 (CDS2007-00006) is acknowledged. C.G.-Y. thanks the Spanish MEC and the University of Zaragoza for funding through the “Ramón y Cajal” program.

Complex [OsH(η2-H2)(η2-CH 2=CH-o-C5H4N)(PiPr3) 2]BF4 (1) reacts with methyl vinyl ketone in the absence of solvent to give [OsH{CHCHC(O)CH3}2(PiPr 3)2]BF4 (2), which can be described as two osmafurans joined by a common [OsH(PiPr3) 2]+ fragment. The hydride ligand of 2 is fairly acidic. Thus, its treatment with sodium methoxide produces the deprotonation of the metal center to give Os{CHCHC(O)CH3}2(PiPr 3)2 (3). The reaction is not reversible; the protonation of 3 with HBF4·OEt2 leads to [Os{CHCHC(O)CH 3} {=CHCH2C(=O)CH3} (PiPr 3)2]BF4 (4), which in dichloromethane is unstable and evolves into [Os{CHCHC(O)CH3} Cl{≡CCH=C(CH 3)OH} (PiPr3)2]BF4 (5), containing an enolcarbyne ligand. In the solid state the anion of 5 is associated with the OH-hydrogen of the enol, by means of an H⋯F hydrogen bond. In dichloromethane the H⋯F hydrogen bond is broken and DFT calculations suggest that the OH-hydrogen atom forms an H⋯Cl hydrogen bond with the chlorine ligand. In the absence of solvent, complex 1 reacts with benzylideneacetophenone and benzylideneacetone to give [Os{C(Ph)CHC(O)R} (η2-H2){κ-C-[HNC5H3Et]} (PiPr3)2]BF4 (R = Ph (6), CH 3 (10)), containing a NH-tautomerized 2-ethylpyridine ligand. Complexes [Os{C(Ph)CHC(O)R}(η2-H2){ (CH 3CN)}(PiPr3)2]BF4 (R = Ph (8), CH3 (H)) and [Os{C6H4C(O)CH=CHPh (η2-H2) {(CH3CN)}(PiPr 3)2]BF4 (9) have been also isolated and characterized. The X-ray structures of 2, 5, and 6 are reported. © 2008 American Chemical Society., Financial support from the MEC of Spain (project number CTQ2005-00656 and Consolider Ingenio 2010 CSD2007-00006) and the Diputación General de Aragón (E35) is acknowledged. K.G. thanks the Spanish MEC and the European Social Fund for her grant.

Complexes MH2Cl2(PiPr3) 2 (M = Os (1), Ru (1a)) promote the NH-tautomerization of 2-methylpyridine and stabilize the resulting NH-tautomer to afford the dihydrogen derivatives MCl2(η2-H2) {κ-C[HNC5H3Me] }(PiPr3) 2 (M = Os (2), Ru (3)), containing the heterocycle coordinated by the Cα atom. In dichloromethane under reflux, complex 3 loses the coordinated hydrogen molecule to give the five-coordinate derivative RuCl 2{κ-C-[HNC5H3Me])(PPr3) 2 (4). In contrast to 2-methylpyridine, the reactions of 1 and la with pyridine lead to MCl2(κ-N-[NC5H 5]})3(PiPr3) (M = Os (5), Ru (5a)), containing the heterocycle coordinated by the lone pair of the nitrogen. DFT calculations using PMe3 as a model of PPr3 show that the formation of 2 and the related quinoline complex OsCl2(η 2-H2){κ-C-[HNC9H6]}(P iPr3)2 (6) involves an intermolecular osmium to nitrogen hydrogen migration, the subsequent Cα-H bond activation of the protonated heterocycle, and the dihydride-dihydrogen tautomerization of the resulting dihydride. The structures of 2 and 5 have been determined by X-ray diffraction analysis. © 2008 American Chemical Society., Financial support from the MICINN of Spain (project number CTQ2005-00656 and Consolider Ingenio 2010 CSD2007-00006) and the Diputación General de Aragón (E35) is acknowledged. F.J.F.-A. thanks the CSIC and the European Social Fund for funding through the I3P Program.

Complex [(η6-p-cymene)OsCl(IPr)]OTf (1; IPr = 1,3-bis(2,6-diisopropylphenyl)imidazolylidene; OTf = CF3SO 3) reacts with NaOH to give [(η6-p-cymene)Os(OH)(IPr)] OTf (2), which under hydrogen atmosphere affords [(η-p-cymene)OsH 3(IPr)]OTf (3). The hydride ligands of 3 undergo exchange coupling, decreasing the H-H coupling constant from 206 to 74 Hz in the temperature range 213-178 K. Complex 3 is also obtained in a two-step procedure involving the reaction of 2 with NaBH4 to give (η6-p-cymene)OsH 2(rPr) (4) and the protonation of the latter with HOTf. Attempts to obtain 4 directly from 1 or (η6-p-cymene)OsCl2(IPr) (5) are unsuccessful. In both reactions (η6-η-cymene) OsHCl(rPr) (6) is formed. Complex 2 also reacts with methanol and 2-propanol. At -30 °C, the reaction with the first of them leads to [(η6-p- cymene)Os(OMe)(IPr)]OTf (7), while with the second one, [(η6-p- cymene)OsH{κ;1-OC(CH3)2J(IPr)]OTf (8) is obtained. Complex 2 is a catalyst precursor for the hydrogen transfer from 2-propanol to aldehydes, which does not need a base. The obtained TOF values are between 950 and 3500 h_1. The X-ray structures of 2 and 6 are also reported. © 2008 American Chemical Society., Financial support from the MEC of Spain (project number CTQ2005-00656 and Consolider Ingenio 2010 CSD2007-00006) and the Diputación General de Aragón (E35) is acknowledged. R.C. thanks the CSIC and the Spanish MEC for funding through the “Ramón y Cajal” Program.

The dihydrogen complex [OsTp(η2-H2) (κ1-OCMe2)(PiPr3)]BF 4 (1; Tp = hydridotris(pyrazolyl)borate) reacts with tert-butylacetylene to give the hydride-carbyne derivative [OsHTp(≡ CCH2 tBu)(PiPr3)]BF4 (2). Similarly, the treatment of 1 with (trimethylsilyl)acetylene in the presence of methanol leads to [OsHTp(≡CCH3)(PiPr 3)]BF4 (3). In chloroform at 60°C, complexes 2 and 3 evolve into the corresponding chloro derivatives [OsClTp(≡CR)(P iPr3)]BF4 (R = CH2 tBu (4), CH3 (5)), whereas in acetonitrile the carbenes [OsTPi=CHR)(NCCH3)(PiPr3)]BF4 (R = CH2 tBu (6), CH3 (7)) are formed. Complex 1 also reacts with phenylacetylene. The reaction initially gives [OsHTp(≡ CCH2Ph)(PiPr3)]BF4 (8). Subsequently, the insertion of a second molecule of alkyne into the Os-H bond of 8 and the migration of the resulting alkenyl group from the metal center to the carbyne carbon atom take place, to afford the carbene [OsTp{=C(CH 2Ph)C(Ph)=CH2}(PiPr3)]BF 4 (9). The metal center of 9 is saturated by means of a strong agostic interaction (rbp = 0.4(1)) between the osmium atom and one of the ortho-CH bonds of the phenyl substituent of the alkenyl unit of the alkenylcarbene ligand. Treatment of 1 with methylpropiolate leads to the carbene [OsTp {=CHCH2C(O)OMe} (PiPr3)]BF4 (10) in a one-pot synthesis. Complexes 2, 4, 9, and 10 have been characterized by X-ray diffraction analysis. © 2008 American Chemical Society., Financial support from the MEC of Spain (Projects CTQ2005-00656 and Consolider Ingenio 2010 CSD2007-00006) and Diputación General de Aragón (E35) is acknowledged.

Complex [OsCl2(η6-p-cymene)]2 (1) reacts with (5,7-dioxa-6-phosphadibenzo[a,c]cyclohepten-6-yl)-dimethylamine (L1) and (-)-(R)-(3,5-dioxa-4-phosphacyclohepta[2,1-a;3,4-a′] dinaphthalen-4-yl)di-methylamine (L2) to give OsCl 2(η6-p-cymene)L (L = L1 (2), L2 (3)). Complexes 1-3 and OsCl2(η6-p-cymene){P(OPh) 3} (4) are efficient catalyst precursors for the alkylation of 1-phenylallyl methylcarbonate (5a), 1-phenylallyl acetate (5b), cinnamyl methylcarbonate (6a), and cinnamyl acetate (6b) with sodium dimethylmalonate to afford 1-phenylallyl dimethylmalonate (7) and cinnamyl dimethylmalonate (8) with branchedrlinear molar ratios between 97:3 and 67:33. In the absence of sodium dimethylmalonate, the reaction of 1 with 5a leads initially to {OsCl(η6-p-cymene)}2(ο-OMe)2 (9) and subsequently to [{Os(η6-p-cymene)}2(ο-OMe) 3][O2COMe] (10). In the absence of 5a, the reaction of 1 with sodium dimethylmalonate gives Os{k1-C3-[CH(CO 2Me)2]}{k2-O,O-[CH(CO2Me) 2]}(η6-p-cymene) (11). Complexes 9-11 are also efficient catalyst precursors for the alkylation of 5a with sodium dimethylmalonate. The activity of 9 and 10 is the same as that of 1. However, complex 11 is significantly less efficient than 1. In contrast to the latter, complexes 2 and 3 do not react with 5a in the absence of sodium dimethylmalonate. In the absence of the substrate, the reactions of 2 and 3 with sodium dimethylmalonate lead to OS{k1-C3-[CH(CO 2Me)2]}Cl(η6-p-cymene)L (L = L1 (12), L2 (13)), which further react with excess sodium dimethylmalonate to give 11. The catalytic behavior of 12 and 13 has been also studied. Their activities are the same as those of 2 and 3 and intermediate between those of 10 and 11. Complexes 3, 9, 11, and 12 have been characterized by X-ray diffraction analysis. © 2008 American Chemical Society., Financial support from the MEC of Spain (Proyect CTQ2005-00656) and Consolider Ingenio 2010 (CSD2007-00006) is acknowledged. C.G.-Y. thanks the Spanish MEC and the University of Zaragoza for funding through the “Ramón y Cajal” program.

The styryl-allenylidene complex [Os{(E)-CH=CHPh}(=C=C=CPh 2)(CH3CN)2(PiPr3) 2]BF4 (2) reacts with HBF4 to give the styryl-alkenylcarbyne [Os{(E)-CH=CHPh}(=CCH= CPh2)(CH 3CN)2(PiPr3)2](BF 4)2 (3), which in acetonitrile evolves into the dienylcarbene derivative [Os{=C[(E)-CH=CHPh]CH=CPh2](CH 3CN)3(PiPr3)2](BF 4)2 (4) by means of the concerted migration of the styryl ligand from the metal center to the carbyne Cα. atom. A kinetic study and DFT calculations on the transformation of 3 into 4 are reported. © 2008 American Chemical Society., Financial support from the MICINN of Spain (project number CTQ2005-00656 and Consolider Ingenio 2010 CSD2007-00006) and the Diputación General de Aragón (E35) is acknowledged. R.C. thanks the CSIC and the Spanish MICINN for funding through the “Ramón y Cajal” Program.

Aromatic diosmatricyclic nitrogen-containing compounds are prepared from Os(VI) complex OsH6(PiPr3) by double 1,3-C-H bond activation of aromatic six-membered cycles with imino substituents meta disposed. Copyright © 2008 American Chemical Society., Financial support from the Spanish MEC (Projects CTQ2005-00656 and Consolider Ingenio 2010 (CSD2007-00006)) and Diputación General de Aragón (E35).

13 pages, 1 table, 13 figures, 4 schemes.-- Supporting Information Available: http://pubs.acs.org., The hexahydride complex OsH6(PiPr3)2 (1) reacts with 8-methylquinoline and 2-(dimethylamino)pyridine to give OsH3(CH2C9H6N)(PiPr3)2 (2) and OsH3{CH2N(CH3)-o-C5H4N}(PiPr3)2 (3), respectively, as a result of the release of two hydrogen molecules of 1 and the C(sp3)-H bond activation of a methyl group of the organic substrates. In solution the hydride ligands and the hydrogen atoms of the methylene group of 2 exchange their positions. The activation parameters for the process are ¢Hq ) 18.9 ( 0.1 kcalâmol-1 and ¢Sq ) 3 ( 2 eu. Treatment of 2 with HBF4 affords the hydride-elongated dihydrogen derivative [OsH(è2-H2)(CH3C9H6N)(PiPr3)2]BF4 (6), with the methyl group of the quinoline ligand coordinated in a è3-H2C fashion. The X-ray structure of 6 and the DFT optimization of the structure of the model cation [OsH(è2-H2)(CH4)(NH3)(PMe3)2]+ prove that the methyl coordination in the ä agostic complex is similar to the methane coordination in the model compound. The reaction of 3 with HBF4 leads to the cyclic carbene derivative [OsH3{dCHN(CH3)-o-C5H4N}(PiPr3)2]BF4 (7), as a result of the release of a hydrogen molecule and a C(sp3)-H bond activation on the methylene group of 3. The formation of 2, 3, 6, and 7 has been analyzed by DFT calculations., Financial support from the MEC of Spain (Projects CTQ2005-00656, CTQ2005-9000-C02-01, and Consolider Ingenio 2010 CSD2007-00006) is gratefully acknowledged. B.E. thanks the Spanish MEC for her grant. M.B. thanks the Spanish MEC/Universidad de Zaragoza for funding through the “Ramón y Cajal” program.

2 pages, 1 scheme.-- Supporting Information Available: http://pubs.acs.org., Reaction of [OsH(η2-H2){η2-C,C-κ1-N-(CH2CH-o-C5H4N)}(PiPr3)2]BF4 with benzophenone affords [OsH2{κ2-C,O−C6H4C(O)Ph}{κ-C-(HNC5H3Et)}(PiPr3)2]BF4 as a result of the orthometalation of the ketone, the hydrogenation of the vinyl substituent of the pyridine, and its subsequent tautomerization. In acetonitrile, the ketone is released and complex [OsH{κ-C-(HNC5H3Et)}(NCCH3)(PiPr3)2]BF4 is formed., Financial support from the Spanish MEC (Projects CTQ2005-00656 and Consolider Ingenio 2010 CSD2007- 00006) and Diputación General de Aragón (E35) are acknowledged. K.G. thanks the Spanish MEC for her grant.

12 pages, 1 table, 15 figures, 1 scheme.-- Supporting Information Available: http://pubs.acs.org., Complex OsH3Cl(PiPr3)2 (1) reacts with KTp (Tp ) hydridotris(pyrazolyl)borate) in tetrahydrofuran at room temperature to give OsH3( 2-Tp)(PiPr3)2 (2). In toluene at 80 °C, the 2-Tp complex 2 is transformed to the 3-Tp derivative OsH3Tp(PiPr3) (3) in quantitative yield after 7 h. Protonation of 3 with HBF4 affords the bis(dihydrogen) compound [OsTp(è2-H2)2(PiPr3)]BF4 (4). In acetone complex 4 releases the coordinated hydrogen molecules in a sequential manner. At room temperature, the dihydrogensolvate complex [OsTp(è2-H2)( 1-OCMe2)(PiPr3)]BF4 (5) is formed, while at 56 °C the loss of both hydrogen molecules gives rise to the bis-solvento derivative [OsTp( 1-OCMe2)2(PiPr3)]BF4 (6). Complexes 2-6 have been characterized by X-ray diffraction analysis, and DFT calculations support their formulation. The structures of 3-5 have been compared with those of their Cp counterparts OsH3Cp(PiPr3), [OsH2- Cp(è2-H2)(PiPr3)]BF4, and [OsH2Cp( 1-OCMe2)(PiPr3)]BF4. The results show that the Tp ligand avoids piano stool geometries, while it enforces dispositions allowing N-Os-N angles close to 90° such as octahedron and pentagonal bipyramid., Financial support from the MEC of Spain (Projects CTQ2005-00656 and Consolider Ingenio 2010 CSD2007-00006) and Diputación General de Aragón (E35) is acknowledged.

10 pages, 5 figures, 4 schemes.-- Supporting Information Available: http://pubs.acs.org., Complex [OsH(CCCPh2)(CH3CN)2(PiPr3)2]BF4 (1) reacts with primary and secondary alcohols to give the corresponding dehydrogenated alcohols and the hydride-carbene derivative [OsH(CHCHCPh2)(CH3CN)2(PiPr3)2]BF4 (2), as a result of hydrogen transfer reactions from the alcohols to the Cα−Cβ double bond of the allenylidene ligand of 1. The reactions with phenol and t-butanol, which do not contain any β-hydrogen, afford the alkoxy-hydride-carbyne complexes [OsH(OR)(CCHCPh2)(CH3CN)(PiPr3)2]BF4 (R = Ph (3), tBu (4)), as a consequence of the 1,3-addition of the O−H bond of the alcohols to the metallic center and the Cβ atom of the allenylidene of 1. On the basis of the reactions of 1 with these tertiary alcohols, deuterium labeling experiments, and DFT calculations, the mechanism of the hydrogenation is proposed. In acetonitrile under reflux, the Os−C double bond of 2 undergoes hydrogenation to give 1,1-diphenylpropene and ¢Sq = -43.5 +/- 9.6 J mol-1 K-1. The X-ray structures of 2 and 3 are also reported., Financial support from the MEC of Spain (Project CTQ2005-00656) and Diputación General de Aragón (E35) is acknowledged. R.C. thanks CSIC and the European Social Fund for funding through the I3P Program.

13 páginas, 6 figuras, 7 tablas., The Ir(I)−butadiene complex TpMe2Ir(η4-CH2_C(Me)C(Me)_CH2) (1) (TpMe2 = hydrotris(3,5-dimethylpyrazolyl)borate) reacts with ≥3 equiv of DMAD (RC CR, R = CO2Me) in CH2Cl2 at 60 °C, in the presence of adventitious water, with formation of the iridacycloheptatriene (2), by the oxidative coupling of three molecules of DMAD in the metal coordination sphere. In a related process, TpMe2IrPh2(N2) (4) gives two benzoannelated iridacycloheptatrienes, the symmetrical species (5) and the unsymmetrical one (6). The water ligand in these complexes is labile, and derivatives substituted with CO, PMe3, and NCMe have been obtained. 2, 5, and 6 react, at 25 °C, with oxo-transfer oxidizing reagents such as tBuOOH with formation of the keto-metallabicyclic products 7−9, which result from the selective oxo attack to the γ,δ-C_C double bond, irrespective of this being of the benzo or the (R)C_C(R) type. In the latter case, further oxidation takes place with tBuOOH, at ambient temperature, with formation of an iridabenzene (11) and an iridanaphthalene (12) (with five and three electron-withdrawing CO2Me substituents, respectively) in which the carboxylate MeO2CCO2- ligand completes the metal coordination sphere. Interestingly, substitution of this group by OH- or MeO- allows the formation of Jackson−Meisenheimer complexes, reflecting the inherent aromaticity of these electron-deficient metalloaromatics. Finally, the hydrogenation of the iridacycloheptatrienes has been studied. All new compounds have been fully characterized by microanalysis, IR and NMR spectroscopies, and, in some cases, single-crystal X-ray diffraction studies., Financial support from the Spanish Ministerio de Educación y Ciencia (MEC) (projects CTQ2004-00409/BQU, FEDER support, and HU2003-039) and from the Junta de Andalucía is gratefully acknowledged. C.M.P., L.L.S., and N.R. thank the Junta de Andalucía and the MEC for research grants.