Angela Llamazares

Mercury—ruthenium mixed-metal carbonyl clusters containing 2-amido-6-methylpyridine (ampy) as a μ3,η2-ligand. Crystal structures of [Ru6(μ4-Hg)(μ3-ampy)2(CO)18]·2C4H8O and [Ru3(μ-HgBr)(μ3-ampy)(CO)9]

The cluster [Ru3(μ-H)(μ3-ampy)(CO)9] (1) (Hampy = 2-amino-6-methylpyridine) reacts with HgPh2 to give [Ru6(μ4-Hg)(μ3-ampy)2(CO)18] (2). An X-ray diffraction study of the solvate 2·2THF has shown it to contain two “Ru3(μ3-ampy)(CO)9” moieties bridged by a mercury atom which is bonded to the two NH-bridged ruthenium atoms of each trinuclear moiety. Complex 2 reacts with mercury(II) halides to give [Ru3(μ-HgX)(μ3-ampy)(CO9](X = Cl(3), Br(4), I(5)). The cystal structure of cluster 4 shows it to contain a HgBr fragment spanning the same RuRu edge as the amido group of the ampy ligand. Some reactions of the clusters 2 and 3 are also described.

Synthesis, structure and hydrogenation catalytic activity of [Ru3(μ3,η2-ampy)(μ,η1:η2-PhCCHPh)(CO)6(PPh3) (Hampy = 2-amino-6-methylpyridine)

Abstract The compound [RU 3 (μ 3 ,η 2 - -ampy)(μ 3 η 1 :η 2 -PhCCHPh)(CO) 6 (PPh 3 ) 2 ] ( 1 ) (ampy = 2-amino-6-methylpyridinate) has been prepared by reaction of [RU 3 (η-H)(μ 3 ,η 2 - ampy) (μ,η 1 :η 2 -PhCCHPh)(CO) 7 (PPh 3 )] with triphenylphosphine at room temperature. However, the reaction of [RU 3 (μ-H)(μ 3 , η 2 -ampy)(CO) 7 (PPh 3 ) 2 ] with diphenylacetylene requires a higher temperature (110°C) and does not give complex 1 but the phenyl derivative [RU 3 (μ 3 ,η 2 -ampy)(μ,η 1 :η 2 -PhCCHPh)(μ,-PPh 2 )(Ph)(CO) 5 (PPh 3 )] ( 2 ). The thermolysis of complex 1 (110°C) also gives complex 2 quantitatively. Both 1 and 2 have been characterized by0 X-ray diffraction methods. Complex 1 is a catalyst precursor for the homogeneous hydrogenation of diphenylacetylene to a mixture of cis - and trans -stilbene under mild conditions (80°C, 1 atm. of H 2 ), although progressive deactivation of the catalytic species is observed. The dihydride [RU 3 (μ-H) 2 (μ 3 ,η 2 -ampy)(μ,η 1 :η 2 - PhCCHPh)(CO) 5 (PPh 3 ) 2 ] ( 3 ), which has been characterized spectroscopically, is an intermediate in the catalytic hydrogenation reaction.

Synthesis, characterization, reactivity, and catalytic hydrogenation activity of the hexanuclear hexahydrido carbonyl cluster compound [Ru6(μ-H)60(μ3,ν2-ampy)2(CO)14 ] (Hampy = 2-amino-6-methylpyridine)

Abstract The reaction of the 48-electron complex [Ru 3 (μ-H)(μ 3 ,ν 2 -ampy)(CO) 9 ] (1) (Hampy = 2-amino-6-methylpyridine) with molecular hydrogen (1 atm, toluene, 110°C) gives the 92-electron hexanuclear hexahydrido derivative [Ru6(μ-H) 6 ( μ 3 , ν 2 -ampy) 2 (CO) 14 ] (2). This hexanuclear compound regenerates complex 1 when exposed to carbon monoxide. However, it undergoes CO substitution instead of ligand addition when treated with PR, to give [Ru6(μ-H) 6 (μ 3 ν 2 -ampy) 2 (PR 3 ) 2 (CO) 12 ] (R = 4-tolyl ( 3a ) or Ph ( 3b )). The X-ray diffraction structure of 3a indicates that it consists of two trinuclear fragments connected to each other through two bridging hydrides, and two weak metal-metal bonds. NMR experiments (1H, 13 C, homonuclear 1H NOE, and heteronuclear indirect 13 C- 1 H correlations) indicate that 2 is isostructural with 3a . Complex 2 is an efficient catalyst precursor for the homogeneous hydrogenation of unsaturated organic molecules. A kinetic analysis of the hydrogenation of diphenylacetylene under very mild conditions ( T = 323 K, P (H 2 ) 2 , first-order in hydrogen pressure and zero-order in substrate concentration, suggesting that the active catalytic species are hexanuclear.

Mercury-bridged transition-metal clusters. Synthesis of pentanuclear Ru3HgM (M Mo, W, or Co) clusters and X-ray structure of [(Ru3(μ3,η2-ampy)(CO)9)-(μ3-Hg)Co(CO)4] (Hampy 2-amino-6-methylpyridine)

Abstract Redistribution reactions of the compound [Ru 3 (μ-HgCl)(μ 3 ,η 3 -ampy)(CO) 9 ] ( 1 ) (Hampy = 2-amino-6-methylpyridine) with the metal-metal bonded transition-metal dimers [M 2 Cp 2 (CO) 6 ] (M  MO or W) and [CO 2 (CO) 8 ] give a separable mixture of the mixed-metal clusters [{RU 3 (μ 3 ,η 2 -ampy)(CO) 9 }(μ 3 -Hg)ML n ] (ML n  MOCp(CO) 3 ( 2 ), WCp(CO) 3 ( 3 ), Co(CO) 4 ( 4 )) and the corresponding chloro complexes [MClL n ]. The compounds 2–4 contain an Hg-ML n fragment spanning the same Ru-Ru edge as the amido moiety of the ampy ligand, as has been determined by 13 C NMR spectroscopy and, in the case of complex 4 , by an X-ray diffraction study. Crystal data for 4 : triclinic, space group P −1 , a = 9.598(3), b = 11.817(3), c = 12.835(6) A, α = 76.40(3), β = 75.34(4), γ = 83.34(3)°, V = 1366(1) A 3 , Z = 2; R = 0.0359, R W = 0.0362 for 3508 observed reflections and 372 variables.

Reactivity of a cationic triruthenium hydridoalkenylcarbonyl cluster complex toward nucleophilic reagents. Carbonyl substitution versus alkene elimination reactions

Abstract The reactions of the cationic hydridoalkenyl cluster complex [Ru 3 ( μ -H)( μ 3 -PhCCHPh)(CO) 8 ][BF 4 ] ( 1 ) (Hampy = 2-amino-6-methylpyridine) with neutral and anionic nucleophiles have been studied. Complex 1 reacts with different amounts of triphenylphosphine to replace CO giving [Ru 3 ( μ -H)( μ 3 -ampy)( μ -PhCCHPh)(PPh 3 )(CO) 7 ][BF 4 ] (two isomers), [Ru 3 ( μ -H)( μ 3 -ampy)( μ -PhCCHPh)(PPh 3 ) 2 (CO) 6 ][BF 4 ] and [Ru 3 ( μ -H)( μ 3 -ampy)( μ -PhCCHPh)(PPh 3 ) 3 (CO) 5 ][BF 4 ] (two isomers). Analogous results are obtained using tri-4-tolyphosphine. The reaction of compound 1 with two equivalents of bis(diphenylphosphino)methane (dppm) induces the reductive elimination of cis -stilbene, yielding [Ru 3 ( μ 3 -ampy)( μ -dppm)(dppm)(CO) 7 ]BF 4 ]. Complex 1 undergoes deprotonation upon treatment with NaOMe to give [Ru 3 ( μ 3 -ampy)( μ -PhCCHPh)(CO) 8 ]. However, a similar reaction with NaOH yields cis -stilbene and the neutral hydride [Ru 3 ( μ -H)( μ 3 -ampy)(CO) 9 ].

Reactivity of the Anionic Carbonyltrirhenium Cluster [Re3(µ‐H)3(µ3‐ampy)(CO)9]− − Synthesis of Neutral Phosphane and Alkenyl Derivatives

Protonation of the trinuclear anionic rhenium cluster [HNEt3][Re3(µ-H)3(µ3-ampy)(CO)9] (1) (Hampy = 2-amino-6-methylpyridine) with [HOEt2][BF4] at low temperature leads to dihydrogen and the neutral unsaturated dihydride derivative [Re3(µ-H)2(µ3-ampy)(CO)9]. The low thermal stability of this compound (it undergoes decomposition above 5 °C) has prevented its isolation as a pure solid. The compound [Re3(µ-H)3(CO)12] is the major product obtained when the protonation of 1 is carried out under CO. Protonation of 1 in the presence of phosphanes or alkynes gives the neutral derivatives [Re3(µ-H)2(µ3-ampy)(PR3)(CO)9] (2: R = Ph; 3: R = p-tolyl) or [Re3(µ3-H)(µ3-ampy)(µ-RC=CHR′)(CO)9] (4: R = R′ = Ph; 5: R = R′ =Et; 6a: R = Ph, R′ = H; 6b: R = H, R′ = Ph). In 2 and 3, the phosphane ligand is in an equatorial position on an Re atom of the NH-bridged Re−Re edge, cis to a hydride ligand and far away from the other hydride ion. In compounds 4−6, the alkenyl ligand, which arises from the insertion of the corresponding alkyne into an Re−H bond, is attached to two metal atoms in a µ-η1:η2 fashion, spanning the same Re−Re edge as the NH fragment of the ampy ligand. The hydride ligand of compounds 4−6 coordinates in a triply bridging fashion, capping the Re3 triangle. Compounds 4−6 represent the first examples of trirhenium clusters containing alkenyl ligands.

An exception to the general mechanism of CO insertion into the alkyl-manganese bond

Two-electron donor ligands L enter trans(and not cis as in other manganese examples) to the acyl group in the reaction of fac-[Mn(CO)3(bipy)(Me)]1 with L to give cis,trans-[Mn(CO)2(L)(bipy)(COMe)]2; the reaction of 1 with *CO (CO 99% enriched in 13C) gives cis,trans-[Mn(CO)2(*CO)(bipy)(COMe)]4, ruling out the formation of the possible intermediate cis,cis-[Mn(CO)2(L)(bipy)(COMe)]3.