Ysaura De Sanctis

Extrusion of selenium and tellurium atoms from selenophene and tellurophene by reaction with trinuclear iron, ruthenium, and osmium clusters: crystal structures of [Os6(μ-H)(μ3-Se)(μ4-C4H3)(CO)20] and of [Ru4(μ3-Se)μ-C4H4)(CO)11]

Abstract The trinuclear carbobyl clusters [Fe 3 (CO) 12 ], [Ru 3 (CO) 12 ], [Os 3 (CO) 11 (MeCN)], and [Os 3 (CO) 10 (MeCN) 2 ] react with selenophene and tellurophene ( cyclo -C 4 H 4 X, X = Se or Te) under mild conditions to give compounds containing the open-chain ligands CHCHCHCHX or the fragments X, C 4 H 4 , C 4 H 3 , or H as bridging ligands. The following compounds were isolated and characterised: [Os 3 (CO) 10 (C 4 H 4 X)], 1 where X = Se (X-ray structure reported previously) and 8 where X = Te, [Os 6 H(Se)(C 4 H 3 )(CO) 20 ], 2 , [Os 2 (CO) 6 (C 4 H 4 Se)], 3 , [Ru 2 (CO) 6 (C 4 H 4 )], 4 , [Ru 4 (CO) 6 (C 4 H 4 )], 4 , [Ru 4 (Se)(CO) 11 (C 4 H 4 )], 5 , [Fe 2 (CO) 6 (C 4 H 4 )], 6 , and [Fe 2 (CO) 6 (C 4 H 4 Se)], 7 . The clusters 2 and 5 were shown by single-crystal X-ray diffraction methods to have had both Seue5f8C bonds broken to give μ 3 -Se ligands in each case. Compound 2 contains an interesting μ 4 -C 4 H 3 ligand linking two Os 3 units through a μ-alkylidyne bridge, a σ-Osue5f8C bond, and an η 3 -allyl component. Compound 5 has a μ-C 4 H 4 ligand of a type previously found to be formed by alkyne coupling. The other compounds were characterised spectroscopically.

Carbon–hydrogen cleavage versus ring opening in the oxidative addition reactions of furan, thiophene, selenophene and tellurophene with [Os3(CO)10(MeCN)2]

Reactions of the cluster [Os3(CO)10(MeCN)2] with furan, thiophene, selenophene or tellurophene lead to compounds of corresponding stoichiometry, [Os3(CO)10(C4H4E)](E = O, S, Se or Te), but, whereas for E = O or S these are furyl or thienyl hydrido compounds formed by C–H cleavage, the Se and Te clusters are formed by E–C cleavage (X-ray structure for the E = Se cluster).

A comparison of the clusters [Os3(μ-H)(μ-X)(CO)10] where X is furyl, thienyl, pyrrolyl, or indolyl: monohapto versus dihapto and exo versus endo coordination

Abstract The thienyl complexes [Os 3 (μ-H)(μ-C 4 H 2 RS)(CO) 10 ] ( 1 , R = H and 2 , R = Me) were synthesised through the reactions of thiophene or 2-methylthiophene with [Os 3 (CO) 10 (MeCN) 2 ], which lead to Cue5f8H bond activation adjacent to the sulphur atom. The crystal structure when X = Me shows that the thienyl ligand is μ,η 2 -bonded, although the distance between an Os atom and the β-carbon is particularly long (Os(2)-C(2) 2.82(3) A), longer than the corresponding distance in the previously reported furyl complex 3 (2.63(1) A). The presence and interconversion of exo and endo isomers of these complexes in solution are described. The interconversion mechanism is believed to involve a transient heteroatom-bonded intermediate. N -Methylpyrrole similarly gives the stoichiometrically equivalent but structurally different cluster [Os 3 (μ-H)(μ-C 4 H 3 NMe)(CO) 10 ] ( 5 ) but in this case the crystal structure shows that the pyrrolyl ring is perpendicular to the OS 3 ring and is μ-η 1 -coordinated. Attempts to synthesise the directly analogous indol-2-yl complex, which we predict should be μ-η 2 -coordinated, like the furyl and thienyl compounds, led instead to the indol-3-yl isomer [Os 3 (μ-H)(μ-C 6 H 4 C 2 HNMe)(CO) 10 ] ( 6 ), again with vertical μ,η 1 -coordination, as shown by its crystal structure. A structural comparison of these compounds is presented.

Addition of diselenides RSe2R to [Os3(CO)10(MeCN)2] to give isomers of [Os3(μ-SeR)2(CO)10]

Abstract We have re-examined the oxidative addition reactions of the diselenides RSeSeR (R = Me or Ph) with [Os3(CO)10(MeCN)2] and find that the initial products are clusters which we believe should be formulated as [Os3(μ-RSe2R)(CO)10] [R = Ph (1a) and R = Me (1b) with retained Seue5f8Se bonds. Clusters 1 have only been partially characterized because they readily isomerize at room temperature or in contact with silica to the compounds [OS3(μ-SeR)2(CO)10] [R = Ph (2a) or R = Me (2b)]. Isomers 2 have the RSe groups bridging different osmiumue5f8osmium edges, one of which is metalue5f8metal bonded and the other is not; X-ray structures are reported for R = Me and Ph. The molecular structures of clusters 2a and 2b in the crystals differ only in the stereochemistry at one of the selenium atoms. Clusters 2 isomerize on heating to clusters 3 with both SeR bridges on the same osmiumue5f8osmium edge. Inversion at selenium is rapid in solution and invertomers of 2a and 2b were detected by NMR at low temperatures. Minor by-products of the thermal treatment of clusters 2 include [Os2(μ-SeR)2(CO)6] (4), [Os3(μ-Ph)(μ-PhCO)(μ3-Se)2(CO)8] (5) and [Os3(μ3-Se)2(CO)9] (6).

Reactions of acetylenic aldehydes, ethers and carboxylic acids with triosmium and triruthenium clusters

Abstract The hydrido cluster [Os3H2(CO)10] reacts with CHue5fcCCHO to give [OS3H (CO)10(CHue5fcCCHO)] in which the ligand is bridging as a three-electron donor through the oxygen and the unsaturated α-carbon atom. On thermolysis in refluxing cyclohexane, two compounds are formed. One is the isomer [Os3H(CO)10(cis-CHue5fbCHCHO)] which has an open structure with two Osue5f8Os bonds, since the organic ligand is now a five-electron donating bridge. The other product is the dinuclear derivative [OS2H(CO)6(cis-CHue5fbCHCHO)]. The clusters [Os3H2(CO)10], [Os3(CO)1O(MeCN)2] and [Ru3(CO)1O(MeCN)2] react with CHue5fcCCH2OMe to give [M3(CO)10(CHue5fbCCH2OMe)] (M = Ru or Os), [Os3(CO)9(RCCHCOCHue5fbCR)] and [Os3(CO)9{(RC2H)2CO}] (R = CH2OMe), where the last two correspond to alkyne-coupled products. [Os3H2(CO)10] and [Os3(CO)10(MeCN)2] react smoothly with CHue5fcCCO2H to give, as expected, the carboxylato derivative [Os3H (CO)10(CHue5fcCCO2)] which contains an uncoordinated alkyne group. With the aim of producing linked clusters we reacted this compound with [M3(CO)10(MeCN)2] (M = Ru or Os) to give the two linked clusters in high yields: [Os6H(CO)20(μ5-CHue5fcCCO2)] and [Os3Ru3H(CO)20(μ5-CHue5fcCCO2)].

Triple oxidative addition of the diselenide PhSeSePh to the cluster [Os3(CO)10(MeCN)2] to give the osmium(II) compound [Os3(µ-Ph)(µ-PhCO)(µ3-Se)2(CO)8]

The diselenide PhSeSePh reacts with [Os3(CO)10(MeCN)2] to give isomers of [Os3(CO)10(µ-SePh)2] which convert thermally to a compound of apparent formula [OS3(CO)9(SePh)2], which was shown by X-ray diffraction to be the triple oxidative addition product [Os3(µ-Ph)(µ-PhCO)(µ3-Se)2(CO)8] in which the diselenide has cleaved into four separate ligand fragments as all three osmium(0) atoms are oxidised to osmium(II) atoms by an overall six-electron oxidation.

Ring opening and extrusion of tellurium atoms in the reaction of benzo[b]tellurophene with trinuclear iron, ruthenium and osmium clusters: X-ray crystal structures of [Os2(μ-C8H6Te)(CO)10], [Os4(μ-C8H4)(μ3-Te)(CO11], [Ru(μ-C8H6Te)(CO)6)], [Ru4(μ3-Te)(μ-C8H6)(CO)11] and [Fe2)μ-C8H6Te(CO)6]

Abstract The trinuclear carbonyl clusters [Fe3(CO)12], [Ru3(CO)12], [Os3(CO)12] and [Os3(CO)10(MeCN)2] react with benzo[b]tellurophene under mild conditions, in refluxing tetrahydrofuran, to give compounds containing the open-chain ligands C6H4CHCHTe or the fragments Te and C8H6 as bridging ligands. The following compounds were isolated and characterised: [Os3(μ-C8H6Te)(CO)10] (1), [Os2(μ-C8H6Te)(CO)6] [Os2(μ-C8H6)(CO)6] (3) [Os4μ-C8H6)(μ3-Te(CO)11] (4), which were obtained were obtained from the reaction of [Os3(CO)12] and benzo[b]tellurophene. [Ru3(μ-C8H6)(CO)8)] (5) (X-ray reported previously) [Ru2(μ-C8H6Te)(CO)6] (6), [Ru2(μ-C8H6] (7) and [Ru4(μ3-Te(μ-C8H6)(CO)11] (8) were derived from the reaction of [Ru3(CO)12] and benzo[b]tellurophene; [Fe2(μ-C8H6Te)(CO)6] (9) and [Fe2(μ-C8H6)(CO)6] (10) were obtained from [Fe3(CO)12]. All the compounds were characterised by 1H NMR and IR spectroscopy in solution and 1, 4, 6, 8 and 9 were characterised by X-ray diffraction methods in the solid state. All the clusters were shown to have had a Teue5f8C bond broken to give the C6H4CHCHTe as a bridging ligand linking two metal atoms. Cluster 8 was shown by single-crystal X-ray diffraction methods to have had both Teue5f8C bonds broken to give a μ3-Te ligand and a C8H6 bridging ligand. This cluster contains a Te-capped triangle of ruthenium atoms and there is a spiked ruthenium atom supporting the bridging C8H6 ligand. In this case the Te atom has been extruded from the heterocycle but remains in the cluster. Crystal data: 1: monoclinic, space group P2 1 /a, a=12.326(7), b=13.821(4), c=13.538(5) A , β=107.01(3)°, Z=4; 4: monoclinic, space group P2 1 /n, a=16.740(2), b=8.684(3), c=18.536(4) A , β=112.87(1)°, Z=4; 6: monoclinic, space group P2 1 /a, a=12.291(3), b=12.098(5), c=22.880(4) A , β=95.24(2)°, Z=8 ; 8: monoclinic, space group P2 1 /n, a=14.376(4), b=11.268(4), c=15.313(4) A , β=96.27(2)°, Z=4 ; 9: monoclinic, space group P2 1 /a, a=12.094(3), b=11.737(3), c=22.632(4)r A , β=96.66(2)°,Z=8 . The structures were solved by direct methods and were refined by full-matrix least-squares to R=0.0309, 0.0364, 0.0348, 0.0220 and 0.0410 for 4073, 3628, 3414, 2005 and 4985 reflections with I>3σ(I), respectively.

Linkage of two trimetallic clusters through the bridging ligands C3HO2 and C3O2. Crystal structures of three clusters containing the components Os3CHCCO2Os3, Ru3CHCCO2Os3, and Os3CCCO2Os3

Abstract Reaction of propynoic acid (CHue5fcCCO2H) with [Os3(CO)10(MeCN)2] gives the species [Os3H(CHue5fcCCO2)(CO)10] containing a μ-carboxylato ligand and a non-coordinated acetylenic function which may be coordinated further. Reaction of this compound with [M3(CO)10(MeCN)2] (M = Os or RU) gives the linked cluster compounds [Os3(CO)10(CHue5fcCCO2)Os3H(CO)10] (1) and [Ru3(CO)10 (CHue5fcCCO2)Os3H(CO)10] (2), the crystal structures of which are reported. A comparison of the geometries of the compounds [M3(CO)10(alkyne)] (M = Os or Ru) is possible for the first time; each contains a μ-CO ligand, which is more symmetrical for M = Ru than for M = Os. The coordination geometries of the μ3-alkyne and the overall conformations of the linked clusters are very similar. Decarbonylation of 1 and 2 leads to [Os3H(CO)9(C3O2)Os3H(CO)10] (3) (crystal structure reported) and [Ru3H(CO)9(C3O2)Os3H(CO)10] (4) respectively.

Oxidative addition of 2,2′-dipyridyl disulfphide to the cluster [Os3(CO)10(MeCN)2]

Abstract The cluster [Os 3 (CO) 10 (MeCN) 2 ] reacts with 2,2′-dipyridyl disulphide ( 1 , pySSpy) to give a range of oxidative addition products which were separated by TLC on silica and crystallization : [Os 3 (pyS) 2 (CO) 10 ] ( 2 ), [Os 3 (pyS) 2 (CO) 9 ] ( 3 ), [Os 2 (pyS) 2 (CO) 6 ] ( 4 ) and [Os(pyS) 2 (CO) 2 ] ( 5 ), together with some of the hydride [Os 3 H(pyS)(CO) 9 ] ( 6 ), which is not an expected oxidative addition product. The X-ray crystal structures of compounds 2, 3, 4 and 6 (compounds 2 and 6 occurring within a single crystal), together with the known structure of compound 5 , reveal several modes of pyS bonding : chelating pyS, μ 2 -pyS (both sulphur-bonded and nitrogen, sulphur-bonded) and μ 3 -pyS.

Ring opening versus phenyl–phosphorus bond cleavage in incorporating a phosphole into triosmium clusters

The five-membered heterocyclic compound 3,4-dimethyl-1-phenylphosphole (Ph[graphic omitted]H) reacts with [Os3(CO)11(MeCN)] or [Os3(CO)10(MeCN)2] to give the simple substitution products [Os3(CO)12–x(PhPC4H2Me2)x](x= 1 or 2) in which the phospholes are co-ordinated as tertiary phosphines through the phosphorus atoms. Thermolysis of these compounds gives decarbonylation compounds containing modified phosphole ligands. Phosphorus–carbon bonds either to the phenyl group or within the five-membered ring have been cleaved. The X-ray structure of the main product [Os3(CO)9(µ3-PhPCHCMeCMeCH)]1 shows that the organic µ3 ligand is a six-electron donor which is co-ordinated differently from the corresponding eight-electron donating ligand derived from 1-phenylphosphole in the cluster [Os3(CO)9(µ3-PhPCHCHCHCH)]. There is evidence for the reversible generation of this alternative from, 3, of the methylated compound 1 by photolysis. A minor product of the thermolysis is the hydrido cluster [Os3(µ-H)(µ-[graphic omitted]H)(µ3-C6H4)(CO)9]2 which contains a five-membered phospholyl ring and an o-phenylene (benzyne) ligand which originated from the phenyl group. The X-ray structure shows that the phospholyl ligand bridges two osmium atoms as a phosphido ligand through the phosphorus atom. The major and minor products, 1 and 2, are both derived by C–P bond cleavage, either in the phosphole ring or to the phenyl substituent respectively.