| 1. |
- Begum, Noorjahan, et al.
(författare)
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Chelate and bridge diphosphine isomerization: triosmium and triruthenium clusters containing 1,1-bis(diphenylphosphino)ferrocene (dppf)
- 2007
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Ingår i: Organometallics. - : American Chemical Society (ACS). - 1520-6041 .- 0276-7333. ; 26:25, s. 6462-6472
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Tidskriftsartikel (refereegranskat)abstract
- The coordination mode of dppf {dppf = 1,1'-bis(diphenylphosphino)ferrocene} at triosmium and triruthenium carbonyl clusters has been studied. Heating [Os3(CO)12] with dppf in the presence of Me3NO in benzene at 60 C furnishes three triosmium compounds, [Os3(CO)11(1-dppf)] (1), [Os3(CO)10(2-dppf)] (2), and [Os3(CO)10(-dppf)] (3) in 10, 20, and 30% yields, respectively. Reaction of the labile cluster [Os3(CO)10(MeCN)2] with dppf at room temperature also gives 1, 2, and 3 (5, 10, and 35% yields). Treatment of 1, which contains a pendant diphosphine, with Me3NO at room temperature affords 2 via a ring closure reaction, whereas heating 2, in which the dppf ligand is chelating, at 110 C affords the thermodynamically stable bridging isomer 3, in which phosphorus atoms are bound at equatorial positions. Reaction of the unsaturated cluster [Os3(CO)10(-H)2] (4) with dppf in refluxing THF affords the bridging complex [Os3(CO)8(-dppf)(-H)2] (6) in high yield as the sole product. Hydrogenation of 3 with H2 at 110 C at 1 atm also yields 6. Reactions of both the saturated [Os3(CO)10(-dppm)] (7) and electron-deficient [Os3(CO)8{3-Ph2PCH2P(Ph)C6H4}(-H)] (8) with dppf at 110 C and at room temperature respectively yield [Os3(CO)9(-dppm)(1-dppf)] (9) and [Os3(CO)8(-dppm)(2-dppf)] (10). Compound 9 converts to 10 at 110 C via CO loss and phosphorus coordination. Reaction of [Ru3(CO)12] with dppf in the presence of Me3NO affords the dihydroxy-bridged complex, [Ru3(CO)8(-dppf)(-OH)2] (13), together with the previously reported compounds [Ru3(CO)10(-dppf)] (11) and [Ru3(CO)8(-dppf)2] (12).
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| 2. |
- Begum, Noorjahan, et al.
(författare)
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Reaction of [Ru-3(CO)(12)] with tri(2-furyl)phosphine: Di- and tri-substituted triruthenium and phosphido-bridged diruthenium complexes
- 2008
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Ingår i: Journal of Organometallic Chemistry. - : Elsevier BV. - 0022-328X. ; 693:8-9, s. 1645-1655
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Tidskriftsartikel (refereegranskat)abstract
- Reaction of [Ru-3(CO)(12)] with tri(2-furyl)phosphine, P(C4H3O)(3), at 40 degrees C in the presence of a catalytic amount of Na[Ph2CO] furnishes two triruthenium complexes [Ru-3(CO)(10){P(C4H3O)(3)}(2)] (1) and [Ru-3(CO)(9){P(C4H3O)(3)}(3)] (2) with the ligand coordinated through the phosphorus atom. Treatment of 1 and 2 with Me3NO at 40 degrees C affords the dinuclear phosphido-bridged complexes [Ru-2(CO)(6)(mu-eta(1),eta(2)-C4H3O){mu-P(C4H3O)(2)}] (3) and [Ru-2(CO)(5)(mu-eta(1),eta(2)-C4H3O){mu-P(C4H3O)(2)}{P(C4H3O)(3)}] (4), respectively, that are formed via phosphorus-carbon bond cleavage of a coordinated phosphine followed by coordination of the dissociated furyl moiety to the diruthenium center in a sigma,pi-alkenyl mode. Reaction of [Ru-3(CO)(12)] with tri(2-furyl) phosphine in refluxing benzene gives, in addition to 3 and 4, low yields of the cyclometallated complex [Ru-3(CO)(9){mu-eta(1),eta(1)-P(C4H3O)(2)(C4H2O)}(2)] (5). Treatment of 3 with EPh3 (E = P, As, Sb) at room temperature yields the monosubstituted derivatives [Ru-2(CO)(5)(mu-eta(1),eta(2)-C4H3O){mu-P(C4H3O)(2)}(EPh3)] (E = P, 8; E = As, 9; E = Sb, 10). Similar reactions of 3 with P(C4H3O)(3), P(OMe)(3) and (BuNC)-N-t yield 4, [Ru-2(CO)(5)(mu-eta(1),eta(2)-C4H3O){mu-P(C4H3O)(2)}{P(OMe)(3)}] (11) and [Ru-2(CO)(5)(mu-eta(1),eta(2)-C4H3O){mu-P(C4H3O)(2)}(NCBut)] (12), respectively. The molecular structures of complexes 3, 4 and 8 have been elucidated by single crystal X-ray diffraction studies. Each complex contains a bridging sigma,pi-alkenyl group and while in 4 the phosphine is bound to the sigma-coordinated metal atom, in 8 it is at the pi-bound atom. Protonation of 3 and 4 gives the hydride complexes [(mu-H)Ru-2(CO)(6)(mu-eta(1),eta(2)-C4H3O){mu-P(C4H3O)(2)}](+) (6) and [(mu-H)Ru-2(CO)(5)(mu-eta(1),eta(2)-C4H3O){mu-P(C4H3O)(2)}{P(C4H3O)(3)}] (+) (7), respectively, while heating 3 with dimethylacetylenedicarboxylate (DMAD) in refluxing toluene gives the cyclotrimerization product, C-6(CO2Me)(6).
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| 3. |
- Ghosh, Shishir, et al.
(författare)
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Activation of tri(2-furyl)phosphine at a dirhenium centre: Formation of phosphido-bridged dirhenium complexes
- 2009
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Ingår i: Journal of Organometallic Chemistry. - : Elsevier BV. - 0022-328X. ; 694:18, s. 2941-2948
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Tidskriftsartikel (refereegranskat)abstract
- Reaction of tri(2-furyl) phosphine (PFu(3)) with [Re-2(CO)(10) (n)(NCMe)(n)] (n = 1, 2) at 40 degrees C gave the substituted complexes [Re-2(CO)(10) (n)(PFu(3))(n)] (1 and 2), the phosphines occupying axial position in all cases. Heating [Re-2(CO)(10)] and PFu(3) in refluxing xylene also gives 1 and 2 together with four phosphido-bridged complexes; [Re-2(CO)(8) (n)(PFu(3))(n)(mu-PFu(2))(mu-H)] (n = 0, 1, 2) (3-5) and [Re-2(CO)(6)(PFu(3))(2)(mu-PFu(2))(mu-Cl)] (6) resulting from phosphorus-carbon bond cleavage. A series of separate thermolysis experiments has allowed a detailed reaction pathway to be unambiguously established. A similar reaction between [Re-2(CO)(10)] and PFu(3) in refluxing chlorobenzene furnishes four complexes which include 1, 2, 6 and the new binuclear complex [Re-2(CO)(6)(eta(1)-C4H3O)(2)(mu-PFu(2))(2)] (7). All new complexes have been characterized by a combination of spectroscopic data and single crystal X-ray diffraction studies. (C) 2009 Published by Elsevier B.V.
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| 4. |
- Ghosh, Shishir, et al.
(författare)
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Carbon-hydrogen bond activation of phenyldi(2-thienyl)phosphine at a triosmium cluster centre
- 2010
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Ingår i: Inorganica Chimica Acta. - : Elsevier BV. - 0020-1693. ; 363:7, s. 1611-1614
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Tidskriftsartikel (refereegranskat)abstract
- The phenyldi(2-thienyl)phosphine (PhPTh2) complexes [Os-3(CO)(12-n)(PhPTh2)(n)] (n = 1-3) (1-3) have been prepared. Thermolysis of 1 and either 2 or 3 in octane affords carbon-hydrogen bond activation products [Os-3(CO)(9){mu(3)-PPhTh(C4H2S)}(mu-H)] (4) and [Os-3(CO)(8)(PPhTh2){mu(3)-PPhTh(C4H2S)}(mu-H)] (5), respectively. Both exist as isomeric mixtures differing in the relative positions of phenyl and thienyl substituents with respect to the triosmium centre. The nature of the process has been confirmed by a single crystal X-ray diffraction analysis of 4. (C) 2010 Elsevier B.V. All rights reserved.
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| 5. |
- Ghosh, Shishir, et al.
(författare)
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Electrocatalytic proton reduction by thiolate-capped triiron clusters [Fe3(CO)9(μ3-SR)(μ-H)] (R = iPr, tBu)
- 2018
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Ingår i: Inorganica Chimica Acta. - : Elsevier BV. - 0020-1693. ; 480, s. 47-53
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Tidskriftsartikel (refereegranskat)abstract
- The redox behaviour and electrocatalytic proton reduction ability of the thiolate-capped triiron clusters [Fe3(CO)9(μ3-SR)(μ-H)] (1, R = iPr; 2, R = tBu) have been investigated. In CH2Cl2, both show a quasi-reversible reduction and an irreversible oxidation. The thiol substituent has a significant influence on their reduction potentials (E1/2 = −1.24 V for 1 and E1/2 = −1.40 V for 2 vs. Fc+/Fc) but less impact on oxidation potentials (E1/2 = 0.99 V for 1 and E1/2 = 0.93 V for 2 vs. Fc+/Fc). Reduction is quasi-reversible and DFT studies reveal that this is due to scission of an iron-iron bond. While the clusters are not protonated by CF3CO2H or HBF4·Et2O, they can catalyse proton reduction of these acids at their corresponding reduction potentials following an ECEC mechanism.
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| 6. |
- Ghosh, Shishir, et al.
(författare)
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Hydrogenase biomimetics with redox-active ligands : Electrocatalytic proton reduction by [Fe2(CO)4(κ2-diamine)(μ-edt)] (diamine = 2,2′-bipy, 1,10-phen)
- 2016
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Ingår i: Polyhedron. - : Elsevier BV. - 0277-5387. ; 116, s. 127-135
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Tidskriftsartikel (refereegranskat)abstract
- Diiron complexes bearing redox active diamine ligands have been studied as models of the active site of [FeFe]-hydrogenases. Heating [Fe2(CO)6(μ-edt)] (edt = 1,2-ethanedithiolate) with 2,2′-bipyridine (2,2′-bipy) or 1,10-phenanthroline (1,10-phen) in MeCN in the presence of Me3NO leads to the formation of [Fe2(CO)4(κ2-2,2′-bipy)(μ-edt)] (1-edt) and [Fe2(CO)4(κ2-1,10-phen)(μ-edt)] (2-edt), respectively, in moderate yields. In the solid state the diamine resides in dibasal sites, while both dibasal and apical–basal isomers are present in solution. Both stereoisomers protonate readily upon addition of strong acids. Cyclic voltammetry in MeCN shows that both complexes undergo irreversible oxidation and reduction, proposed to be a one- and two-electron process, respectively. The structures of neutral 2-edt and its corresponding one- and two-electron reduced species have been investigated by DFT calculations. In 2-edt−the added electron occupies a predominantly ligand-based orbital, and the iron–iron bond is maintained, being only slightly elongated. Addition of the second electron affords an open-shell triplet dianion where the second electron populates an Fe–Fe σ*antibonding orbital, resulting in effective scission of the iron–iron bond. The triplet state lies 4.2 kcal mol−1lower in energy than the closed-shell singlet dianion whose HOMO correlates nicely with the LUMO of the neutral species 2-edt. Electrocatalytic proton reduction by both complexes has been studied in MeCN using CF3CO2H as the proton source. These catalysis studies reveal that while at high acid concentrations the active catalytic species is [Fe2(CO)4(μ-H)(κ2-diamine)(μ-edt)]+, at low acid concentrations the two complexes follow different catalytic mechanisms being associated with differences in their relative rates of protonation.
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| 7. |
- Ghosh, Shishir, et al.
(författare)
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Reactivity of phenyldi(2-thienyl) phosphine towards group 7 metal carbonyls: Carbon-phosphorus bond activation
- 2009
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Ingår i: Inorganica Chimica Acta. - : Elsevier BV. - 0020-1693. ; 362:15, s. 5175-5182
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Tidskriftsartikel (refereegranskat)abstract
- Addition of phenyldi(2-thienyl) phosphine (PPhTh2) to [Re-2(CO)(10-n)(NCMe)(n)] (n = 1, 2) affords the substitution products [Re-2(CO)(10-n)(PhPTh2)(n)] (1, 2) together with small amounts of fac-[ClRe(CO)(3)(PPhTh2)(2)] (3) (n = 2). Reaction of [Re-2(CO)(10)] with PPhTh2 in refluxing xylene affords a mixture which includes 2, [Re-2(CO)(7)(PPhTh2)(mu-PPhTh)(mu-H)] (4), [Re-2(CO)(7)(PPhTh2)(mu-PPhTh)(mu-eta(1), kappa(1)(S)-C4H3S)] (5) and mer[HRe(CO)(3)(PPhTh2)(2)] (6). Phosphido-bridged 4 and 5 are formed by the carbon-phosphorus bond cleavage of the coordinated PPhTh2 ligand, the cleaved thienyl group being retained in the latter. Reaction of [Mn-2(CO)(10)] with PPhTh2 in refluxing toluene affords [Mn-2(CO)(9)(PPhTh2)] (7) and the carbon-phosphorus bond cleavage products [Mn-2(CO)(6)(mu-PPhTh)(mu-eta(1),eta(5)-C4H3S)] (8) and [Mn-2(CO)(5)(PPhTh2)(mu-PPhTh)(mu-eta(1),eta(5)-C4H3S)] (9). Both 8 and 9 contain a bridging thienyl ligand which is bonded to one manganese atom in a eta(5)-fashion. (C) 2009 Elsevier B. V. All rights reserved.
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| 8. |
- Ghosh, Shishir, et al.
(författare)
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Reactivity of the triruthenium ortho-metalated cluster [Ru-3(CO)(9){mu(3)- eta(1), kappa(1),kappa(2)-PhP( C6H4) CH2PPh}] with tri(2-thienyl) phosphine and tri( 2-furyl) phosphine: Formation of 1,3-diphenyl-2,3-dihydro-1H-1,3-benzodiphosphine complexes via phosphorus-carbon bond formation
- 2009
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Ingår i: Journal of Organometallic Chemistry. - : Elsevier BV. - 0022-328X. ; 694:20, s. 3312-3319
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Tidskriftsartikel (refereegranskat)abstract
- Reaction of [Ru(CO)(9){mu(3-)eta(1),kappa(1),kappa(2)-PhP(C6H4)CH2PPh}] (1) with tri(2-thienyl) phosphine (PTh3) in refluxing THF afforded [Ru-3(CO)(9)(PTh3)(mu-dpbm)] (3){dpbm = PhP(C6H4)(CH2)PPh} and [Ru-3(CO)(6)(mu-CO)(2){mu-kappa(1),eta(1)-PTh2(C4H2S)}{mu(3)-kappa(1),ka ppa(2)-Ph2PCH2PPh}] (5) in 18% and 12% yields, respectively, while a similar reaction with tri(2-furyl)phosphine (PFu(3)) gave [Ru-3(CO)(9)(PFu(3))(mu-dpbm)] (4) and [Ru-3(CO)(7)(mu-eta(1),eta(2)-C4H3O)(mu-PFu(2)){mu(3)-eta(1),kappa(1),ka ppa(2)-PhP(C6H4)CH2PPh}] (6) in 24% and 27% yields, respectively. Compounds 2 and 4 are phosphine adducts of 1 in which the diphosphine ligand is transformed into 1,3-diphenyl-2,3-dihydro-1H-1,3-benzodiphosphine(dpbm) via phosphorus-carbon bond formation. Cluster 5 results from metalation of a thienyl ring, the cleved proton being transfoerred to the diphosphine.Carbon-phosphorus bond clevarge of a PFu(3) ligand is observed in 6 to afford a phosphido-bridge and furyl fragment, the latter bridging in a sigma,pi-vinyl fashion. The molecular strucutres of 3,5 and 6 have been determined by X-ray diffraction studies. (C) 2009 Published by Elsevier B.V.
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| 9. |
- Ghosh, Shishir, et al.
(författare)
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Unsymmetrical alkyne binding to a triruthenium centre: Oxidative-addition of diphenyl ditelluride to the furyne cluster [Ru-3(CO)(7)(mu-H)(mu(3)-eta(2)-C4H2O){mu-P(C4H3O)(2)}(mu-dppm)]
- 2011
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Ingår i: Journal of Organometallic Chemistry. - : Elsevier BV. - 0022-328X. ; 696:10, s. 1982-1989
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Tidskriftsartikel (refereegranskat)abstract
- Oxidative-addition of PhTe2Ph to the furyne cluster [Ru-3(CO)(7)(mu-H)(mu(3)-eta(2)-C4H2O){mu-P(C4H3O)(2)}(mu-dppm)] (1) results in the isolation of four complexes; (i) the previously reported 54-electron cluster [Ru-3(CO)(6)(mu(3)-Te)(2)(mu-TePh)(2)(mu-dppm)] (5) which results from elimination of trifuryl phosphine, (ii) the furenyl cluster [Ru-3(CO)(5)(mu-eta(2)-C4H3O){mu-P(C4H3O)(2)}(mu-TePh)(2)(mu-dppm)] (6) which results from carbon-hydrogen bond formation and (iii) two new 50-electron complexes [Ru-3(CO)(5)(mu-H)(mu(3)-eta(2)-C4H2O){mu-P(C4H3O)(2)}(mu-TePh)(2)(kappa (2)-dppm)] (7) and [Ru-3(CO)(4)(mu-H){P(C4H3O)(3)}(mu(3)-eta(2)-C4H2O){mu-P(C4H3O)(2)}(mu-T ePh)(2)(kappa(2)-dppm)] (8) both containing unsymmetrical furyne ligands. The structures of all the new compounds have been unambiguously established by single crystal X-ray crystallography. Further reactivity studies have provided a clear understanding of the relative sequence of the key oxidative-addition and reductive-elimination processes, showing that 6 is an intermediate in the formation of 7. DFT calculations have been used to shed light on the unsymmetrical binding of the furyne ligand in 7 and also to show that the adopted position of the heteroatom within the furyne ring can vary within complexes of this type. (C) 2010 Elsevier B.V. All rights reserved.
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| 10. |
- Hogarth, Graeme, et al.
(författare)
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Cluster chemistry in the Noughties: new developments and their relationship to nanoparticles
- 2010
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Ingår i: Dalton Transactions. - : Royal Society of Chemistry (RSC). - 1477-9234 .- 1477-9226. ; 39:27, s. 6153-6174
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Tidskriftsartikel (refereegranskat)abstract
- Over the past decade, the chemistry of low-valent transition metal clusters has again come to the fore, primarily as a result of the development of nanochemistry and the realization that large clusters are on the cusp of the nano-domain. This perspective focuses on these recent developments in low-valent transition metal cluster chemistry, specifically looking at cluster-nanoparticles, the use of small and medium sized clusters as nanoparticle precursors, the development of clusters as homogeneous catalysts and hydrogen uptake and storage systems, together with fundamental discoveries relating to novel transformations that can take place within the cluster framework.
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