79572-36-4Relevant academic research and scientific papers
Synthesis and structure of endo-coordinated o-xylylene complexes of zerovalent ruthenium and osmium, M{η4-o-(CH2)2C6H 4}(PMe2Ph)3 (M = Ru, Os), and of a tricarbonyliron adduct of the ruthenium complex
Bennett, Martin A.,Bown, Mark,Goh, Lai Yoong,Hockless, David C. R.,Mitchell, Thomas R. B.
, p. 1000 - 1007 (2008/10/09)
Treatment of ruthenium(II) and osmium(II) salts [M(η6-o-C6H4Me2)(PMe 2Ph)3](PF6)2 [ M = Ru (3) or Os (4)] with KO-t-Bu gives o-xylylene (o-quinodimethane) complexes of zerovalent ruthenium and osmium, M{η4-endo-o-(CH2)2C6H 4}(PMe2Ph)3 [M = Ru (6) or Os (7)], in 83% and 41% yields, respectively. Crystals of 6 are monoclinic, space group C2/c, with a = 31.540(3) A?, b = 11.793(4) A?, c = 16.739(3) A?, β = 104.58(1)°, and Z = 8; those of 7 are monoclinic, space group C2/c, with a = 31.487(2) A?, b = 11.759(2) A?, c = 16.784(3) A?, β = 104.625(8)°, and Z = 8. The structures were solved by heavy-atom methods and refined by least-squares analysis to R = 0.035 and Rw = 0.027 for 3027 independent reflections (I > 3σ) (6) and R = 0.019 and Rw = 0.014 for 4258 independent reflections (I > 3σ) (7). Both molecules contain a metal atom coordinated in a distorted square-pyramidal arrangement by the double bonds of η4-endo-o-xylylene occupying two basal sites and three phosphorus atoms occupying the other sites. Variable temperature NMR (1H, 31P) spectra of 6 and 7 show the molecules to be fluxional as a consequence of hindered rotation of the M(PMe2Ph)3 fragment with respect to the o-xylylene, approximate ΔG? values being 56 kJ mol-1 at 314 K for 6 and 60 kJ mol-1 at 324 K for 7. Treatment of 6 with Fe(CO)4(NMe3) affords a heterobimetallic o-xylylene complex containing zerovalent ruthenium and zerovalent iron, i.e., endo-{Ru(PMe2Ph)3}-exo-{Fe(CO) 3}{μ-η4,η4-o-(CH2) 2C6H4} (8) in 42% yield, in which the ruthenium and iron atoms are coordinated to opposite sides of the o-xylylene ligand. Crystals of 8 are triclinic, space group P1, with a = 10.107(2) A?, b = 12.162(2) A?, c = 14.339(2) A?, α = 84.86(1)°, β = 80.69(1)°, γ = 86.00(1)°, and Z = 2. The structure was solved by direct methods and refined by least-squares methods to R = 0.034 and Rw = 0.024 for 5025 independent reflections (I > 3σ). In complex 8 both metal centers are coordinated in a distorted square-pyramidal arrangement. The coordination sphere of the ruthenium atom in 8 is identical to that of the ruthenium atom in 6; the basal sites of the square-pyramid about the iron atom are occupied by the exo pair of double bonds of o-xylylene, and the other three sites are occupied by the carbonyl ligands.
Double deprotonation of ruthenium(II) cations containing 1,2-dimethyl-substituted η6-arenes. Protonation of the resulting exo-coordinated (o-xylylene)ruthenium(0) complexes and X-ray crystal structures of the agostic (η3-pentamethylbenzyl)ruthenium(II) complexes [Ru{η3-(HCH2)(CH2)C6Me 4 ...
Bennett, Martin A.,Goh, Lai Yoong,McMahon, Ian J.,Mitchell, Thomas R. B.,Robertson, Glen B.,Turney, Terence W.,Wickramasinghe, Wasantha A.
, p. 3069 - 3085 (2008/10/08)
Full title: Double deprotonation of ruthenium(II) cations containing 1,2-dimethyl-substituted η6-arenes. Protonation of the resulting exo-coordinated (o-xylylene)ruthenium(0) complexes and X-ray crystal structures of the agostic (η3-pentamethylbenzyl)ruthenium(II) complexes [Ru{η3-(HCH2)(CH2)C6Me 4}{(Z)-Ph2PCH=CHPPh2}(PMe 2Ph)]PF6 and [Ru{η3-(HCH2)(CH2)C6Me 4}(PMe2Ph)3]PF6. Treatment of the various ruthenium(II) salts [Ru(ONO2)(η6-1,2-dimethylarene)L2]NO 3 and [Ru-(O2CCF3)(η6-1,2-dimethylarene)L 2]PF6 with KO-t-Bu or (Me3Si)2NNa in the presence of a ligand L′ gives o-xylylene (o-quinodimethane) complexes of zerovalent ruthenium, i.e. Ru{η4-(CH2)2C6Me 4}L2L′ (L = L′ = PMe2Ph, P(CD3)2Ph, PMePh2, P(OMe)3, P(OCH2)3CMe; L2 = Ph2PCH2CH2PPh2, L′ = PMe2Ph; L2 = (Z)-Ph2PCH=CHPPh2, L′ = PMe2Ph, P(CD3)2Ph), Ru{η4-(CH2)2H2Me 2}L2L′ (L = L′ = PMe2Ph, PMePh2), and Ru{η4-(CH2)2C6H 4}(PMe2Ph)3, in good to moderate yields. In all cases the o-xylylene group is coordinated through its exo pair of double bonds. The reactions are proposed to proceed via the undetected intermediates Ru(o-xylylene)L2 (L = monodentate P-donor ligand, L2 = bidentate P-donor ligand) in which the ruthenium atom can migrate from the endo to the exo pair of double bonds before ligand L′ attacks. On treatment with HPF6, Ru{η4-(CH2)2C6Me 4}L2L′ and Ru{η4-(CH2)2C6H 4}(PMe2Ph)3 give (η3-benzyl)ruthenium(II) salts [Ru{η3-(HCH2)(CH2)C6Me 4)L2L′]PF6 (L = Ph2PCH2CH2PPh2, L′ = PMe2Ph (1); L = (Z)-Ph2PCH=CHPPh2, L′ = PMe2Ph (2), P(CD3)2Ph (2a); L = L′ = PMe2Ph (3), P(CD3)2Ph (3a)) and [Ru{η3-(HCH2)-(CH2)C6H 4)(PMe2Ph)3]PF6 (4) in which the added proton bridges the metal atom and a terminal methylene group. Crystals of 2 are monoclinic, space group P21/n, with a = 18.884 (3) A?, b = 18.612 (3) A?, c = 12.361 (1) A?, β = 90.40 (1)°, and Z = 4; those of 3 are monoclinic, space group C2/c, with a = 21.220 (8) A?, b = 23.412 (10) A?, c = 18.580 (7) A?, β = 126.05 (1)°, and Z = 8. The structures were solved by heavy-atom methods and refined by least-squares analysis to R = 0.042 and Rw = 0.053 for 5787 independent reflections (I ≥ 3σ) (2) and R = 0.053 and Rw = 0.076 for 5832 independent reflections (I > 3σ) (3). Both cations contain a ruthenium atom coordinated in a distorted-octahedral arrangement by a η3-pentamethylbenzyl group, which occupies two sites, three phosphorus atoms, and an agostic methyl hydrogen atom that has been directly located in 2 but not 3. The η3-benzyl interaction in 2 shows the usual asymmetry, the shortest Ru-C bond being to the terminal CH2 group (Ru-C(22) = 2.164 (5) A?, Ru-C(2) = 2.342 (4) A?, Ru-C(1) = 2.358 (4) A?). The metrical parameters defining the agostic Ru-H-CH2 interaction in 2 are r(Ru-C) = 2.416 (5) A?, r(Ru-H) = 1.92 (4) A?, r(C-H) = 1.01 (5) A?, and ∠C-H-Ru = 107 (3)°. The distances from ruthenium to the terminal carbon atoms in 3 (Ru-C(11) = 2.333 (9) A?, Ru-C(22) = 2.283 (10) A?) are almost equal within experimental error, in contrast with the corresponding distances in 2, and indicate that the solid-state structure of 3 is an average in which either C(11) or C(22) is protonated. Variable-temperature NMR (1H, 31P) spectra of complexes 1, 2, 2a, 3, 3a, and 4 show these molecules to be fluxional as a consequence of three processes: (1) reversible Ru-H (agostic) bond breaking, which cannot be frozen out, even at -100°C; (2) reversible η3 ? η1 interconversions of the benzyl group, for which the estimated ΔG≠ values are ca. 13 kcal/mol at 303 K for 2 and ca 10 kcal/mol at 243 K for 3; (3) reversible C-H bond breaking in the Ru-H-CH2 bond, for which limiting high-temperature spectra cannot be reached owing to sample decomposition. For complexes 1-3, a combination of these processes enables the RuL3 fragment to circumnavigate the six-membered ring.
Preparation of η2: η2-o-Xylene Complexes of Ruthenium(o) via Facile ?-Hydrogen Abstraction Reactions. The Crystal and Molecular Structure of
Chappell, S. David,Cole-Hamilton, David J.,Galas, Anita M.R.,Hursthouse, Michael B.
, p. 1867 - 1872 (2007/10/02)
Reactions of cis- or trans-(L=PMe2Ph, PMePh2, or PEt3) with o-MeC6H4CH2MgBr produce as the only isolable product at temperatures down to -30 deg C, presumably by ?-hydrogen abstraction reactions.For L=PMe3 no reaction is observed but may be synthesised from and o-MeC6H4CH2Li'tmen (tmen = Me2NCH2CH2NMe2) in toluene.The yellow colour of the complexes, as well as their 1H and 31P n.m.r. spectra and their reaction with CO to give substitution products rather than adducts, suggest a diene like (η2:η2) binding of the xylene ligand.This is fully confirmed by an X-ray study of which is monoclinic, space group P21/c with a=15.919(2), b=11.643(2), c=16.674(3)A, β=104.60(30) grad, and Z=4.The structure was determined with 3 098 observed intensities measured on an automatic diffractometer and refined to an R value of 0.029.The co-ordination geometry can be considered as distorted square pyramidal with the diene molecule occupying two basal sites and bound through its exocyclicdouble bonds.The C-C distancessuggest localisation of bonding in the xylylene ring and the angle between the plane containing Ru,C(1),C(4) and extension of that of C(1),C(2),C(3),C(4) is 93 grad, confirming the η2:η2 binding of xylylene ligand.
Facile δ-Hydrogen Abstraction from a Ruthenium Complex; Possible 1-4η-Bonding of the o-Xylylene Ligand
Chappell, S. David,Cole-Hamilton, David J.
, p. 319 - 320 (2007/10/02)
Reaction of RuCl2L4 (L = PMe2Ph or PMePh2) with o-MeC6H4CH2MgBr in diethyl ether at room temperature leads to , whose spectroscopic and chemical characteristics suggest a possible 1-4η-bonding of the o-xylylene ligand.
