34692-07-4Relevant academic research and scientific papers
Effect (or lack thereof) of ancillary groups on the preparation and spectroscopic properties of ruthenium silyl complexes containing the Cp(PR3)2Ru moiety
Freeman, Samuel T.N.,Lofton, Lori L.,Lemke, Frederick R.
, p. 4776 - 4784 (2008/10/08)
The preparation and characterization of Cp(PR3)2RuSiX3 [PR3 = PPhMe2, SiX3 = SiCl3 (1), SiHCl2 (2), SiH2Cl (3), SiHMeCl (4), SiH3 (7), SiMeH2 (8), SiMe3 (9); PR3 = PPh2Me, SiX3 = SiCl3 (10), SiHCl2 (5), SiH2Cl (6), SiMeCl2 (11)] are described. Ruthenium silyl complexes 1-6 are prepared by the reaction of the ruthenium hydrides, Cp(PR3)2RuH, with the corresponding chlorosilane, ClSiX3; the ruthenium dihydrides [Cp(PR3)2RuH2]Cl were obtained as coproducts. Increasing the steric demand of the phosphine decreased the reactivity of the corresponding ruthenium hydride toward chlorosilanes. Silyl complexes 1-4 undergo chloride/hydride exchange with LiAlH4 to give the corresponding ruthenium hydrosilyl complexes Cp(PPhMe2)2RuSiHX2 [SiHX2 = SiH3 (7), SiMeH2 (8)]. Methylation of 1 with AlMe3 produces Cp(PPhMe2)2RuSiMe3 (9). Complexes 10 and 11 were prepared by the reaction of Cp(PPh2Me)2RuMe with neat hydrosilanes HSiX3 (SiX3 = SiCl3, SiMeCl2) at 100 °C. The effects of the silicon substituents on the spectroscopic properties of 1-11 and the related Cp(PMe3)2RuSiX3 complexes were examined as a function of Tolman's electronic parameter (χi) for the substituents on silicon. The NMR resonance PR3 δ(31P) and the NMR coupling constants, 1JSiH and 2JSiP, exhibit a linear relationship with ∑χi(SiX3). On the other hand, the silyl groups differentiated into three classes, dichlorosilyl, monochlorosilyl, and non-chlorosilyl , when the NMR resonances SiX3 δ(29Si), SiH δ(1H), and SiMe δ(13C) were examined as a function of ∑χi(SiX3). This chloro effect was attributed to Ru-Si silylene character from d(Ru)-*(Si-Cl) π-back-bonding interactions. Surprisingly, changing the phosphine attached to ruthenium had no effect on the spectroscopic properties of the silyl group.
Effect of ancillary ligation on the relative bond disruption enthalpies of Ru-H and Ru-Cl bonds in Cp(PR3)2RuX (PR3 = PMe3, PMe2Ph, PMePh2, PPh3; X = H, Cl)
Freeman, Samuel T.N.,Lemke, Frederick R.,Haar, Christopher M.,Nolan, Steven P.,Petersen, Jeffrey L.
, p. 4828 - 4833 (2008/10/08)
The ruthenium chloride and hydride complexes Cp(PR3)2RuH {X = Cl; PR3 = PMe3 (1), PMe2Ph (2), PMePh2 (3), PPh3 (4); X = H; PR3 = PMe3 (5), PMe2Ph (6), PMePh2 (7), PPh3 (8)} were studied by spectroscopy and solution calorimetry. The structures of 2 and 3 are reported and complete the structural characterization of the series 1-4. In this series, the Ru-Cl distance (2.449 ± 0.007 A?) remains constant, while the Ru-PR3 distance increases in the order 1 2 3 4. The ruthenium hydrides 5-8 were prepared from the reaction of the corresponding ruthenium chloride with KOMe in methanol.
Cyanide Ligand Basicities in Cp′M(L)2CN Complexes (M = Ru, Fe). Correlation between Heats of Protonation and vCN
Nataro, Chip,Chen, Jiabi,Angelici, Robert J.
, p. 1868 - 1875 (2008/10/08)
Basicities of the cyanide ligands in a series of Cp′M(L)2CN complexes were investigated by measuring their heats of protonation (-δHCNH) by CF3SO3H in 1.2-dichloroethane solution at 25.0 °C to give Cp′M(L)2(CNH)+CF3SO3 -, in which the N-H+ group is probably hydrogen-bonded to the CF3SO3- anion. Basicities (-δHCNH) of the CpRu(PR3)2CN complexes increase from 20.5 (PPh3) to 22.4 (PMe3) kcal/mol with increasing donor abilities of the phosphine ligands. Basicities of all the Cp′Ru(PR3)2CN complexes, where Cp′ = Cp or Cp*, are linearly correlated with their vCN values; the nonphosphine complexes. CpRu(l.10-phen)CN and CpRu(COD)CN, do not follow the same correlation. For a large number of Cp′M(L)2CN complexes (M = Ru, Fe, L2 = mono- and bidentate phosphines, CO, 1,10-phen, and COD), their vCN values parallel vCN values of their protonated Cp′M(L)2(CNH)+ analogues. Also, 31P NMR chemical shifts of the unprotonated Cp′M(PR3)2-CN and protonated CpM(PR3)2(CNH)+ complexes are linearly related. Despite the high basicity of Ru in Cp*Ru-(PMe3)2Cl (30.2 kcal/mol), the CN- in Cp*Ru(PMe3)2CN (25.0 kcal/mol) is the site of protonation: factors that determine whether protonation occurs at the Ru or the CN- are discussed.
