162340-65-0Relevant academic research and scientific papers
14-Electron four-coordinate Ru(II) carbyl complexes and their five-coordinate precursors: Synthesis, double agostic interactions, and reactivity
Huang, Dejian,Streib, William E.,Bollinger, John C.,Caulton, Kenneth G.,Winter, Rainer F.,Scheiring, Thomas
, p. 8087 - 8097 (2007/10/03)
The structure of five-coordinate Ru(II) complexes RuHCl(CO)(PiPr3)2,1, RuCl2(CO)(PiPr3)2, 2, and Ru(Ph)Cl(CO)(PtBu2Me)2, 12, are reported. All three of these complexes have square-based pyramid geometry with the strongest σ-donor ligand trans to the vacant site. These 16-electron complexes do not show bona fide agostic interactions. This is attributed to the strong trans influence ligand (H, CO, and Ph) and π-donation of the Cl, which is further supported by the fact that two agostic interactions are present in the Cl- removal product of 12, i.e., the four-coordinate [RuPh(CO)L2]BAr′4 (L = PtBu2Me, Ar′ = 3,5-C6H3(CF3)2), 16. Structural comparison of 16 and 12 reveals that removal of Cl- does not change the remaining ligand arrangements but creates two low-lying LUMOs for agostic interactions, which persist in solution as evidenced by IR spectroscopy. Reactions of 16 with E-H (E = B, C(sp)) bonds cleave the Ru-Ph bond and form Ru-E/H bonds by different mechanisms. The reaction with catecholborane gives [RuH(CO)L2]BAr′4, which further reacts with catecholborane to give [Ru(BR2)(CO)L2]BAr′4. However, the reaction with Me3SiCCH undergoes a multistep transformation to give a PhCCSiMe3- and Me3SiCCH-coupled product, the mechanism of which is discussed. Reaction of RuCl2(CO)L2 with 1 equiv MeLi affords RuMeCl(CO)L2, 5, which further reacts with MeLi forming RuMe2(CO)L2, 7. Variable-temperature 13C{1H} NMR spectra reveal the two methyls in 7 are inequivalent and exchange by overcoming an energy barrier of 6.8 kcal/mol at -30 °C. The chloride of 5 can be removed to give [RuMe(CO)L2]BAr′4.
[Ru(Ph)(CO)(PtBu2Me)2]+: A unique 14-electron Ru(II) complex with two agostic interactions
Huang,Streib,Eisenstein,Caulton
, p. 2004 - 2006 (2007/10/03)
A nonplanar arrangement of four ligands is intrinsic to the title compound in solution and in the crystal. There is no interaction between the Ru center and the counterion [3,5-(CF3)2C6H3]4B-. Density functional theory calculations of the model complex [Ru(Ph)(CO)(PH3)2]+ provided the structure shown on the right, which shows no ortho-CH···Ru interaction.
Is π-donation the only way? Unprecedented unsaturated Ru(II) species devoid of π-donor ligands
Heyn,Macgregor,Nadasdi,Ogasawara,Eisenstein,Caulton
, p. 5 - 26 (2008/10/08)
Reaction of RuHX(CO)L2 (L = PtBu2Me) with tBuLi in pentane or toluene at -40°C gives Ru(H)2(CO)L2 as a reactive and thermolabile square-pyramidal species with inequivalent hydrides (one apical). This molecule forms 1:1 adducts with N2, H2, PH2Ph, PHPh2 or PHCy2, and forms Ru(H)2(CO)2L2, then Ru(CO)3L2 with CO. Oxidative addition of the H-C bond of HC2Ph, the H-Si bonds of SiPh2H2 and SiMe3H and the H-O bond of H2O occurs with elimination of H2, to give RuH(C2Ph)(CO)L2, RuH(SiR3)(CO)L2 and RuH(OH)(CO)L2, respectively. Ru(H)2(CO)L2 reacts with MeI to give RuMeI(CO)L2 and RuHI(CO)L2. Above -40°C, Ru(H)2(CO)L2 hydrogenates isobutylene and subsequently metallates one tBu group of its phosphine, to give RuH(CO)L(P～C). This strained molecule reacts with arenes to give RuH(aryl)(CO)L2. Reaction of RuHCl(CO)L2 with PhLi provides an alternative synthesis of RuHPh(CO)L2, which rapidly ( ～2 h) exchanges its H and Ph groups with C6D6 or with toluene. Reaction of RuHPh(CO)L2 with CO gives the much less reactive RuH(Ph)(CO)2L2, while RuHPh(CO)L2 reacts with MeI to give RuMeI(CO)L2 and with EtBr to give first Ru(Et)Br(CO)L2, then RuHBr(CO)L2 and ethylene. N-chlorosuccinimide converts RuHPh(CO)L2 into RuClPh(CO)L2. On a timescale of 2 days, RuH(aryl)(CO)L2, in arene solvent, rearranges to Ru(η6-arene)(CO)L and free L. The structural and electronic properties of the family of unsaturated RuXH(CO)(PH3)2 (X = H, SiH3, CCH, F, Cl, Br, OH, OMe) complexes have been analyzed by core potential ab initio methods at the MP2 level. The preferred structure for each member of this family is calculated to be square-pyramidal with the strongest σ-donor ligand (H or SiH3) at the apical site. Powerful σ-donating groups (i.e., ligands with a strong trans influence: H or SiR3) are found to be very efficient at compensating the electron deficiency at the metal. A π-donating ligand occupies a basal site, trans to the CO group. Due to the lack of a low-lying empty metal dπ orbital (i.e., the molecule is a sigma Lewis acid), π effects are weaker at stabilizing the unsaturation: a push-pull interaction involving the p lone pair(s) of X, the occupied d metal orbital and the π* co orbitals constitutes an additional, but secondary, stabilizing factor. This explains why Ru(H)2(CO)L2 and RuH(SiR3)(CO)L2 are both observable species. The calculated Ru-N bond dissociation energy of RuXH(NH3)(CO)(PH3)2 confirms the dominant role of the σ-donation of the ligands, especially that of the ligand trans to NH3. Thus, compounds of the type RuH(X)(CO)(PR3)2 are better regarded as primarily 'σ-stabilized' 16-electron species whose properties are then finely tuned by π effects.
