97186-70-4Relevant articles and documents
Late to the Party: Synthesis and Characterization of Tellurium and Selenium Half-Sandwich Complexes
Bart, Suzanne C.,Jones, Leighton O.,Kieser, Jerod M.,Schatz, George C.,Uible, Madeleine C.,Zeller, Matthias
supporting information, p. 4104 - 4109 (2021/12/17)
We report the synthesis and characterization of the first series of tellurium and selenium complexes featuring an ν5-cyclopentadienyl ligand. Reaction of Ph3TeX (X = Cl, S2CNEt2) with MCpR (M = Li, K; R = H, Me4, Me5) results in high yields of [Cp][TePh3] (1), [CpMe4][TePh3] (2), and [Cp*][TePh3] (3), respectively. Similarly, reaction of Ph3SeCl with LiCp and KCp? furnishes [Cp][SePh3] (4) and [Cp*][SePh3] (5). Each was characterized by X-ray crystallography, revealing similar ν5-coordination with little distortion from an idealized half-sandwich geometry, presumably from the remaining lone pair on tellurium and selenium. The Te-centroid distances are relatively long (1: 2.770(3), 2: 2.746(1), and 3: 2.733(1) ?), suggesting a mostly ionic interaction. Se-centroid distances (4: 2.748(3), 5: 2.707(2), 2.730(2) ?) were found to be surprisingly similar despite its smaller atomic radius. Compounds 2, 3, and 5 display rapid decomposition at room temperature, extruding a phenylated cyclopentadiene and the respective diphenylchalcogenide. The nature of bonding within these complexes was investigated through DFT methods and found to be primarily ionic in nature.
Organolanthanide and organoactinide oxidative additions exhibiting enhanced reactivity. 5. Stoichiometry, kinetic, and mechanistic studies of (C5Me5)2YbII·OEt2 oxidative-addition reactions and of (C5Me5)2YbIIIR (R = R, X) YbIII ...
Finke,Keenan,Watson
, p. 263 - 277 (2008/10/08)
Full title: Organolanthanide and organoactinide oxidative additions exhibiting enhanced reactivity. 5. Stoichiometry, kinetic, and mechanistic studies of (C5Me5)2YbII·OEt2 oxidative-addition reactions and of (C5Me5)2YbIIIR (R = R, X) YbIII-Grignard reactions with alkyl and aryl halides. Evidence for the dominance of inner-sphere mechanisms. (C5Me5)2YbII·OEt 2 undergoes atom-abstraction oxidative addition with alkyl and aryl halides according to the generalized stoichiometry 1.0(C5Me5)2YbII·OEt 2 + (1 + a)RX → (1 - a)(C5Me5)2YbIIIX + (a)(C5Me5)1YbIIIX2 + (a)C5Me5R + 1.0Et2O + 1.0[R-R, R-H(alkanes), R(-H)(olefins)]. A reactive Yb-alkyl intermediate, (C5Me5)2YbIIIR, is formed from R? trapping by diamagnetic (C5Me5)2YbII. This (C5Me5)2YbIIIR intermediate and the initial product (C5Me5)2YbIIIX react further with RX in subsequent YbIII-Grignard reactions that are retarded by added Et2O and, therefore, apparently operate via an inner-sphere pathway. The observed YbIII-Grignard stoichiometries are (C5Me5)2YbIIIR + 2RX → (C5Me5)2YbIIIX2 + C5Me5R + R-R and (C5Me5)2YbIIIX + RX → (C5Me5)1YbIIIX2 + C5Me5R. The absolute rates of reaction of RX with (C5Me5)2YbII·OEt2 are found to be first-order each in (C5Me5)2YbII·OEt-2 and RX, with an added inverse dependence upon Et2O. The Et2O dependence is consistent with a requirement for a site of coordinative unsaturation and an inner-sphere pathway. Comparison of the rates of reactions of (C5Me5)2UIII(Cl)(THF) and (C5Me5)2YbII·OEt2 with RX provides compelling evidence for participation of electron transfer in these net atom-abstraction reactions.
