82972-36-9Relevant academic research and scientific papers
Aryloxide ligands in the metathesis of olefins: Syntheses of W(OAr)xCl6-x complexes with x = 2, 3, and 4. Crystal structures of W(O-2,6-C6H3-i-Pr2)3Cl3 and W(O-2,6-C6H3Ph2)2Cl4
Quignard, Francoise,Leconte, Michel,Basset, Jean-Marie,Hsu, Leh-Yeh,Alexander, John J.,Shore, Sheldon G.
, p. 4272 - 4277 (2008/10/08)
Syntheses and characterization of three families of aryloxide complexes of W(VI), which are useful precursors for metathesis of olefins, are reported: W(OAr)x(Cl)6-x (x = 2, 3, 4). The structures of Cl3W(O-2,6-C6H3-i-Pr2)3 and Cl4W(O-2,6-C6H3Ph2)2 are described. Both complexes have slightly distorted octahedral coordination spheres. For the structure of Cl3W(O-2,6-C6H3-i-Pr2)3, the chlorines occupy the meridional sites, while in the case of Cl4W(O-2,6-C6H3Ph2)2, the OC6H3Ph2 groups are cis to each other. Crystal data for Cl3W(O-2,6-C6H3-i-Pr2)3: space group P21/n, monoclinic, a = 13.446 (2) ?, b = 17.824 (4) ?, c = 16.289 (3) ?, β = 99.55 (1)°, V = 3851 ?3, mol wt 882.02, ρcalcd = 1.418 g cm-3 for Z = 4. For Mo Kα 7164 unique reflections were collected at 298 K over the range 4° ≤ 20 ≤ 50° with 5582 reflections > 3σ(I) used in the final refinement. RF = 0.023 and RwF = 0.031. Crystal data for Cl4W(O-2,6-C6H3Ph2) 2·1/2C7H8: space group P1, triclinic, a = 10.547 (3) ?, b = 13.669 (1) ?, c = 14.632 (1) ?, α = 84.89 (2)°, β = 78.34 (1)°, γ = 83.48 (2)°, V = 2062 ?3, mol wt 816.26, ρcalcd = 1.317 g cm-3 for Z = 2. For Mo Kα 2915 reflections were collected at 298 K over the range 4° ≤ 2θ ≤ 40° with 2588 reflections ≥3σ(I) used in the final refinement. RF = 0.058 and RwF = 0.094.
Electrochemical behavior of tungsten(VI) aryloxides and catecholates
Beshouri, Sharon M.,Rothwell, Ian P.
, p. 1962 - 1964 (2008/10/08)
The electrochemical behavior of a number of tungsten(VI) aryloxides and catecholates has been investigated. For deep red octahedral W(OAr-Me)6 (OAr-Me = 4-methylphenoxide), two one-electron reduction waves are present in its cyclic voltammogram in THF with 0.2 M n-Bu4N+PF6- (TBAH) as a supporting electrolyte. The first wave is reversible both chemically and electrochemically while the second electron transfer is totally irreversible. In contrast, the use of chelating aryloxides gives compounds such as W(biph)3 (biph = 2,2′-biphenoxide) and W(t-Bu2cat)3 (t-Bu2cat = 3,5-di-tert-butylcatecholate), which exhibit reversibility for both the first and second electron-transfer steps. With the less bulky catecholates, 4-methyl- and 4-tert-butylcatecholate (Mecat and t-Bucat), the electrochemical data are consistent with these complexes existing as dimers in solution, W2(Mecat)6 and W2(t-Bucat)6. Reduction occurs to generate the mononuclear anions W(Mecat)3- and W(t-Bucat)3-, respectively. Although reoxidation of these anions initially produces neutral monomers, they rapidly dimerize to the thermodynamically favored dimers. Relatively stable derivatives of the tungsten(V) monoanions can be obtained with cobaltocene as reducing agent.
