219627-13-1Relevant articles and documents
Nonchelated alkene and alkyne complexes of d0 zirconocene pentafluorophenyl cations
Stoebenau III, Edward J.,Jordan, Richard F.
, p. 8638 - 8650 (2007/10/03)
This paper describes the generation and properties of nonchelated d 0 zirconocene-aryl-alkene and alkyne adducts that are stabilized by the presence of β-SiMe3 substituents on the substrates and the weak nucleophilicity of the -C6F5 ligand. The cationic complexes [(C5H4R)2Zr(C6F 5)][B(C6F5)4] (4a: R = H, 4b: R = Me) were generated by methide abstraction from (C5H 4R)2Zr(C6F5)Me by Ph 3C+. NMR studies show that 4a,b contain an o-CF...Zr dative interaction and probably coordinate a PhCl molecule in PhCl solution. Addition of allyltrimethylsilane (ATMS) to 4a,b in C6D5Cl solution at low temperature produces an equilibrium mixture of (C 5H4R)2Zr(C6F5)(H 2C=CHCH2SiMe3)+ (7a,b), 4a,b, and free ATMS. Similarly, addition of propargyltrimethylsilane (PTMS) to 4a produces an equilibrium mixture of Cp2Zr(C6F5)(HC= CCH2SiMe3)+ (8a), 4a, and free PTMS. The NMR data for 7a,b,and 8a are consistent with highly unsymmetrical substrate coordination and substantial polarization of the substrate multiple bond with significant positive charge buildup at Cint and negative charge buildup at Cterm. PTMS binds to 4a more strongly than ATMS does. The ATMS adducts undergo nondissociative alkene face exchange ("alkene flipping"), i.e., exchange of the (C5H4R) 2Zr(C6F5)+ unit between the two alkene enantiofaces without decomplexation of the alkene, on the NMR time scale.
Synthesis of the diborylated ferrocene 1,1′-bis-(bis-pentafluorophenylboryl)ferrocene and the X-ray structure of its trimethylphosphine adduct
Carpenter,Piers,McDonald
, p. 291 - 295 (2007/10/03)
The diborylated ferrocene compound 1,1′-Fc[B(C6F5)2]2 (2) was prepared via a transmetallation reaction involving 1,1′-Fc(HgCl)2 and two equivalents of ClB(C6F5)2. Although this reaction is very clean spectroscopically, isolated yields of 2 were never greater than 40% owing to the high solubility of the compound in non-donor solvents. Compound 2 is similar in its properties to the related monoborylated complex FcB(C6F5)2 (1) reported previously, particularly the UV-vis spectrum, which exhibits an intense charge transfer absorption (λmax = 233 nm, ε = 1.64 × 104) assignable to an Fedz2/dx2-y2 → Bp transition. However, 2, is significantly more Lewis acidic than 1, reacting with weak donors such as acetonitrile at room temperature, and effecting methide abstraction from Cp2ZrMe2 under mild conditions. Complex 2 also forms a bis(trimethylphosphine) adduct (3), which was structurally characterized via X-ray crystallography.
