Combinations of ethers and B(C6F5)3 function as hydrogenation catalysts.

It works ether way: Labile adducts of dialkyl ethers with the electrophilic borane B(C6F5)3 are shown to scramble HD to H2 and D2 and catalyze the hydrogenation of 1,1-diphenylethylene.

On the interaction of acetone with electrophilic metallocavitands having extended cavities.

We report the synthesis and characterization of tantalum-boronate trimetallic clusters of general formula {[Cp*Ta](3)(µ(2)-RB(O)(2))(3)(µ(2)-OH)(µ(2)-O)(2)(µ(3)-OH)} (R= 4-(C(6)H(5))(C(6)H(4)) (Ta(3)-4Ph), 4-(C(6)H(5)O)(C(6)H(4)) (Ta(3)-4OPh), 4-(C(7)H(7)O)(C(6)H(4)) (Ta(3)-4OBn), 4-(C(8)H(5))(C(6)H(4)) (Ta(3)-4PhEt), and 4-(C(12)H(7))(C(6)H(4)) (Ta(3)-4Napht)). All complexes have been characterized by NMR spectroscopy and X-ray diffraction. The trimetallic species feature a large Lewis acid type cavity allowing for substrate binding in both the solid and the liquid state using a unique electrostatic interaction and a hydrogen bond. ΔH° and ΔS° values for association of acetone with the complexes vary between -2.0 and -4.1 kcal·mol(-1) and -3 and 2 cal·mol(-1)·K(-1), respectively, showing weaker binding than smaller cavitands of the same type. The barrier for acetone exchange at equilibrium is similar for all complexes, and ΔH(‡) values vary between 8.2 and 11.4 kcal·mol(-1).

Synthesis and structure of indenyl rhodium(I) complexes containing unsaturated phosphines: catalyst precursors for alkene hydroboration.

The indenyl compound (eta(5)-C(9)H(7))Rh(coe)(2) (1, coe = cis-cyclooctene) has been prepared as a thermally stable alternative to the diethylene derivative (eta(5)-C(9)H(7))Rh(eta(2)-H(2)C[double bond, length as m-dash]CH(2))(2). Compound 1 reacts with unsaturated phosphines Ph(2)PR (R = CH[double bond, length as m-dash]CH(2), 2; CH(2)CH=CH(2), 3; and C triple bond C-tert-Bu, 4) to give complexes of the type (eta(5)-C(9)H(7))Rh(Ph(2)PR)(2), where bonding occurs through the phosphorus atom. Addition of Ph(2)PC triple bond CPPh(2) to 1 gave the dimer [(eta(5)-C(9)H(7))Rh(micro-Ph(2)PC triple bond CPPh(2))](2) (5). Solution and solid state data showed that these new phosphine complexes have only a moderate amount of distortion within the indenyl ring. These compounds were found to catalyse the hydroboration of vinylarenes and the first example of an internal hydroboration of diphenylvinylphosphine has been reported.

Structural study of acidic metallocavitands and characterization of their interactions with Lewis bases.

We report the synthesis and characterization of tantalum-boronate trimetallic clusters of the general formula {[Cp*Ta](3)(mu(2)-RB(O)(2))(3)(mu(2)-OH)(mu(2)-O)(2)(mu(3)-OH)} (R = i-Bu (Ta(3)-iBu), C(6)H(5) (Ta(3)-Ph), 2,5-(CH(3))(2)(C(6)H(3)) (Ta(3)-2,5Me), 3,5-(CH(3))(2)(C(6)H(3)) (Ta(3)-3,5Me), and 3,5-(CF(3))(2)(C(6)H(3)) (Ta(3)-3,5CF(3))). Three of these complexes feature a Lewis acid type cavity allowing for substrate binding in both the solid and the liquid state using a unique electrostatic interaction and a hydrogen bond. We also report the synthesis of {[Cp*Ta](2)(mu(2)-MesB(O)(2))(2)[MesB(OH)(O)](2)(mu(2)-OH)(2)} (Mes = 2,4,6-(CH(3))(3)C(6)H(2) (Ta(2)-Mes)). All complexes have been characterized by NMR and X-ray diffraction studies, and the steric and electronic effects on the boronate ligands have been investigated. The physical properties of the interaction between the tantalum-boronate clusters and tetrahydrofuran and acetone have been studied by thermogravimetric analysis, FT-IR, and Density Functional Theory calculations to characterize the molecular interactions in the resulting adducts.