A broad range of benzaldimines and ketimines can be hydrosilated efficiently, employing B(C(6)F(5))(3) as a catalyst in conjunction with PhMe(2)SiH. Spectral evidence supports the intermediacy of a silyliminium cation with a hydridoborate counterion formed via abstraction of a hydride from PhMe(2)SiH by B(C(6)F(5))(3) in the presence of imines.

The commercially available borane tris(pentafluorophenyl)borane, B(C(6)F(5))(3), is an effective catalyst for the dehydrogenative silation of alcohols using a variety of silanes, R(3)SiH, R(2)SiH(2), and R(2)R'SiH. Generally, the reactions occur in a convenient time frame at room temperature using 2 mol % of the borane and are clean and high yielding, with dihydrogen as the only byproduct. Primary aliphatic alcohols are silated cleanly but slowly, with reaction times ranging from 20 to 144 h. Faster reaction times can be achieved by increasing the catalyst loading to 8 mol % or by heating the reaction to approximately 60 degrees C. Secondary and tertiary alcohols react more rapidly, with most reactions being complete in 0.5-2 h. The reaction is tolerant of many functional groups including C=C, C&tbd1;C, -Br, aliphatic ketones, C(O)OR, lactones, furans, OBn, OMe, and NO(2); examples of each are given. Using the phenolic substrate 2,4,6-trimethylphenol, a number of different silanes were tested. Only the most bulky silanes (Bn(3)SiH and Pr(i)()(3)SiH) were not reactive under these conditions. The selectivity of the silation reactions are roughly governed by the relative basicity of the alcohols (and other functions in the molecule) with more basic groups being selectively silated. These observations are rationalized on the basis of a mechanism that invokes borane activation of the silane by hydride abstraction. The resulting intermediate silylium/hydridoborate ion pair then reacts with alcohols to give the observed silyl ether and dihydrogen products.

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The reactions of AlMe3, BEt3, and ZnEt2 with toluene solutions of the copper(II) complexes [CuL2] {L = acetylacetonate (acac; 1), hexafluoroacetylacetonate (hfac; 2), N-isopropyl-β-ketiminate (acnac; 3), N,N-dimethyl-β-diketiminate (nacnac; 4), 2-pyrrolylaldehyde (PyrAld; 5), N-isopropyl-2-pyrrolylaldiminate (PyrIm iPr; 6a), N-ethyl-2-pyrrolylaldiminate (PyrImEt; 6b), and N-isopropyl-2-salicylaldiminate (IPSA; 7)} were investigated, and most combinations were found to deposit metal films or metal powder at 50 °C or less. SEM and XPS of metal films deposited on ruthenium showed a range of morphologies and compositions, including pure copper (excluding oxygen content after atmospheric exposure). These nonaqueous solution screening studies provided a rapid and convenient means to identify the most promising [CuIIL2] precursor/ER n co-reagent combinations for copper metal ALD/pulsed-CVD studies, and subsequent ALD/pulsed-CVD studies were performed using 6b in combination with AlMe3, BEt3 and ZnEt2. As in solution, the reactivity of these reagents (pulsed-CVD) followed the order ZnEt2 ≈ AlMe3 ≫ BEt3. Furthermore, at 120−150 °C, ZnEt2 was used successfully to deposit smooth, conductive films composed of copper with 8−15% Zn. On the basis of CVD studies with ZnEt2, zinc content appears to derive from a parasitic CVD process, which becomes more favorable above 120 °C, detracting from the goal of self-limiting deposition.

Adducts of the N-benzyl imines Ph(R)CNBn (R = Ph, CH3, H) and t Bu(CH3)CNBn and the N-phenyl imine Ph(H)CNPh with the Lewis acid tris(pentafluorophenyl)borane, B(C6F5)3, have been prepared and characterized in solution and in the solid state. For each imine, the Lewis acid is N-bound, with the exception of the sterically demanding base t Bu(CH3)CNBn, which reacts with B(C6F5)3 through its enamine tautomer to form an α-C bound adduct, 5. In the N-bound imine−borane adducts 1−4, steric crowding and π-stacking between C6F5 and C6H5 rings results in restricted rotation about the B−N and B−C bonds; the dynamic behavior which results can be studied using variable-temperature 19F and 1H NMR spectroscopy. For the unsymmetrical ketimines and aldimines, kinetic adducts of the thermodynamically dominant free imine are observed to form initially upon treatment with B(C6F5)3; these adducts slowly convert thermally to the thermodynamic adducts of the less stable imine. For the ketimine Ph(CH3)CNBn, both the kinetic adduct 2-k and the thermodynamic adduct 2-t were fully characterized. In the solid-state structures of all the adducts except 5, one or two C6F5/C6H5 stacking interactions are present; in one case, the adduct 3-t between B(C6F5)3 and Ph(H)CNBn, intermolecular stacking interactions are apparent in the crystal-packing diagram. The implications of the structures of these adducts for Lewis acid mediated addition of nucleophiles to imines is discussed.