名称:
π Complexes of Fluorous Alkynes, Cyclobutadienes, and Benzenes: Syntheses and Phase Properties of Cobalt and Chromium Tricarbonyl Adducts
摘要:
Reactions of Cr(CO)(6) and fluorous benzenes C6H6-x((CH2)(3)R-f8)(x) (x = a, 1; b, 2 (1,2); c, 2 (1,3); d, 2 (1,4); e, 3 (1,3,5); R-f8 = (CF2)(7)CF3; dibutyl ether, 140 degrees C) give the pi complexes (eta(6)-C6H6-x((CH2)(3)R-f8)Cr(CO)(3) (1a-e; 92-42%); p-R-f8(CH2)(3)C6H4CH(S(CH2)(3)Rf(8))(CH2)(2)R-f8 affords an analogous adduct (If; 47%). The CF3C6F11/toluene partition coefficients of 1a-f increase with the number of ponytails (three, 99:1 to 97:3; two, 91:9; one, 49:51); the fluorophilicities are only slightly less than a-f. The IR v(CO) values show any residual inductive effect of the perfluoroalkyl groups at chromium to be slight. The reaction of LiC equivalent to CSi(CH3)(3) and R-f8(CH2)(3)I gives the fluorous alkyne R-f8(CH2)(3)C CSi(CH3)(3) (2; 63%). Addition of wet n-Bu4N+ F- affords Rf(8)(CH2)(3)C equivalent to CH (71%), which upon treatment with t-BuLi and R-f8(CH2)(3)I yields R-f8(CH2)(3)C equivalent to C(CH2)(3)R-f8 (4; 58%). The reaction of 2 and CO2(CO)(8) gives the alkyne complex Co-2(CO)(6)(eta(2)-mu-R-f8(CH2)(3)CCSi(CH3)(3)) (88%). Reactions of 2 or 4 with (eta(5)-C5H5)CO(CO)(2) (2: 1, decane, 150-160 degrees C) give the pi cyclobutadiene complexes (eta(5)-C5H5)Co{eta(4)-C-4[Z](2)[(CH2)(3)R-f8](2)} (Z = Si(CH3)(3), 6, 70%; (CH2)(3)R-f8, 7, 32%). The CF3C6F11/toluene partition coefficients show 6 and 7 to be more fluorophilic than their precursors 2 and 4, despite the added (eta(5)-C5H5)CO groups.