Institut für Anorganische Chemie, Universität Göttingen, Tammannstrasse 4, 37077 Göttingen, Germany.
J Am Chem Soc. 2010 Jul 28;132(29):10164-70. doi: 10.1021/ja103988d.
Herein we report on the reaction of stable two-coordinate silylene, L(1)Si [L(1) = CH{(C=CH(2))(CMe)(2,6-iPr(2)C(6)H(3)N)(2)}] (1) and three-coordinate silylene (Lewis base stabilized silylene), L(2)SiCl [L(2) = PhC(NtBu)(2)] (2) with aromatic compounds containing C-F and C-H bonds. The reaction of 1 and 2 with hexafluorobenzene (C(6)F(6)) affords the silicon(IV) fluorides, L(1)SiF(C(6)F(5)) (3) and L(2)SiFCl(C(6)F(5)) (4), respectively. The reaction proceeds through the unprecedented oxidative addition of one of the C-F bonds to the silicon(II) center without any additional catalyst. When 1 and 2 are treated with octafluorotoluene (C(6)F(5)CF(3)), pentafluoropyridine (C(5)F(5)N) regioselective C-F bond activation occurs leading to the formation of L(1)SiF(4-C(6)F(4)CF(3)) (5), L(1)SiF(4-C(5)F(4)N) (6), L(2)SiFCl(4-C(6)F(4)CF(3)) (7), and L(2)SiFCl(4-C(5)F(4)N) (8), respectively. More interestingly, compounds 1 and 2 react with pentafluorobenzene (C(6)F(5)H) under formation of silicon(IV) hydride L(1)SiH(C(6)F(5)) (9) by chemoselective C-H bond activation, in the latter case producing silicon(IV) fluoride L(2)SiFCl(4-C(6)F(4)H) (10) by chemo- as well as regioselective C-F bond activation. Furthermore, the reaction of 1 with 1,3,5-trifluorobenzene (1,3,5-C(6)F(3)H(3)) leads to the chemoselective formation of silicon(IV) hydride L(1)SiH(1,3,5-C(6)F(3)H(2)) (11). The formation of compounds 9 and 11 occurs via oxidative addition of the aromatic C-H bond to the silicon(II) center instead of C-F bond activation. All reported reactions proceed without any additional catalyst. Compounds 3, 4, 5, 6, 7, 8, 9, 10, and 11 were investigated by microanalysis and multinuclear NMR spectroscopy and compounds 3, 7, 8, and 9 additionally by single crystal X-ray structural analyses.
本文报道了稳定的二配位硅烯 L(1)Si [L(1) = CH{(C=CH(2))(CMe)(2,6-iPr(2)C(6)H(3)N)(2)}] (1) 和三配位硅烯 (路易斯碱稳定的硅烯) L(2)SiCl [L(2) = PhC(NtBu)(2)] (2) 与含有 C-F 和 C-H 键的芳族化合物的反应。1 和 2 与六氟苯 (C(6)F(6)) 的反应分别得到硅(IV)氟化物 L(1)SiF(C(6)F(5)) (3) 和 L(2)SiFCl(C(6)F(5)) (4)。该反应通过前所未有的 C-F 键中一个键对硅(II)中心的氧化加成进行，而无需任何额外的催化剂。当 1 和 2 与全氟甲苯 (C(6)F(5)CF(3)) 或五氟吡啶 (C(5)F(5)N) 接触时，会发生区域选择性 C-F 键活化，导致形成 L(1)SiF(4-C(6)F(4)CF(3)) (5)、L(1)SiF(4-C(5)F(4)N) (6)、L(2)SiFCl(4-C(6)F(4)CF(3)) (7) 和 L(2)SiFCl(4-C(5)F(4)N) (8)。更有趣的是，化合物 1 和 2 在形成硅(IV)氢化物 L(1)SiH(C(6)F(5)) (9) 时通过化学选择性 C-H 键活化与五氟苯 (C(6)F(5)H) 反应，在后一种情况下通过化学和区域选择性 C-F 键活化生成硅(IV)氟化物 L(2)SiFCl(4-C(6)F(4)H) (10)。此外，1 与 1,3,5-三氟苯 (1,3,5-C(6)F(3)H(3)) 的反应导致硅(IV)氢化物 L(1)SiH(1,3,5-C(6)F(3)H(2)) (11) 的化学选择性形成。化合物 9 和 11 的形成是通过芳族 C-H 键对硅(II)中心的氧化加成而不是 C-F 键活化进行的。所有报道的反应均无需任何额外的催化剂即可进行。通过微量分析和多核 NMR 光谱法研究了化合物 3、4、5、6、7、8、9、10 和 11，化合物 3、7、8 和 9 还通过单晶 X 射线结构分析进行了研究。
