Department of Chemistry, University of California, Davis, One Shields Avenue, Davis, California 95616, United States.
Inorg Chem. 2012 Feb 6;51(3):1821-6. doi: 10.1021/ic202116s. Epub 2012 Jan 19.
Reduction of (3,5-(i)Pr(2)-Ar*)Co(μ-Cl) (3,5-(i)Pr(2)-Ar* = -C(6)H-2,6-(C(6)H(2)-2,4,6-(i)Pr(3))(2)-3,5-(i)Pr(2)) with KC(8) in the presence of various arene molecules resulted in the formation of a series of terphenyl stabilized Co(I) half-sandwich complexes (3,5-(i)Pr(2)-Ar*)Co(η(6)-arene) (arene = toluene (1), benzene (2), C(6)H(5)F (3)). X-ray crystallographic studies revealed that the three compounds adopt similar bonding schemes but that the fluorine-substituted derivative 3 shows the strongest cobalt-η(6)-arene interaction. In contrast, C-F bond cleavage occurred when the analogous reduction was conducted in the presence of C(6)F(6), affording the salt K[(3,5-(i)Pr(2)-Ar*)Co(F)(C(6)F(5))] (4), in which there is a three-coordinate cobalt complexed by a fluorine atom, a C(6)F(5) group, and the terphenyl ligand Ar*-3,5-(i)Pr(2). This salt resulted from the formal insertion of a putative 3,5-(i)Pr(2)-Ar*Co species as a neutral or anionic moiety into one of the C-F bonds of C(6)F(6). Reduction of (3,5-(i)Pr(2)-Ar*)Co(μ-Cl) in the presence of bulkier substituted benzene derivatives such as mesitylene, hexamethylbenzene, tert-butylbenzene, or 1,3,5-triisopropylbenzene did not afford characterizable products.
(3,5-(i)Pr(2)-Ar*)Co(μ-Cl)（3,5-(i)Pr(2)-Ar* = -C(6)H-2,6-(C(6)H(2)-2,4,6-(i)Pr(3))(2)-3,5-(i)Pr(2)）与 KC(8)在各种芳烃分子存在下的还原反应生成了一系列三联苯稳定的 Co(I)半夹心配合物(3,5-(i)Pr(2)-Ar*)Co(η(6)-arene)（芳烃=甲苯(1)，苯(2)，C(6)H(5)F(3)）。X 射线晶体学研究表明，这三种化合物采用相似的键合方案，但氟取代衍生物 3 显示出最强的钴-η(6)-芳烃相互作用。相比之下，当类似的还原反应在 C(6)F(6)存在下进行时，C-F 键发生断裂，生成盐 K[(3,5-(i)Pr(2)-Ar*)Co(F)(C(6)F(5))]（4），其中存在一个由一个氟原子、一个 C(6)F(5)基团和三联苯配体 Ar*-3,5-(i)Pr(2)配位的三配位钴配合物。该盐是由一个假定的 3,5-(i)Pr(2)-Ar*Co 物种作为中性或阴离子部分插入 C(6)F(6)的一个 C-F 键中形成的。(3,5-(i)Pr(2)-Ar*)Co(μ-Cl)在更庞大的取代苯衍生物（如均三甲苯、六甲基苯、叔丁基苯或 1,3,5-三异丙基苯）存在下的还原反应没有得到可表征的产物。
