标题：C-Cl bond activation of ortho-chlorinated benzamides by nickel and cobalt compounds supported with phosphine ligands
作者：Li, Junye; Wang, Chenggen; Li, Xiaoyan; Sun, Hongjian
作者机构：[Li, Junye; Wang, Chenggen; Li, Xiaoyan; Sun, Hongjian] Shandong Univ, Sch Chem & Chem Engn, Jinan 250100, Peoples R China.
通讯作者地址：[Sun, HJ]Shandong Univ, Sch Chem & Chem Engn, Shanda Nanlu 27, Jinan 250100, Peoples R China.
摘要：The C-Cl bonds of ortho-chlorinated benzamides Cl-ortho-C6H4C(=O)NHR (R = Me (1), nBu (2), Ph (3), (4-Me) Ph (4) and (4-Cl)Ph (5)) were successfully activated by tetrakis(trimethylphosphine) nickel(0) and tetrakis(trimethylphosphine) cobalt(0). The four-coordinate nickel(II) chloride complexes trans[( C6H4C(=O)NHR)Ni(PMe3)(2)Cl] (R = Me (6), nBu (7), Ph (8) and (4-Me) Ph (9)) as C-Cl bond activation products were obtained without coordination of the amide groups. In the case of 2, the ionic penta-coordinate cobalt(II) chloride [(C6H4C(=O)NHnBu)Co(PMe3)(3)]Cl (10) with the [C-phenyl, O-amide]-chelate coordination as the C-Cl bond activation product was isolated. Under similar reaction conditions, for the benzamides 3-5, hexa-coordinate bis-chelate cobalt(III) complexes (C6H4C(=O)NHR)Co-(Cl-ortho-C6H4C(=O)NR)(PMe3)(2) (11-13) were obtained via the reaction with [Co(PMe3)(4)]. Complexes 11-13 have both a five-membered [C,N]-coordinate chelate ring and a four-membered [N,O]-coordinate chelate ring with two trimethyphosphine ligands in the axial positions. Phosphonium salts [Me3P+-ortho-C6H4C(=O)NHR]Cl- (R = Ph (14) and (4-Me) Ph (15)) were isolated by reaction of complexes 8 and 9 as a starting material under 1 bar of CO at room temperature. The crystal and molecular structures of complexes 6, 7 and 9-12 were determined by single-crystal X-ray diffraction.