Synthesis and Reactions of 3d Metal Complexes with the Bulky Alkoxide Ligand [OCtBu2Ph]

Treatment of NiCl2(dme) and NiBr2(dme) (dme = dimethoxyethane) with 2 equiv of LiOR (OR = OCtBu2Ph) forms the distorted trigonal planar complexes [NiLiX­(OR)2(THF)2] (THF = tetrahydrofuran) 5 (X = Cl) and 6 (X = Br). The reaction of CuX2 (X = Cl, Br) with 2 equiv of LiOR affords the Cu­(I) product Cu4(OR)4 (7). The same product can be obtained using the Cu­(I) starting material CuCl. NMR studies indicated that the reduction of Cu­(II) to Cu­(I) is accompanied by the oxidation of the alkoxide RO– to form the alkoxy radical RO•, which subsequently forms tert-butyl phenyl ketone by β-scission. Treatment of compounds 1–4 ([M2Li2Cl2(OR)4], M = Cr–Co) with thallium hexafluorophosphate allowed the isolation of the distorted tetrahedral complexes of the form M­(OR)2(THF)2 for M = Mn (8), Fe (9), and Co (10). Cyclic voltammetry performed on compounds 8–10 demonstrated irreversible oxidations for all complexes, with the iron complex 9 being the most reducing. Complex 9 shows a reactivity toward PhIO and Ph3SbS to form the corresponding dinuclear iron­(III) complexes Fe2(O)­(OR)4(THF)2 (11) and Fe2(S)­(OR)4(THF)2 (12), respectively. X-ray structural studies were performed, showing that the Fe–O–Fe angle for complex 11 is 176.4(1)° and that the Fe–S–Fe angle for complex 12 is 164.83(3)°.将二氯(二甲氧基乙烷（dimethoxyethane，缩写dme）)合镍(II) [NiCl₂(dme)] 与二溴(二甲氧基乙烷（dimethoxyethane，缩写dme）)合镍(II) [NiBr₂(dme)] 与2当量的烷氧基锂LiOR（其中OR = OCtBu₂Ph）反应，可生成扭曲三角平面型配合物[NiLiX(OR)₂(四氢呋喃（tetrahydrofuran，缩写THF）)₂]，对应产物5（X=Cl）与6（X=Br）。将卤化铜(II) CuX₂（X=Cl、Br）与2当量的LiOR反应，可获得铜(I)产物Cu₄(OR)₄（7）；使用氯化亚铜CuCl作为起始原料，同样可得到该产物。核磁共振（NMR）研究表明，铜(II)被还原为铜(I)的过程中，醇盐RO⁻会被氧化为烷氧基自由基RO•，后者随后通过β-裂解生成叔丁基苯基酮。对配合物1~4（[M₂Li₂Cl₂(OR)₄]，M=铬至钴）采用六氟磷酸铊进行处理，可分离得到通式为M(OR)₂(THF)₂的扭曲四面体配合物，对应金属分别为锰(8)、铁(9)与钴(10)。对配合物8~10进行循环伏安法测试，结果显示所有配合物均存在不可逆氧化过程，其中铁配合物9的还原性最强。配合物9可与亚碘酰苯（PhIO）、三苯基硫化锑（Ph₃SbS）发生反应，分别生成对应的双核铁(III)配合物Fe₂(O)(OR)₄(THF)₂（11）与Fe₂(S)(OR)₄(THF)₂（12）。X射线晶体结构分析显示，配合物11的Fe-O-Fe键角为176.4(1)°，配合物12的Fe-S-Fe键角为164.83(3)°。