Oxidation of Dihydrogen by Iridium Complexes of Redox-Active Ligands
Oxidation of Dihydrogen by Iridium Complexes of Redox-Active Ligands
复制标题
DOI：
10.1021/om9010593
复制
发表时间：
2010-04-26
期刊：
影响因子：
2.8
通讯作者：
Wilson, Scott R.
中科院分区：
文献类型：
--
作者：
Ringenberg, Mark R.;Nilges, Mark J.;Wilson, Scott R.
用2-（2-三氟甲基）氨基-4,6-二叔丁基苯酚(H(2)（t)BA(F)）和2-叔丁基氨基-4,6-二叔丁基苯酚(H(2)（t)BA(tBu)）衍生的偕胺酚酸酯配体制备了不饱和有机铱配合物。表征了以下16e配合物：Cp*M((t)BA(R), M = Ir (1(F)和1(t- bu)), Rh （2(F)）和（花香烃）Ru((t)BA(F)) （3(F)）。这些配合物在大约0和-0.25 V的电位下对Cp2Fe0/+进行两次1e氧化。δ E-1/2的大小对反阴离子很敏感，而可逆性受到路易斯碱的强烈影响，路易斯碱能稳定氧化衍生物。晶体学测量表明，氧化后的偕酚酸酯配体具有醌类特征，如苯基环主链中C- C键长度的变化增加和C- n和C-o键的缩短所表明的那样。与电荷中性前驱体不同，阳离子[Cp*M((t)BA(R))]（+）是路易斯酸，并与PR3 （R = Me, Ph）、CN-、MeCN（可逆）和CO形成表征良好的加合物。在没有竞争配体的情况下，阳离子氧化H-2。库仑测量结果表明，H2被单位制[Cp*M((t)BA(R))]（+）氧化，而不是相应的单位制。在生成[Cp*M((t)BA(R))]（+）所需的电位下，H-2在非配位碱的存在下发生催化氧化。率降低的顺序(Cp * M ((t) BA (F))] BAr4F > (Cp * M ((t) BA (F))] PF6 > (Cp * M ((t) BA (t-Bu))] PF6。Cp*M(（t)BA(R)）催化H-2还原二茂铁。
Unsaturated organoiridium complexes were prepared with amidophenolate ligands derived from 2-(2-trifluoromethyl)amino-4,6-di-tert-butylphenol (H(2)(t)BA(F)) and 2-tert-butylamino-4,6-di-tert-butylphenol (H(2)(t)BA(tBu)). The following 16e complexes were characterized: Cp*M((t)BA(R)) with M = Ir (1(F) and 1(t-Bu)), Rh (2(F)), and (cymene)Ru((t)BA(F)) (3(F)). These complexes undergo two 1e oxidations at potentials of about 0 and -0.25 V vs Cp2Fe0/+. The magnitude of Delta E-1/2 is sensitive to the counteranions, and the reversibility is strongly affected by the presence of Lewis bases, which stabilize the oxidized derivatives. Crystallographic measurements indicate that upon oxidation the amidophenolate ligands adopt quinoid character, as indicated by increased alternation of the C C bond lengths in the phenylene ring backbone and shortened C-N and C-o bonds. Unlike the charge-neutral precursors, the cationic [Cp*M((t)BA(R))](+) are Lewis acidic and form well-characterized adducts with PR3 (R = Me, Ph), CN-, MeCN (reversibly), and CO. In the absence of competing ligands, the cations oxidize H-2. Coulommetry measurements indicate that H2 is oxidized by the monocations [Cp*M((t)BA(R))](+), not the corresponding dications. Oxidation of H-2 is catalytic in the presence of a noncoordinating base at potentials required for the generation of [Cp*M((t)BA(R))](+). The rate decreases in the order [Cp*M((t)BA(F))]BAr4F > [Cp*M((t)BA(F))]PF6 > [Cp*M((t)BA(t-Bu))]PF6. The reduction of ferrocenium by H-2 is catalyzed by Cp*M((t)BA(R)).