Das Uttam K, Daifuku Stephanie L, Iannuzzi Theresa E, Gorelsky Serge I, Korobkov Ilia, Gabidullin Bulat, Neidig Michael L, Baker R Tom
Department of Chemistry and Biomolecular Sciences and Centre for Catalysis Research and Innovation, University of Ottawa , Ottawa, Ontario K1N 6N5, Canada.
Department of Chemistry, University of Rochester , Rochester, New York 14627, United States.
Inorg Chem. 2017 Nov 20;56(22):13766-13776. doi: 10.1021/acs.inorgchem.7b01802. Epub 2017 Nov 7.
We report an easily prepared bis(thioether) amine ligand, SNS, along with the synthesis, characterization, and reactivity of the paramagnetic iron(II) bis(amido) complex, [Fe(κ-SNS)] (1). Binding of the two different thioethers to Fe generates both five- and six-membered rings with Fe-S bonds in the five-membered rings (av 2.54 Å) being significantly shorter than those in the six-membered rings (av 2.71 Å), suggesting hemilability of the latter thioethers. Consistent with this hypothesis, magnetic circular dichroism (MCD) and computational (TD-DFT) studies indicate that 1 in solution contains a five-coordinate component [Fe(κ-SNS)(κ-SNS)] (2). This ligand hemilability was demonstrated further by reactivity studies of 1 with 2,2'-bipyridine, 1,2-bis(dimethylphosphino)ethane, and 2,6-dimethylphenyl isonitrile to afford iron(II) complexes [LFe(κ-SNS)] (3-5). Addition of a Brønsted acid, HNTf, to 1 produces the paramagnetic, iron(II) amine-amido cation, Fe(κ-SNS)(κ-SNS) (6; Tf = SOCF). Cation 6 readily undergoes amine ligand substitution by triphos, affording the 16e complex Fe(κ-SNS)(κ-triphos) (7; triphos = bis(2-diphenylphosphinoethyl)phenylphosphine). These complexes are characterized by elemental analysis; H NMR, Mössbauer, IR, and UV-vis spectroscopy; and single-crystal X-ray diffraction. Preliminary results of amine-borane dehydrogenation catalysis show complex 7 to be a selective and particularly robust precatalyst.
我们报道了一种易于制备的双（硫醚）胺配体SNS，以及顺磁性铁（II）双（酰胺）配合物[Fe(κ-SNS)]（1）的合成、表征及反应活性。两种不同的硫醚与铁结合形成了五元环和六元环，五元环中的Fe-S键（平均键长2.54 Å）明显短于六元环中的Fe-S键（平均键长2.71 Å），这表明后者硫醚具有半活性。与该假设一致，磁圆二色性（MCD）和计算（TD-DFT）研究表明，溶液中的1含有五配位组分[Fe(κ-SNS)(κ-SNS)]（2）。通过1与2,2'-联吡啶、1,2-双（二甲基膦基）乙烷和2,6-二甲基苯基异腈的反应研究进一步证明了这种配体的半活性，得到了铁（II）配合物[LFe(κ-SNS)]（3 - 5）。向1中加入布朗斯特酸HNTf会生成顺磁性的铁（II）胺-酰胺阳离子Fe(κ-SNS)(κ-SNS)（6；Tf = SOCF）。阳离子6很容易被三膦进行胺配体取代，得到16电子配合物Fe(κ-SNS)(κ-三膦)（7；三膦 = 双（2-二苯基膦基乙基）苯基膦）。这些配合物通过元素分析、1H NMR、穆斯堡尔谱、红外光谱和紫外-可见光谱以及单晶X射线衍射进行表征。胺-硼烷脱氢催化的初步结果表明配合物7是一种选择性且特别稳定的前催化剂。
