New Benzylpotassium Reagents and Their Utility for the Synthesis of Homoleptic Uranium(IV) Benzyl Derivatives

A new
family of benzylpotassium reagents, KBn′(1-Bn′)
(Bn′ = p-iPrBn, p-tBuBn, p-NMe2Bn, p-SMeBn, m-OMeBn, o-OMeBn, 2-picolyl), was synthesized using
a modified literature procedure and characterized by multinuclear
NMR spectroscopy. Combining four equivalents of 1-Bn′
with UCl4 at low temperature in THF afforded the homoleptic
uranium­(IV) derivatives 2-Bn′ (2-p-iPr, 2-p-tBu, 2-p-NMe2, 2-p-SMe, 2-o-Picolyl, 2-m-OMe, 2-o-OMe). In addition to 1H
NMR spectroscopic characterization, structural studies of five of
these organouranium compounds (2-p-iPr, 2-p-tBu, 2-o-Picolyl, 2-m-OMe, 2-o-OMe) were performed, showing that in many cases the benzyl groups are
coordinated in an η4-fashion, lending stability to
these otherwise low-coordinate molecules. In the cases of U­(o-OMeBn)4 (2-o-OMe) and U­(2-picolyl)4 (2-o-Picolyl), heteroatom
coordination to the uranium center is observed.

一种新型的苄基钾试剂家族，KBn′（1-Bn′，其中Bn′分别为p-iPrBn、p-tBuBn、p-NMe2Bn、p-SMeBn、m-OMeBn、o-OMeBn、2-picolyl），经改进文献方法合成，并通过多核核磁共振波谱进行表征。在低温下，将1-Bn′与UCl4以四当量比在THF中混合，得到了同配的铀(IV)衍生物2-Bn′（2-p-iPr、2-p-tBu、2-p-NMe2、2-p-SMe、2-o-Picolyl、2-m-OMe、2-o-OMe）。除了进行1H核磁共振波谱表征外，还对其中五种有机铀化合物（2-p-iPr、2-p-tBu、2-o-Picolyl、2-m-OMe、2-o-OMe）的结构进行了研究，结果表明，在许多情况下，苄基以η4方式与铀原子配位，从而赋予这些原本低配位分子以稳定性。在U(o-OMeBn)4（2-o-OMe）和U(2-picolyl)4（2-o-Picolyl）的情况下，观察到铀中心与杂原子的配位。