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首页> 外文期刊>Dalton transactions: An international journal of inorganic chemistry >Rigid NON- and NSN-ligand complexes of tetravalent and trivalent uranium: Comparison of U-OAr _2 and U-SAr _2 bonding
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Rigid NON- and NSN-ligand complexes of tetravalent and trivalent uranium: Comparison of U-OAr _2 and U-SAr _2 bonding

机译:四价和三价铀的刚性非-和NSN-配体配合物:U-OAr _2和U-SAr _2键的比较

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摘要

A rigid NSN-donor proligand, 4,5-bis(2,6-diisopropylanilino)-2,7-di-tert- butyl-9,9-dimethylthioxanthene (H _2[TXA _2], 1) was prepared by palladium-catalyzed coupling of 2,6-diisopropylaniline with 4,5-dibromo-2,7-di-tert-butyl-9,9-dimethylthioxanthene. Deprotonation of 1 using ~nBuLi provided Li _2(DME) _2[TXA _2] (2), and subsequent reaction with UCl _4 afforded [Li(DME) _3][(TXA _2)UCl _3] (4). The analogous NON-donor ligated complex [(XA _2)UCl _3K(DME) _3] [3; XA _2 = 4,5-bis(2,6-diisopropylanilino)-2,7-di-tert-butyl-9,9- dimethylxanthene] was prepared by the reaction of K _2(DME) _x[XA _2] with UCl _4. A cyclic voltammogram (CV) of 3 in THF/[NBu _4][B(C _6F _5) _4] at 200 mV s ~(-1) showed an irreversible reduction to uranium(iii) at E _(pc) = -2.46 V versus FeCp _2 ~(0/+1), followed by a product wave at E _(1/2) = -1.83 V. Complex 4 also underwent irreversible reduction to uranium(iii) [E _(pc) = -2.56 V], resulting in an irreversible product peak at E _(pa) = -1.83 V. One-electron reduction of complexes 3 and 4 using K(naphthalenide) under an argon atmosphere in DME yielded 6-coordinate [(XA _2)UCl(DME)] (5) and the thermally unstable 7-coordinate [(TXA _2)U(DME)Cl _2Li(DME) _2] (6), respectively. The U-S distances in 4 and 6 are uncommonly short, the C-S-U angles are unusually acute, and the thioxanthene backbone of the TXA _2 ligand is significantly bent. By contrast, the xanthene backbone in XA _2 complexes 3 and 5 is planar. However, κ ~3- coordination and an approximately meridional arrangement of the ancillary ligand donor atoms is maintained in all complexes. DFT and Atoms in Molecules (AIM) calculations were carried out on 3, 4, 5, 6, [(XA _2)UCl _3] ~- (3B), [(TXA _2)UCl _2(DME)] ~- (6B) and [(TXA _2)UCl(DME)] (6C) to probe the extent of covalency in U-SAr _2 bonding relative to U-OAr _2 bonding.
机译:通过钯-制备了刚性的NSN供体配体4,5,5-双(2,6-二异丙基苯胺基)-2,7-二叔丁基-9,9-二甲基噻吨(H _2 [TXA _2],1)。 2,6-二异丙基苯胺与4,5-二溴-2,7-二叔丁基-9,9-二甲基噻吨的催化偶联。使用〜nBuLi使1去质子化,得到Li _2(DME)_2 [TXA _2](2),随后与UCl _4反应得到[Li(DME)_3] [(TXA _2)UC1 _3](4)。类似的非供体结扎复合物[(XA _2)UC1 _3K(DME)_3] [3;通过K _2(DME)_x [XA _2]与UCl的反应制备XA _2 = 4,5-双(2,6-二异丙基苯胺基)-2,7-二叔丁基-9,9-二甲基x吨] _4。在200 mV s〜(-1)下的THF / [NBu _4] [B(C _6F _5)_4]中3的循环伏安图(CV)在E _(pc)=-下不可逆地还原为铀(iii)。 2.46 V对FeCp _2〜(0 / + 1),然后在E _(1/2)= -1.83 V处产生产物波。配合物4也经历了不可逆还原为铀(iii)[E _(pc)=- 2.56 V],在E _(pa)= -1.83 V处产生不可逆的产物峰。在氩气中于DME中使用K(萘)进行配合物3和4的单电子还原得到6坐标[(XA _2) UCl(DME)](5)和热不稳定的7坐标[(TXA _2)U(DME)Cl _2Li(DME)_2](6)。在4和6中的U-S距离通常较短,C-S-U角度异常尖锐,并且TXA _2配体的噻吨蒽骨架显着弯曲。相比之下,XA _2配合物3和5中的backbone吨骨架是平面的。然而,在所有配合物中都维持了κ〜3-配位和辅助配体供体原子的子午线排列。 DFT和分子原子(AIM)的计算是在3、4、5、6,[(XA _2)UC1 _3]〜-(3B),[(TXA _2)UCl _2(DME)]〜-(6B )和[(TXA _2)UC1(DME)](6C)来研究U-SAr _2键相对于U-OAr _2键的共价程度。

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