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首页> 外文期刊>Dalton transactions: An international journal of inorganic chemistry >Stable divalent germanium, tin and lead amino- (ether)-phenolate monomeric complexes: structural features, inclusion heterobimetallic complexes, and ROP catalysis?
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Stable divalent germanium, tin and lead amino- (ether)-phenolate monomeric complexes: structural features, inclusion heterobimetallic complexes, and ROP catalysis?

机译：稳定的二价锗，锡和氨基（醚）-苯酚铅铅酸酯单体配合物：结构特征，包含的异双金属配合物和ROP催化？

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摘要

Stable germanium(II) and lead(II) amido complexes {LO~i}M(N(SiMe_3)_2) (M= Ge~(II), Pb~(II)) bearing amino(ether)- phenolate ligands are readily available using the proteo-ligands {LOi}H of general formula 2-CH_2NR_2-4,6- ~tBu_2-C_6H_2OH (i = 1, NR_2 = N((CH_2)_2OCH_3)_2; i = 2, NR_2 = NEt_2; i = 3, NR_2 = aza-15-crown-5) and M- (N(SiMe_3)_2)_2 precursors. The molecular structures of these germylenes and plumbylenes, as well as those of {LO_3}GeCl, {LO_3}SnCl and of the congeneric {LO~4}Sn~(II)(N(SiMe_3)_2) where NR_2 = aza-12-crown-4, have been determined crystallographically. All complexes are monomeric, with 3-coordinate metal centres. The phenolate systematically acts as a N^O_(phenolate) bidentate ligand, with no interactions between the metal and the Oside-arm atoms in these cases (for {LO~1}~?, {LO~3}~? and {LO~4}~?) where they could potentially arise. For each family, the lone pair of electrons essentially features ns~2 character, and there is little, if any, hybridization of the valence orbitals. Heterobimetallic complexes {LO_3}M(N(SiMe_3)_2)·LiOTf, where the Li~+ cation sits inside the tethered crown-ether, were prepared by reaction of {LO~3}M(N(SiMe_3)_2) and LiOTf (M = Ge~(II), Sn~(II)). The inclusion of Li+ (featuring a close contact with the triflate anion) in the macrocycle bears no influence on the coordination sphere of the divalent tetrel element. In association with iPrOH, the amido germylenes, stannylenes and plumbylenes catalyse the controlled polymerisation of L- and racemic lactide. The activity increases linearly according to Ge~(II) ? Sn~(II) ? Pb~(II). The simple germylenes generate very sluggish catalysts, but the activity is significantly boosted if the heterobimetallic complex {LO~3}Ge(N(SiMe_3)_2)·LiOTf is used instead. On the other hand, with 10–25 equiv. of iPrOH, the plumbylenes afford highly active binary catalysts, converting 1000 or 5000 equiv. of monomer at 60 °C within 3 or 45 min, respectively, in a controlled fashion.
机译：带有氨基（醚）-酚盐配体的稳定锗（II）和铅（II）酰胺配合物{LO〜i} M（N（SiMe_3）_2）（M = Ge〜（II），Pb〜（II））可使用通式2-CH_2NR_2-4,6-〜tBu_2-C_6H_2OH（i = 1，NR_2 = N（（CH_2）_2OCH_3）_2; i = 2，NR_2 = NEt_2; i = 3，NR_2 = aza-15-crown-5）和M-（N（SiMe_3）_2）_2前体。这些种亚甲基和亚苄基以及{LO_3} GeCl，{LO_3} SnCl和同类{LO〜4} Sn〜（II）（N（SiMe_3）_2）的分子结构，其中NR_2 = aza-12 -cro-4，已在晶体学上确定。所有配合物均为单体，具有3个坐标的金属中心。酚盐系统地充当N ^ O_（酚盐）双齿配体，在这些情况下（对于{LO〜1}〜？，{LO〜3}〜？和{LO 〜4}〜？）可能会出现的地方。对于每个族，孤对电子本质上具有ns〜2特征，并且价键轨道几乎没有杂化。通过{LO〜3} M（N（SiMe_3）_2）与LiOTf的反应制备了异金属双金属配合物{LO_3} M（N（SiMe_3）_2）·LiOTf，其中Li〜+阳离子位于束缚的冠醚内部。 （M ＝ Ge〜（II），Sn〜（II））。大环中包含Li +（具有与三氟甲磺酸根阴离子紧密接触的特征）对二价蝶形元素的配位域没有影响。与iPrOH结合使用时，酰胺基三聚亚甲基，亚锡烷基和亚苄基催化L-和消旋丙交酯的受控聚合。活度根据Ge〜（II）线性增加。 Sn〜（II）？铅〜（II）简单的亚二甲基亚砜产生非常缓慢的催化剂，但是如果改用杂双金属配合物{LO〜3} Ge（N（SiMe_3）_2）·LiOTf则可以显着提高活性。另一方面，当量为10–25当量。相当于iPrOH的二甲苯提供了高活性的二元催化剂，可转化1000或5000当量。在60°C下分别在3或45分钟内以受控方式生成单体。

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