节点文献
稀土双负离子胍基配合物的合成及反应性研究
【作者】 郑鹏志；
【导师】 周锡庚；
【作者基本信息】 复旦大学 ， 有机化学， 2010， 博士
【摘要】 胍配体有着丰富的配位化学,在近20年的发展中,人们对胍配合物的研究从最开始的合成各种配合物到最近对它们在催化和材料科学方面应用的研究,可谓是方兴未艾。值得关注的是,尽管预期双负离子胍基配合物将比单负离子和中性胍配合物具有更丰富的配位模式和反应化学,但对双负离子胍基配合物的研究目前却还很少报道,且主要集中在过渡和主族金属。究其原因,可能是缺乏合成这类配合物的有效方法。为了深入了解双负离子胍基配合物的结构特点和反应性质,本论文重点研究了稀土双负离子胍基配合物的合成方法、配位模式和反应性质。共合成和表征了46个新的稀土金属有机化合物,并测定了其中39个化合物的晶体结构。取得了下述主要成果：1.发展了通过稀土单负离子胍基配合物脱质子制备茂基稀土双负离子胍基配合物的方法。首先,利用Cp3Ln与中性胍(iPrNH)2C=NPh的反应,合成了单负离子胍基配合物中间体Cp2Ln[iPrNC(NPh)NHiPr] [Ln = Yb (2-1), Y (2-2), Er(2-3)],然后,利用丁基锂进一步脱质子,得到了对应的杂双核双负离子胍基二茂稀土配合物Cp2Ln[(iPrN)2CNPh]Li(THF)3 [Ln = Yb (2-10), Y (2-11), Er (2-12)];有趣的是,同样条件下,Cp3Ln与(CyNH)2CNPh反应,只能分离得到二胍基一茂稀土配合物中间体CpLn[CyNC(NPh)NHCy]2(THF)n [Ln = Yb (2-5), Er (2-6), Gd(2-7)], 2-5与nBuLi反应则形成含单负／双负离子混合胍配体配位的一茂稀土配合物CpYb[CyNC(NPh)NCy][(CyN)2CNPhLi(THF)3](2-18),因此,氮原子上含环己基取代基的二茂稀土双负离子胍基配合物Cp2Ln[(CyN)2CNPh]Li(THF)3 [Ln = Yb (2-13), Y (2-14), Er (2-15), Dy (2-16)]需要通过Cp3Ln与等摩尔的(CyNH)2CNPh和nBuLi的“一锅”反应合成；而Cp2Er[(CyN)3C]Li(THF)2(2-17)也可以通过Cp2LnCl与[CyNC(NPh)NHCy]Li和nBuLi的连续反应制备；此外,通过Cp3Ln与C6H4[NC(NHCy)2-1,4]2和C6H4[NC(NHiPr)2-1,4]2的反应,我们还合成了苯基桥联的双胍基稀土配合物C6H4[(NC(NCy)NHCy)YCp2(THF)]2-1,4(2-8)和C6H4[(NC(NiPr)NHiPr)YbCp2]2-1,4 (2-9),但是,试图用丁基锂脱化合物2-8和2-9配体上的质子,合成对应的桥联双负离子胍基配合物还未成功。有意义的是,在探索合成茂基稀土双负离子胍基配合物的新途径中,还意外地得到了非预期的硅酮插入产物{[Cp2Y(Me2Si(O)NPh)][Li(THF)4]}2 (2-19)和碳化二亚胺双插入产物CpYb[nBuC(NCy)2][CyN{C(NCy)2}2Li(THF)](2-20)。2.开拓性研究了茂基稀土双负离子胍基配合物的反应性质,发现Cp2Ln[(RN)2CNPh]Li(THF)3类化合物能与氯硅烷反应,生成四取代的胍基稀土配合物Cp2Ln[(RN)2C(NPhSiMe2R’)] [R = Cy, R’= Me: Ln= Yb (3-1), Ln= Y (3-2),Ln = Er(3-3); R = Cy, R’= tBu: Ln = Yb(3-4), Ln= Er(3-5); R =iPr,R’ = tBu: Ln = Yb(3-6), Ln = Er(3-7)];进一步,Cp2Ln[(CyN)2CNPh]Li(THF)3类化合物还能与Me2SiCl2反应,形成首例四元硅氮杂环有机物Me2Si(CyN)2C=NPh(3-8)。同时,这些与稀土配位的双负离子胍配体还能夺质子,转变为单负离子的胍配体。这些研究结果显示,双负离子胍配体上的负电荷是离域于整个CN3结构单元上,随着反应体系的不同,双负离子胍配体上反应活性位点具有可变性。同时也提供了一种合成多取代胍基稀土配合物的方法。3.率先研究了茂基稀土双负离子胍基配合物与芳酰氯的反应。与氯硅烷反应不同,Cp2Ln[(RN)2CNPh]Li(THF)3与ArCOCl反应生成酰胺化/碳化二亚胺消除产物,这表明反应生成的酰基化胍配体不稳定,容易进一步发生碳化二亚胺消除反应。有意义的是,我们还发现酰基化位点是可控的,当R为异丙基和环己基时,酰基化反应都是发生在与稀土螯合配位的氮原子上,得到的产物是[Cp2LnOC(Ar)NR)]2 [R= iPr, Ar = Ph: Ln = Yb (4-1), Ln = Y (4-2), Ln = Er (4-3), Ln = Dy (4-4), Ln = Gd (4-5); R = iPr, Ar = 4-ClPh: Ln= Yb (4-6), Ln = Y (4-7), Ln = Er (4-8); R = Cy, Ar = Ph: Ln= Yb (4-9), Ln = Y (4-10), Ln = Er (4-11), Ln = Dy(4-12)]；而当R为立体位阻更大的2,6-二异丙基苯基时,酰化反应则发生在与锂离子配位的氮原子上,产物为[Cp2YbOC(Ph)NPh)]2 (4-13)。类似的胍配体转化反应在文献中还未见报道,这不仅进一步阐明了双负离子胍基配体反应位点的多变性和潜在的丰富反应化学,而且还为稀土酰胺基配合物和不对称碳化二亚胺的合成提供了新方法。4.通过LnCl3与原位生成的双负离子胍基锂盐或单负/双负离子混合胍基锂盐反应,合成了一系列不含茂基辅助配体的稀土双负离子胍基配合物{Ln[(iPrN)2CNPhLi(THF)n][(iPrN)2CNPh]}2 [n = 2: Ln = Yb (5-1), Er (5-2); n = 3: Ln = Er (5-3)]和{Y[(CyN)3CLi(THF)2][(CyN)3C]}2(5-4),以及单负离子胍基和双负离子胍基混合配位的非茂稀土配合物{Ln[iPrNC(NPh)iPrNH][(iPrN)2CNPh]}2 [Ln = Yb(5-5),Er(5-6)]。惊奇的是,与含茂基配体的稀土双负离子胍基配合物不同,5-3和5-4与氯硅烷不发生反应。
【Abstract】 During the past 20 years, guanidinate anions have emerged as an extremely versatile class of ligands. From pure preparative chemistry to applications in various fields, the potential of metal guanidinate complexes is far from being exhausted. However, a number of white spots still exist. There are considerably fewer examples of complexes containing a guanidinate dianionic ligand than the monoanionic or neutral ligands, and the limited several examples were mailly concerned with main group and transition metals, which may astrict the general acquaintance with the coordination chemistry of guanidine and their potential application. This is surprising, given the fact that guanidinate dianions could function as a diamido ligand and may exhibitπdelocalization (Y conjugation) of the lone pairs on the sp2 hybridized nitrogen centers, with may endow it with more rich and novel coordination models and reaction properties. The lack of proper synthetic methodology may be the main hindrance. The above reasons inspired us to the research of the synthesis, reaction properties and the coordination models of lanthanide guanidinate dianionic complexes. 47 new complexes were synthesized,40 of them were characterized by X-Ray single crystal diffraction analysis. The main aspects of this thesis are as follows.1. We have developed a convenient and applicable methodology for synthesis of cyclopentadienyl-contained lanthanide guanidinate dianionic complexes by deprotonation of monoanionic guanidinate ligands. Firstly, monoanionic guanidinate intermediate complexes [Ln= Yb (2-1), Y (2-2), Er (2-3)] were synthesized by deprotonation of (iPrNH)2C=NPh with Cp3Ln, then by further deprotonation of Cp2Ln[’PrNC(NPh)NH’Pr] with "BuLi afford guanidinate dianionic organolanthanide complexes Cp2Ln[(’PrN)2CNPh]Li(THF)3 [Ln= Yb (2-10), Y (2-11), Er (2-12)]; Differently, under the same conditions, monoanionic guanidinate intermediate complexes CpLn[CyNC(NPh)NHCy]2(THF)n [Ln= Yb (2-5), Er (2-6), Gd (2-7)] were merely obtained by reaction of Cp3Ln with (CyNH)2CNPh, reaction of 2-5 with "BuLi give a complexe with mixed mono-/dianionic guanidinate ligands CpYb[CyNC(NPh)NCy][(CyN)2CNPhLi(THF)3] (2-18). Thus, guanidinate dianionic organolanthanide complexes Cp2Ln[(CyN)2CNPh]Li(THF)3 [Ln= Yb (2-13), Y (2-14), Er (2-15), Dy (2-16)] should be prepared by "one pot" reaction of equivalent mol of Cp3Ln with (CyNH)2CNPh and "BuLi; Similarly, Cp2Er[(CyN)3C]Li(THF)2 (2-17) can be obtained by continuous reaction of Cp2LnCl with [CyNC(NPh)NHCy]Li and nBuLi; Besides, reaction of Cp3Ln with C6H4[NC(NHCy)2-1,4]2 or C6H4[NC(NH’Pr)2-1,4]2 gave phenyl bridged diguanidinate complexes C6H4[(NC(NCy)NHCy)YCp2(THF)]2-1,4 (2-8) and C6H4[(NC(N’Pr)NH’Pr)YbCp2]2-1,4 (2-9), however, endeavor to synthesize the corresponding bridged dianionic guanidinate complexes by further deprotonation of (2-8) or (2-9) with "BuLi were unsuccessful. Significantly, two unanticipated products: a silicon insertion complex{[Cp2Y(Me2Si(O)NPh)][Li(THF)4]}2 (2-19) and a carbodiimide diinsertion complex Cp[nBuC(NCy)2]Yb{CyN[C(NCy)2]2Li(THF)} (2-20) were obtained during the exploration of other synthetic method for cyclopentadienyl-contained lanthanide guanidinate dianionic complexes.2. We initiatively studied the reaction properties of cyclopentadienyl-contained lanthanide guanidinate dianionic complexes. We found that, Cp2Ln[(RN)2CNPh]Li(THF)3 could react with chlorosilanes with the formation of tetra-substituted guanidinate monoanionic lanthanide complexes Cp2Ln[(RN)2C(NPhSiMe2R’)] [R= Cy, R’= Me:Ln= Yb (3-1), Ln=Y (3-2), Ln= Er (3-3); R= Cy, R’=tBu:Ln= Yb (3-4), Ln= Er (3-5); R=iPr, R’=tBu:Ln= Yb (3-6), Ln= Er (3-7)]; Furthermore, Cp2Ln[(CyN)2CNPh]Li(THF)3 could react with Me2SiCl2 to afford the unprecedented four-numbered silicon-contained organic compound Me2Si(CyN)2C=NPh (3-8). Simultaneously, the coordinated guanidinate dianionic ligands can convert to guanidinate monoanionic ligands with acquirement of proton. These features are consistent with negative charges of the guanidinate dianion ligand delocalized on the three N atoms and thus demonstrate that the active site of the ligand is tunable.3. Initiatively studied the reaction of cyclopentadienyl-contained lanthanide guanidinate dianionic complexes towards acyl chloride. Different from the reactions of Cp2Ln[(RN)2CNPh]Li(THF)3 with chlorosilanes, the dianionic guanidinate ligand underwent a tandem acylation/elimination process to afford acylamino complexes, which indicated that, the generated acylation guanidinates were unstable, it inclined to eliminate dicarbodiimide moiety in succession. What is more significant, we found that the acylation site of the ligand is tunable, when R=iPr or Cy, acylation site is on the chelated N atom with lanthanide metal atom, to produce [Cp2LnOC(Ar)NR)]2 [R-iPr, Ar=Ph:Ln= Yb (4-1), Ln= Y (4-2), Ln= Er (4-3), Ln= Dy (4-4), Ln= Gd (4-5); R=iPr, Ar= 4-ClPh:Ln= Yb (4-6), Ln= Y (4-7), Ln= Er (4-8); R=Cy, Ar= Ph:Ln= Yb (4-9), Ln= Y (4-10), Ln= Er (4-11), Ln= Dy (4-12)]. However, when R = 2,6-iPr2C6H3, acylation site is on the N atom which coordinated to Li atom, to afford [Cp2YbOC(Ph)NPh)]2 (4-13), the analogously covertion of guanidinate ligands have never been reported before. Those results not only further illuminated the diversity active sites of the guanidinate dianionic ligands and their potential abundance reaction properties but also afford a new way for the preparation of asymmetry dicarbodiimides.4. By reaction of LnCl3 with in-situ generated dianionic guanidinate or mixed di-/monoanionic guanidinate ligands, a series of cyclopentadienyl-free lanthanide guanidinate dianionic complexes{Ln[(iPrN)2CNPhLi(THF)n][(iPrN)2CNPh]}2 [n= 2: Ln= Yb (5-1), Er (5-2); n= 3:Ln= Er (5-3)],{Y[(CyN)3CLi(THF)2][(CyN)3C]}2 (5-4) and{Ln[iPrNC(NPh)iPrNH][(iPrN)2CNPh]}2 [Ln= Yb (5-5), Er (5-6)] were obtained. To our surprise, different from the reactions of cyclopentadienyl-contained lanthanide guanidinate dianionic complexes,5-3 and 5-4 were inert toward chlorosilanes.