节点文献
桥联双芳氧基稀土配合物的合成，表征及其催化、反应行为
Synthesis, Characterization of Bridged Bis(aryloxide) Lanthanide Complexes and Their Behavior of Catalytic Reactivity
【作者】 徐小平；
【作者基本信息】 苏州大学 ， 有机化学， 2007， 博士
【摘要】 本文选取了两类桥联双芳氧基为辅助配体,分别合成了稀土金属烷氧基化合物和胺化物,研究了它们催化环酯类单体聚合的行为。文中所用桥联双芳氧基分别为:碳桥联双芳氧基CH2（4-Me-6-tBu-C6H2O）2,简写成MBMP;CH3CH（4,6-di-tBu-C6H2O）2,简写成EDBP,咪唑烷基桥联双芳氧基C3H6N2[1,4-（2-O-3,5-di-tBu-C6H2CH2）2],简写成[ONNO]。1.配合物Cp3Ln（THF）与MBMPH2按1:1的摩尔比在THF中反应1小时,然后再与1倍量的甲醇或者苄醇反应,合成了中性碳桥联双芳氧基稀土金属烷氧基配合物[（MBMP）Ln（μ-OMe）（THF）2]2 （Ln = Nd （1）, Yb （2））和[（MBMP）Ln（μ-OPh）（THF）2]2 （Ln = Nd （3）, Yb （4））,在合成产物4的过程中分离到了半水解的副产物[（MBMP）Yb（THF）2]2（μ-OPh）（μ-OH） （5）,所有产物经红外光谱,元素分析等表征。测定了配合物1和5的单晶结构,它们在固态时均具有双核结构。2.按照相同的方法,合成了以EDBP为辅助配体的稀土金属异丙氧基配合物[（EDBP）Ln（μ-OiPr）（THF）2]2 （Ln = Nd （6）, Sm（7）, Yb （8））,产物经红外光谱,元素分析等表征。测定了配合物6和7的单晶结构。结构测定显示它们在固态时均为二聚体。分离、鉴定了反应的中间体（EDBP）LnCp（THF）2 （Ln = Nd （6a）, Sm （7a）, Yb （8a））,并测定了（EDBP）YbCp（DME） （8b）的晶体结构。3.配合物Ln[N（TMS）2]3（μ-Cl）Li（THF）3和MBMPH2在THF中反应,以较好的产率合成了一类阴离子型碳桥联双芳氧基稀土金属胺化物[（MBMP）Ln{N（TMS）2}2][Li（THF）4] （Ln = Pr （9）, Nd （10）, Sm （11）, Tb （12）, Yb （13））,另外,在含有过量NaN（TMS）2的Ln[N（TMS）2]3中加入MBMPH2,反应后可以分离到与类似的阴离子型碳桥联双芳氧基稀土金属配合物[（MBMP）Ln{N（TMS）2}2][Na（DME）3] （Ln = Nd （14）, Yb （15））。产物经红外光谱,元素分析和单晶结构（11除外）等表征。4.通过{[N（TMS）2]2Nd（μ-Cl）（THF）}2与MBMPH2的质子解反应,合成了阴离子型碳桥联双芳氧基稀土金属氯化物[（MBMP）Nd（μ-Cl）（THF）2]2 （16）。这类稀土金属氯化物与硅氨基钠以1:1的摩尔比反应,可以合成中性碳桥联双芳氧基稀土金属胺化物（MBMP）LnN（TMS）2（THF）2 （Ln = Nd（17）, Yb（18））,稀土金属氯化物与硅氨钠以1:2的摩尔比反应,可以高产率地合成相应的阴离子型稀土金属胺化物14和15。产物经红外光谱,元素分析和单晶结构（18除外）等表征。5.中性碳桥联双芳氧基稀土金属胺化物17、18可以和碳化二亚胺反应,生成相应的胍基稀土金属配合物{[（μ-O）MBMP]Nd[（iPrN）2CN（TMS）2]}2 （19）和（MBMP）Yb[（iPrN）2CN（TMS）2] （20）。而阴离子型碳桥联双芳氧基稀土金属胺化物10与碳化二亚胺反应,最后却分离到了发生配体重新分配后的均配型”盐”型碳桥联双芳氧基钕配合物[（MBMP）2Nd（THF）2][Li（DME）3] （21）。中性稀土金属胺化物17、18和异氰酸苯酯的反应,分离到了意外的产物{（MBMP）Ln[μ-OC（O）NHPh]}2 （Ln = Nd （22）, Yb （23））。推测可能是配合物17和18部分水解生成相应稀土金属氢氧化物,异氰酸苯酯插入O-H键形成最终产物,并通过实验验证了这种推测。以上产物都经红外光谱、元素分析和单晶结构的表征。6.咪唑烷基桥联双酚[ONNO]H2和过量的NaH在THF中反应,以几乎定量的产率得到了桥联双芳氧基钠{[ONNO]Na2（THF）2}2,该产物经红外,核磁,和元素分析等表征,结构测定显示其在固态时为二聚体。将双芳氧基钠{[ONNO]Na2（THF）2}2、YbCl3和六甲基磷酰三胺（HMPA）按照1∶4∶4的摩尔比在THF中反应,可以以相对高的产率合成双金属咪唑烷基桥联双芳氧基镱二氯化物[ONNO][Yb2Cl2（μ-Cl）2（HMPA）2]2 （24）,配合物24和NaOiPr按1:2的摩尔比反应,可以顺利合成相应的双金属镱烷氧基配合物[ONNO][Yb2Cl2（μ-OiPr）2（HMPA）2]2 （25）,但是配合物24与大体积的NaOAr （OAr = 2,6-二叔丁基对甲苯氧基）反应,分离得到了配体重新分配的产物（ArO）2YbCl（HMPA）2 （26）和[ONNO]YbCl（HMPA）2 （27）。配合物24和位阻相对较大NaNPh2按1:2的摩尔比反应,同样分离得到了类似的单核稀土金属配合物27和（Ph2N）2YbCl（HMPA）2 （28）。配合物24和NaNPh2按1:4的摩尔比反应,成功分离到了预期的单核化合物[ONNO]YbNPh2（HMPA） （29）和（Ph2N）3Yb（HMPA）2 （30）。桥联双芳氧基钠{[ONNO]Na2（THF）2}2和YbCl3按2:1的摩尔比在THF中反应,可以高产率地合成相应的阴离子型稀土金属配合物（ONNO）2YbNa（THF）2 （31）,化合物24-31经红外光谱和元素分析等表征,并测定了化合物24-26、29-31的晶体结构。7.配合物Ln[N（TMS）2]3（μ-Cl）Li（THF）3和[ONNO]H2在THF中反应,以较好的产率合成了中性咪唑烷基桥联双芳氧基稀土金属胺化物[ONNO]LnN（TMS）2（THF） （Ln = Y （32）, La （33）, Pr （34）, Nd （35）, Sm （36）, Yb （37））,以上产物都经红外光谱和元素分析表征,配合物32、33经核磁共振表征,并测定了配合物37单晶结构。8.配合物Cp3Yb（THF）与[ONNO]H2按1:1的摩尔比在THF中反应,合成了与已知（MBMP）YbCp（THF）2类似的咪唑烷基桥联双芳氧基稀土金属茂基配合物[ONNO]YbCp （38）,产物经红外光谱、元素分析和单晶结构的表征。9.碳桥联双芳氧基稀土金属烷氧基配合物1-4、6-8都可以在相对较温和的条件下引发己内酯的可控聚合,辅助配体上的取代基以及烷氧基的改变对稀土金属催化剂的活性和可控性几乎没有影响。配合物6-8也可以在相对较温和的条件下引发环碳酸酯的聚合,显示的活性比催化己内酯聚合时的高。10.以MBMP为辅助配体的稀土金属硅氨基配合物均可以有效催化己内酯聚合。中性配合物16、17显示了和相应的稀土金属烷氧基配合物类似的活性,但它们不是可控聚合体系。阴离子型稀土金属胺化物9、10、11、13可以在室温下以较高活性催化己内酯聚合,其中以9和10为催化剂时,得到的聚合物的分子量分布比较窄,但是分子量比理论值明显偏高。当以11和13作催化剂时,得到的聚合物分子量分布较宽。11.初步探索了以咪唑烷基桥联双芳氧基为辅助配体的稀土金属氨化物催化己内酯和丙交酯聚合的活性,发现这类稀土金属胺化物显示了比阴离子型碳桥联双芳氧基稀土金属胺化物更高的催化活性。发现配合物35即使在室温下也能有效地催化丙交酯聚合。
【Abstract】 Lanthanide alkoxides and amides supported by two kinds of bridged bis（phenolato） ligands were synthesized, and their activity for the polymerization of cyclic esters were studied as well. The bridged bis（phenolato） ligands used in this thesis are as follows: carbon-bridged bis（phenolato） ligands: CH2（4-Me-6-tBu-C6H2O）2, abbreviated as MBMP; CH3CH（4,6-di-tBu-C6H2O）2, abbreviated as EDBP. Imidazolidine-bridged bis（phenolato） ligands: C3H6N2[1,4-（2-O-3,5-di-tBu-C6H2CH2）2], abbreviated as [ONNO].1. Reaction of Cp3Ln（THF） with MBMPH2 in a 1:1 molar ratio in THF at room temperature for about an hour, then with 1 equiv. of methanol or benzylic alcohol, gave the neutral bis（phenolate） lanthanide alkoxides [（MBMP）Ln（μ-OMe）（THF）2]2 （Ln = Nd （1）, Yb （2）） and [（MBMP）Ln（μ-OPh）（THF）2]2 （Ln = Nd （3）, Yb （4））. Half hydrolysis product [（MBMP）Yb（THF）2]2（μ-OPh）（μ-OH） （5） was isolated in low yield during the synthesis of complex 4. Complexes 1-4 were characterized by IR and elemental analysis. The definitive structures of 1 and 5 were confirmed by single crystal X-ray diffraction. Complexes 1 and 2 have dinuclear structure in the solid state.2. Isopropoxide lanthanide complexes supported by EDBP [（EDBP）Ln（μ-OiPr）（THF）2]2 （Ln = Nd （6）, Sm（7）, Yb （8）） were prepared in the same way as mentioned above. Complexes 6-8 were characterized by IR and elemental analysis. The definitive structures of 6 and 7 were confirmed by single crystal X-ray diffraction. Both complexes have dimeric structures in the solid state. The intermediate species of the reaction （EDBP）LnCp（THF）2 （Ln = Nd （6a）, Sm （7a）, Yb （8a）） were separated and characterized, the DME adduct （EDBP）YbCp（DME） （8b） was identified by single crystal X-ray diffraction.3. Reaction of Ln[N（TMS）2]3（μ-Cl）Li（THF）3 with 1 equiv. of MBMPH2 in THF afforded the unexpected anionic lanthanide amides [（MBMP）Ln{N（TMS）2}2][Li（THF）4] （Ln = Pr （9）, Nd （10）, Sm （11）, Tb （12）, Yb （13）） in relatively high yields. Additionally, Ln[N（TMS）2]3 containing a small amount of NaN（TMS）2 reacted with MBMPH2 to produce the analogous anionic lanthanide amides [（MBMP）Ln{N（TMS）2}2][Na（DME）3] （Ln = Nd （14）, Yb （15））. All the complexes were characterized by IR and elemental analysis. Definitive structures of all the complexes except 11 were elucidated by single crystal X-ray diffraction. 4. Reaction of {[N（TMS）2]2Nd（μ-Cl）（THF）}2 with MBMPH2 in a 1:2 molar ratio produced the carbon bridged bis（phenolate） neodymium chloride [（MBMP）Nd（μ-Cl）（THF）2]2 （16）. The neutral lanthanide amides （MBMP）LnN（TMS）2（THF）2 （Ln = Nd （17）, Yb （18）） can be prepared by the general metathesis reactions of [（MBMP）Ln（μ-Cl）（THF）2]2 with NaN（TMS）2 in a 1:1 molar ratio. The anionic lanthanide amido complexes 14 and 15 can also be synthesized by the same reaction in a 1:2 molar ratio of [（MBMP）Ln（μ-Cl）（THF）2]2 to NaN（TMS）2. Complexes 16-18 were characterized by IR, elemental analysis and single crystal X-ray diffraction （except complex 17）.5. The neutral lanthanide amides 17 and 18 reacted with carbodiimide to get the desired lanthanide guanidinate complexes {[（μ-O）MBMP]Nd[（iPrN）2CN（TMS）2]}2 （19） and （MBMP）Yb[（iPrN）2CN（TMS）2] （20）. But the ligand redistributed product [（MBMP）2Nd（THF）2][Li（DME）3] （21） can be isolated using complex 10 as the precursor. Complexes 17 and 18 reacted with PhNCO, the unexpected products {（MBMP）Ln[μ-OC（O）NHPh]}2 （Ln = Nd （22）, Yb （23）） were isolated, which were postulated to be the products from the reaction of lanthanide hydroxide formed in situ with PhNCO. In order to confirm this postulation, the lanthanide hydroxides formed by the control hydrolysis of （MBMP）LnCp（THF）2 were used to react with PhNCO, after workup, complexes 22 and 23 can be isolated in high yields. All the complexes were characterized by IR, elemental analysis and single crystal X-ray diffraction.6. Reaction of imidazolidine bridged bis（phenol）s [ONNO]H2 with excessive NaH in THF afforded the corresponding sodium salt {[ONNO]Na2（THF）2}2 in almost quantitative yield. The product was characterized by IR, 1H NMR, elemental analysis and single crystal X-ray diffraction. A dimeric structure was observed in the solid state. Reaction of {[ONNO]Na2（THF）2}2, YbCl3 and HMPA in a 1:4:4 molar ratio in THF produced a bimetallic dichloride [ONNO][Yb2Cl2（μ-Cl）2（HMPA）2]2 （24）. Complex 24 is a useful precursor for the synthesis of the corresponding lanthanide derivatives by general metathesis reactions. Reaction of 24 with NaOiPr, either in a 1:2 or in a 1:4 molar ratio, gave the corresponding lanthanide alkoxo complex [ONNO][Yb2Cl2（μ-OiPr）2（HMPA）2]2 （25）. When more bulky reagent, NaOAr （OAr = 2,6-di-tert-butyl-4-methylphenoxo） was used instead of NaOiPr, ligand redistribution reaction was occurred, （ArO）2YbCl（HMPA）2 （26） and [ONNO]YbCl（HMPA）2 （27） were isolated as final products. Reaction of complex 24 with NaNPh2 in a 1:2 molar ratio also afforded the ligand redistributed products 27 and （Ph2N）2YbCl（HMPA）2 （28）. When the molar ratio increased to 1:4, the desired products [ONNO]YbNPh2（HMPA） （29） and （Ph2N）3Yb（HMPA）2 （30） were isolated. Anhydrous YbCl3 reacted with {[ONNO]Na2（THF）2}2 in a 1:2 molar ratio, the anionic ytterbium complex （ONNO）2YbNa（THF）2 （31） could be isolated in about 85% yield. All the complexes were characterized by IR and elemental analysis, the definitive molecular structures of 24-26、29-31 were provided by single crystal X-ray diffraction.7. The silylamido complexes supported by [ONNO] ancillary ligands, [ONNO]LnN（TMS）2（THF） （Ln = Y （32）, La （33）, Pr （34）, Nd （35）, Sm （36）, Yb （37））, can be synthesized in high yields by the reaction of Ln[N（TMS）2]3（μ-Cl）Li（THF）3 with [ONNO]H2. All the complexes were characterized by IR, and elemental analysis. Complexes 32 and 33 were further confirmed by 1HNMR spectroscopy. Definitive molecular structure of complex 37 was provided by single crystal X-ray diffraction.8. Cyclopentadienyl ytterbium complex based on imidazolidine bridged bis（phenolate） ligands [ONNO]YbCp （38） can be conveniently prepared by the reaction of Cp3Yb（THF） with [ONNO]H2 in a 1:1 molar ratio in THF, which was characterized by IR, elemental analysis and single crystal X-ray diffraction.9. Carbon bridged bis（phenolate） lanthanide alkoxides 1-4, 6-8 can initiate the ring-opening polymerization ofε-caprolactone in controlled manner under mild polymerization conditions, which showed almost the same catalytic activity compared to the isopropoxide analogue. Complexes 6-8 can also initiate the ring-opening polymerization of cyclic carbonate in a higher activity.10. Silylamido lanthanide complexes based on MBMP ancillary ligand can initiate the ring-opening polymerization ofε-caprolactone. Compared with the alkoxide analogues, the neutral amido complexes demonstrated comparable catalytic activity and modest controllability, the anionic amido complexes showed higher activity, and the polymers initiated by complexes 9 and 10 have high molecule weight with narrow molecular weight distribution （MWD）. But the MWDs of polymers initiated by complexes 11 and 13 are broad.11. Preliminary studies revealed that the silylamido lanthanide complexes containing [ONNO] ligand are apparently more active initiators for the ring-opening polymerization ofε-caprolactone than the anionic amido complexes supported by carbon bridged bis（phenolate） ligands. Complex 35 can initiate effectively the polymerization of L-lactide even at room temperature.
【Key words】 bridged bis(phenolato)； lanthanide； synthesis； characterization； cyclic esters； polymerization； reaction；