Complete Rearrangement of an Organocobalt Polymer: Synthesis of a Thermally Stable Polymer Containing (Cyclobutadiene)cobalt Moieties on the Main Chain
Complete Rearrangement of an Organocobalt Polymer: Synthesis of a Thermally Stable Polymer Containing (Cyclobutadiene)cobalt Moieties on the Main Chain
复制标题
有机钴聚合物的完全重排：主链上含有（环丁二烯）钴部分的热稳定聚合物的合成
DOI：
10.1021/ma00101a050
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发表时间：
1994
期刊：
影响因子：
5.5
通讯作者：
T. Endo
中科院分区：
文献类型：
--
作者：
I. Tomita;Akinori Nishio;T. Endo
尽管有机金属聚合物在电子传导、非线性光学和液晶材料方面具有巨大的潜在用途，但只有少数报道涉及此类材料的合成。最近，我们报道了一种新的合成方法，通过二炔与（175-环戊二烯基）双（三苯膦）钴配合物的氧化偶联（即氧化闭环）获得主链中具有钴环戊二烯部分的空气稳定的有机钴聚合物（方案1）。3当使用纯化的钴单体时，这些有机钴聚合物的数均分子量（Mn）达到200 000。报道了环戊二烯钴衍生物的热重排反应，得到相应的（？）4-环丁二烯）钴的熔点以上。[4]已知所得的（环丁二烯）钴化合物是相当稳定的，因为它们与二茂铁是等电子的。5由于含（环丁二烯）钴重复单元的聚合物可以作为具有更高稳定性的新型材料，因此本文研究了有机钴聚合物的新型重排。棕色有机钴聚合物的反应（I，Mn= 35100），其通过以下物质的反应制备：（r; 5-环己基双（三苯基膦）钴与4，4 '-双（苯乙炔基）联苯3在密封管中在四氢呋喃（THF）中于110 ℃下进行1小时而不添加任何试剂，由此通过用正己烷沉淀以79%的产率获得黄色粉末状聚合物（2）（方案2）。2可溶于THF、氯仿、N，N-二甲基甲酰胺等有机溶剂，以聚苯乙烯标准样品为基础，用GPC测得其Mn为33200。从沉淀过程中的正己烷可溶级分中，检测到消除的三苯基膦。6从1和2的分子量相似性判断，不会发生副反应（如主链断裂或交联反应）。1到聚合物2的定量转化得到3在相同条件下的模型反应的支持。在这种情况下，（^-）（í？4-环-丁二烯）钴（4）通过柱色谱法以97%产率分离（方案3）。7.通过~（13）C-NMR、~（31）P-NMR、IR等手段对化合物2的结构进行了确认。8在2的NMR谱中（图1b），在4.66ppm处观察到归因于N-甲基-N-（2-甲基-N-甲基）氨基）苯基）氨基）乙基）氨基）的峰，而在1中的相应峰出现在4.76ppm处（图1a）。芳族区峰和环己基峰的积分比也支持完全转化为2。在2的13 C-NMR谱中，在83.29 ppm处检测到了α-氨基，这非常接近于4中的相应峰（83.24 ppm）。在89.70 ppm处未观察到1中起始单元的峰。3如预期的，在2的31 P-NMR谱中没有检测到峰。(a)(，ppm）c6h5 c< h，（B）c，h5
In spite of the great potential utility of organometallic polymers for electron-conductive, nonlinear optical, and liquid crystalline materials, 1· 2 there have been only a few reports dealing with the synthesis of such materials. Recently, we reported a novel synthetic methodology to obtain air-stable organocobalt polymers having cobaltacyclopentadiene moieties in the main chain by oxidative coupling (ie, oxidative ring closure) of diynes with (175-cyclopentadienyl) bis (triphenylphosphine) cobalt complex (Scheme l). 3 The number-average molecular weights (Mn) of these organocobalt polymers reached 200 000 when a purified cobalt monomer was used. A thermal rearrangement reaction of derivatives of cobaltacyclopentadiene has been reported to take place to provide the corresponding derivatives of (?; 4-cyclo-butadiene) cobalt above its meltingtemperature. 4 The resulting (cyclobutadiene) cobalt compounds are known to be quite stable, since they are isoelectronic with ferrocene. 5 Because polymerscontaining (cyclobutadiene) cobalt repeating units may serve as novel materials with higher stability, the novel rearrangement of the organocobalt polymer was examined here. The reaction of the brown-colored organocobalt polymer (I, Mn= 35100) prepared by the reaction of (r; 5-cyclo-pentadienyl) bis (triphenylphosphine) cobalt with 4, 4'-bis-(phenylethynyl) biphenyl3 was carried out at 110 C in tetrahydrofuran (THE) for 1 h in a sealed tube without any added reagents, from which a yellow powdery polymer (2) was obtained in 79% yield by precipitation with n-hexane (Scheme 2). 2 is soluble in organicsolvents such as THE, chloroform, and iV, iV-dimethylformamide, and its M „was estimated as 33 200 by GPC on the basis of standard polystyrene samples. From the n-hexane-soluble fraction in the precipitation process, the eliminated triphenylphosphine was detected. 6 Judgingfrom the similarity in the molecular weights of 1 and 2, side reactions (such as cleavage of the main chain or a cross-linking reaction) do not take place. The quantitative conversion of 1 to polymer 2 was supported by the model reaction of 3 under the same conditions. In this case,(^-cyclopentadienyl)(í? 4-cyclo-butadiene) cobalt (4) was isolated in 97% yield by column chromatography (Scheme 3). 7 Further, the structure of 2 was confirmed by-NMR, 13C-NMR, 31P-NMR, and IR analyses. 8 In the-NMR spectrum of 2 (Figure lb), a peak attributable to cyclopentadienyl moieties was observed at 4.66 ppm, while the corresponding peak in 1 appeared at 4.76 ppm (Figure la). The integral ratio of the peaks in the aromatic region and that of the cyclo-pentadienyl group also supported the complete conversion to 2. In the 13C-NMR spectrum of 2, the cyclopentadienyl group was detected at 83.29 ppm, which is very close to the corresponding peak in 4 (83.24 ppm). No peak for the starting unit in 1 was observed at 89.70 ppm. 3 As expected, no peak was detected in the 31P-NMR spectrum of 2.(a)(, ppm) c6h5 c< h,(b) c, h5