Dipolar Second-Order Nonlinear Optical Chromophores Containing Ferrocene, Octamethylferrocene, and Ruthenocene Donors and Strong π-Acceptors: Crystal Structures and Comparison of π-Donor Strengths.
Dipolar Second-Order Nonlinear Optical Chromophores Containing Ferrocene, Octamethylferrocene, and Ruthenocene Donors and Strong π-Acceptors: Crystal Structures and Comparison of π-Donor Strengths.
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含有二茂铁、八甲基二茂铁和钌茂供体和强α-受体的偶极二阶非线性光学发色团：晶体结构和α-供体强度比较。
DOI：
10.1021/om800986s
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发表时间：
2009
期刊：
影响因子：
2.8
通讯作者：
Barlow,Stephen
中科院分区：
文献类型：
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作者：
Kinnibrugh,TiffanyL;Salman,Seyhan;Getmanenko,YuliaA;Coropceanu,Veaceslav;Porter3rd,WilliamW;Timofeeva,TatianaV;Matzger,AdamJ;Brédas,Jean-Luc;Marder,SethR;Barlow,Stephen
已经确定了六种双极性多烯发色团的晶体结构，它们分别为茂金属基二茂铁基（Fc）、八甲基二茂铁基（Fc”）或鲁thenocenyl （Rc）供体和基于1,3-二乙基-2-硫代巴比妥酸或3-二氰甲基-2,3-二氢苯并噻吩-1,1-二氧化基的强杂环受体。在每种情况下，发现晶体都属于中心对称空间群。例如，聚合物诱导的异核反应揭示了另外两种形式的存在，它们在二次谐波中不活跃，这表明它们也是中心对称的。与简单的多烯相比，多烯桥的双键和单键之间的键长变化减小，表明电荷分离共振结构对多烯桥的键长变化有重要贡献，尽管金属二烯并没有明显地向[(η - 6-fulvene)（η - 5-环戊二烯基）金属（II）]+极端扭曲。DFT几何形状与晶体学上确定的几何形状非常一致；虽然三种金属二烯基的π给体强度的差异不足以导致晶体键长变化的可检测到的差异，但DFT几何形状和原子部分电荷的DFT计算表明，π给体强度在Fc " > Fc > Rc的顺序上减小。核磁共振、红外和电化学证据也表明，八甲基二茂铁是较强的π给体，其π给体强度与ap-（二烷基胺）苯基相似，而二茂铁和钌烯基在这类发色团中表现出非常相似的π给体强度。
Crystal structures have been determined for six dipolar polyene chromophores with metallocenylferrocenyl (Fc), octamethylferrocenyl (Fc′′), or ruthenocenyl (Rc)donors and strong heterocyclic acceptors based on 1,3-diethyl-2-thiobarbituric acid or 3-dicyanomethylidene-2,3-dihydrobenzothiophene-1,1-dioxide. In each case, crystals were found to belong to centrosymmetric space groups. For one example, polymer-induced heteronucleation revealed the existence of two additional forms, which were inactive in second-harmonic generation, suggesting that they were also centrosymmetric. The bond-length alternations between the formally double and single bonds of the polyene bridges are reduced compared to simple polyenes, indicating significant contribution from charge-separated resonance structures, although the metallocenes are not significantly distorted toward the [(η6-fulvene)(η5-cyclopentadienyl)metal(II)]+extreme. DFT geometries are in excellent agreement with those determined crystallographically; while the π-donor strengths of the three metallocenyl groups are insufficiently different to result in detectable differences in the crystallographic bond-length alternations, the DFT geometries, as well as DFT calculations of partial charges for atoms, suggest that π-donor strength decreases in the order Fc′′ ≫ Fc > Rc. NMR, IR, and electrochemical evidence also suggests that octamethylferrocenyl is the stronger π-donor, exhibiting similar π-donor strength to ap-(dialkylamino)phenyl group, while ferrocenyl and ruthenocenyl show very similar π-donor strengths to one another in chromophores of this type.