Optical absorptions and Raman scattering of metalloporphycenes reveal electronic and vibronic properties distinct from those of metalloporphyrins
Optical absorptions and Raman scattering of metalloporphycenes reveal electronic and vibronic properties distinct from those of metalloporphyrins
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金属卟啉的光学吸收和拉曼散射揭示了与金属卟啉不同的电子和振动特性
DOI：
10.1021/ja00001a020
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发表时间：
1991
影响因子：
15
通讯作者：
C. Chang
中科院分区：
文献类型：
--
作者：
W. Oertling;Weishi Wu;J. Lópéz;Younkyoo Kim;C. Chang
新合成的金属卟啉代表了一类金属卟啉的结构异构体分子。特别地，2，7，12，17-四丙基卟啉（NiPPC和CuPPC）的Ni{sup II}和Cu{sup II}配合物显示出与八乙基卟啉（OEP）的类似配合物类似的紫外-可见吸收和共振拉曼（RR）光谱。然而，仔细检查金属取代和环溴化，以及相对振子强度所造成的吸收带的位置和光谱位移，表明，与金属卟啉不同，NiPPC和CuPPC的{pi} {yields} {pi}* 状态是由单电子波函数充分定义的。因此，在金属卟啉中，产生Gouterman的Q和B金属卟啉激发态的{pi}-电子构型相互作用是弱的。相反，这些新的复合物似乎是普拉特长场分子的一个近乎完美的例子。拉曼光谱与CuPPC的主要吸收峰的共振表明几乎没有Jahn-Teller或Herzber-Teller耦合的证据。因此，金属卟啉中存在的丰富的电子振动耦合引起了著名的偏振散射，很可能不会使金属卟啉的光谱复杂化。特别是氘代衍生物的NiPPC的RR光谱的振动分析给出了一些洞察正常模式的组成。
The newly synthesized metalloporphycenes represent a class of molecules that are structural isomers of metalloporphyrins. In particular, the Ni{sup II} and Cu{sup II} complexes of 2,7,12,17-tetrapropylporphycene (NiPPC and CuPPC) display UV-visible absorption and resonance Raman (RR) spectra superficially like those of analogous complexes of octaethylporphyrin (OEP). However, close examination of absorption band positions and spectral shifts caused by metal substitution and ring bromination, as well as relative oscillator strengths, suggest that, unlike those of metalloporphyrins, the {pi} {yields} {pi}* states of NiPPC and CuPPC are adequately defined by one-electron wave functions. Thus, the {pi}-electron configuration interaction that gives rise to Gouterman's Q and B metalloporphyrin excited states is weak in metalloporphycenes. Rather, these novel complexes appear to be a near-perfect example of Platt's long-field molecules. Raman spectra in resonance with the major absorptions of CuPPC show little evidence of Jahn-Teller or Herzber-Teller coupling. Thus, the rich vibronic coupling present in metalloporphyrins giving rise to the celebrated anomalously polarized scattering most likely does not complicate the spectra of metalloporphycenes. Vibrational analyses of RR spectra of specifically deuterated derivatives of NiPPC give some insight into the normal mode compositions.