RESONANCE RAMAN STUDIES OF O-2 STRETCHING VIBRATIONS IN OXYGEN ADDUCTS OF COBALT PORPHYRINS - THE IMPORTANCE OF VIBRATIONAL COUPLING
RESONANCE RAMAN STUDIES OF O-2 STRETCHING VIBRATIONS IN OXYGEN ADDUCTS OF COBALT PORPHYRINS - THE IMPORTANCE OF VIBRATIONAL COUPLING
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DOI：
10.1021/ja00337a017
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发表时间：
1984-01-01
影响因子：
15
通讯作者：
NAKAMOTO, K
中科院分区：
文献类型：
--
作者：
BAJDOR, K;KINCAID, JR;NAKAMOTO, K
研究了振动耦合在确定钴卟啉配合物与一些轴向配体的分子O2加合物的v（O2）频率中的作用。战略同位素标记进行，以证明，多个频带和位移的v（O2）可能会出现振动耦合，并区分其他，空间或环境的影响，可能会引起这种行为的因素。强有力的证据是V（O2）和内部模式的轴向配体，发生在可比的频率之间的振动耦合。探讨了混合同位素（16 O-18 O）实验用于探测振动耦合的实用性。使用有限数量的轴向配体（吡啶和咪唑以及各种取代的类似物）和几种不同的钴卟啉（四苯基卟啉、八乙基卟啉、原卟啉IX和二甲酰基次卟啉IX二甲酯以及栅栏卟啉）的结果表明，对v（O2）的轴向和（相对较弱的）赤道电子效应与Co δ +-δ中变化分离的稳定性一致。O2 δ-公式化。此外，对v（O2）频率的相对大的影响是由结合O2与溶剂分子的相互作用引起的（例如，二氯甲烷和甲醇）。
Studies are undertaken to examine the role of vibrational coupling in determining the v(O2) frequencies of molecular O2 adducts of cobalt porphyrin complexes with a number of axial ligands. Strategic isotopic labeling was carried out in order to demonstrate that multiple bands and shifts of v(O2) may arise from vibrational coupling and to distinguish the effect from other, steric or environmental, factors that may give rise to such behavior. Strong evidence is presented for vibrational coupling between v(O2) and internal modes of axial ligands that occur at comparable frequencies. The utility of mixed-isotope (16O-18O) experiments for detecting vibrational coupling is explored. Results, using a limited number of axial ligands (pyridine and imidazole and various substituted analogues) and several different cobalt porphyrins (tetraphenylporphine, octaethylporphine, protoporphyrin IX and diformyl deuteroporphyrin IX dimethyl esters and picket-fence porphyrin), indicate that axial and (relatively weak) equatorial electronic effects on v(O2) are consistent with stabilization of change separation in the Co.delta.+-O2.delta.- formulation. Also, relatively large effects on the v(O2) frequency are brought about by interactions of bound O2 with solvent molecules (e.g., methylene chloride and methanol).