SIBAC Laboratory, Department of Physics, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk, Belgium.
Inorg Chem. 2010 Oct 4;49(19):8779-89. doi: 10.1021/ic100814j.
The synthesis, crystal structure, and electronic properties of perfluoro-isopropyl-substituted perfluorophthalocyanine bearing a copper atom in the central cavity (F(64)PcCu) are reported. While most halogenated phthalocyanines do not exhibit long-term order sufficient to form large single crystals, this is not the case for F(64)PcCu. Its crystal structure was determined by X-ray analysis and linked to the electronic properties determined by electron paramagnetic resonance (EPR). The findings are corroborated by density functional theory (DFT) computations, which agree well with the experiment. X-band continuous-wave EPR spectra of undiluted F(64)PcCu powder, indicate the existence of isolated metal centers. The electron-withdrawing effect of the perfluoroalkyl (R(f)) groups significantly enhances the complexes solubility in organic solvents like alcohols, including via their axial coordination. This coordination is confirmed by X-band (1)H HYSCORE experiments and is also seen in the solid state via the X-ray structure. Detailed X-band CW-EPR, X-band Davies and Mims ENDOR, and W-band electron spin-echo-detected EPR studies of F(64)PcCu in ethanol allow the determination of the principal g values and the hyperfine couplings of the metal, nitrogen, and fluorine nuclei. Comparison of the g and metal hyperfine values of F(64)PcCu and other PcCu complexes in different matrices reveals a dominant effect of the matrix on these EPR parameters, while variations in the ring substituents have only a secondary effect. The relatively strong axial coordination occurs despite the diminished covalency of the C-N bonds and potentially weakening Jahn-Teller effects. Surprisingly, natural abundance (13)C HYSCORE signals could be observed for a frozen ethanol solution of F(64)PcCu. The (13)C nuclei contributing to the HYSCORE spectra could be identified as the pyrrole carbons by means of DFT. Finally, (19)F ENDOR and easily observable paramagnetic NMR were found to relate well to the DFT computations, revealing negligible isotropic hyperfine (Fermi contact) contributions. The single-site isolation in solution and solid state and the relatively strong coordination of axial ligands, both attributed to the introduction of R(f) groups, are features important for materials and catalyst design.
报告了一种在中央腔中含有铜原子的全氟异丙基取代全氟酞菁（F（64）PcCu）的合成、晶体结构和电子性质。虽然大多数卤代酞菁没有表现出足够长的顺序来形成大单晶，但 F（64）PcCu 并非如此。其晶体结构通过 X 射线分析确定，并与通过电子顺磁共振（EPR）确定的电子性质相关联。这些发现得到了密度泛函理论（DFT）计算的证实，它们与实验结果非常吻合。未稀释的 F（64）PcCu 粉末的 X 波段连续波 EPR 光谱表明存在孤立的金属中心。全氟烷基（R（f））基团的吸电子效应显著提高了这些配合物在有机溶剂（如醇）中的溶解度，包括通过轴向配位。X 波段（1）H HYSCORE 实验证实了这种配位，并且在固态中也通过 X 射线结构观察到了这种配位。F（64）PcCu 在乙醇中的 X 波段 CW-EPR、X 波段 Davies 和 Mims ENDOR 以及 W 波段电子自旋回波检测 EPR 的详细研究允许确定金属、氮和氟核的主要 g 值和超精细耦合。F（64）PcCu 和其他不同基质中的 PcCu 配合物的 g 和金属超精细值的比较表明，基质对这些 EPR 参数有主要影响，而环取代基的变化只有次要影响。尽管 C-N 键的共价性降低且可能削弱 Jahn-Teller 效应，但仍然存在相对较强的轴向配位。令人惊讶的是，对于 F（64）PcCu 的冷冻乙醇溶液可以观察到天然丰度（13）C HYSCORE 信号。通过 DFT 可以将对 HYSCORE 光谱有贡献的（13）C 核鉴定为吡咯碳。最后，（19）F ENDOR 和易于观察的顺磁 NMR 与 DFT 计算结果吻合良好，表明各向同性超精细（费米接触）贡献可忽略不计。溶液和固态中单位点的隔离以及轴向配体的相对较强配位都归因于 R（f）基团的引入，这是材料和催化剂设计的重要特征。
