Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Sofia, Bulgaria.
Inorg Chem. 2010 Feb 15;49(4):1634-46. doi: 10.1021/ic9020299.
Solvatochromic and ionochromic effects of the iron(II)bis(1,10-phenanthroline)dicyano (Fe(phen)(2)(CN)(2)) complex were investigated by means of combined DFT/TDDFT calculations using the PBE and B3LYP functionals. Extended solvation models of Fe(phen)(2)(CN)(2) in acetonitrile and aqueous solution, as well as including interaction with Mg(2+), were constructed. The calculated vertical excitation energies reproduce well the observed solvatochromism in acetonitrile and aqueous solutions, the ionochromism in acetonitrile in the presence of Mg(2+), and the absence of ionochromic effect in aqueous solution. The vertical excitation energies and the nature of the transitions were reliably predicted after inclusion of geometry relaxation upon aqueous micro- and global solvation and solvent polarization effect in the TDDFT calculations. The two intense UV-vis absorption bands occurring for all systems studied are interpreted as transitions from a hybrid Fe(II)(d)/cyano N(p) orbital to a phenanthroline pi* orbital rather than a pure metal-to-ligand-charge transfer (MLCT). The solvatochromic and ionochromic blue band shifts of Fe(phen)(2)(CN)(2) were explained with preferential stabilization of the highest occupied Fe(II)(d)/cyano N(p) orbitals as a result of specific interactions with water solvent molecules or Mg(2+) ions in solution. Such interactions occur through the CN(-) groups in the complex, and they have a decisive role for the observed blue shifts of UV-vis absorption bands.
采用 PBE 和 B3LYP 泛函的 DFT/TDDFT 组合计算方法，研究了 Fe(phen)(2)(CN)(2) [铁(II)双(1,10-菲咯啉)二氰基]配合物的溶剂化和离子显色效应。构建了 Fe(phen)(2)(CN)(2)在乙腈和水溶液中的扩展溶剂化模型，以及包括与 Mg(2+)相互作用的模型。计算得到的垂直激发能很好地重现了在乙腈和水溶液中观察到的溶剂化变色、在乙腈中存在 Mg(2+)时的离子显色效应，以及在水溶液中不存在离子显色效应。在 TDDFT 计算中，考虑到水微环境和全局溶剂化以及溶剂极化效应下的几何弛豫，垂直激发能和跃迁性质得到了可靠的预测。对于所有研究的体系，都出现了两个强烈的紫外可见吸收带，被解释为从混合的 Fe(II)(d)/氰基 N(p)轨道到菲咯啉 pi*轨道的跃迁，而不是纯的金属-配体电荷转移（MLCT）。Fe(phen)(2)(CN)(2)的溶剂化和离子显色蓝带位移可以通过与水溶剂分子或溶液中的 Mg(2+)离子的特异性相互作用来解释，从而优先稳定最高占据的 Fe(II)(d)/氰基 N(p)轨道。这种相互作用发生在配合物的 CN(-)基团中，对观察到的紫外可见吸收带的蓝移起着决定性的作用。
