Broclawik Ewa, Stępniewski Adam, Radoń Mariusz
Jerzy Haber Institute of Catalysis PAS, ul. Niezapominajek 8, 30-239 Krakow, Poland.
Jerzy Haber Institute of Catalysis PAS, ul. Niezapominajek 8, 30-239 Krakow, Poland.
J Inorg Biochem. 2014 Jul;136:147-53. doi: 10.1016/j.jinorgbio.2014.01.010. Epub 2014 Jan 22.
The nature of electron density transfer upon bond formation between NO ligand and Fe(II) center is analyzed on the basis of DFT calculation for two {Fe-NO}(7) complexes with entirely diverse geometric and electronic structures: Fe(II)P(NH3)NO (with bent Fe-N-O unit) and Fe(II)(H2O)5(NO) (with linear Fe-N-O structure). Proper identification of an electronic status of the fragments, "prepared" to make a bond, was found necessary to get meaningful resolution of charge and spin transfer processes from a spin-resolved analysis of natural orbitals for chemical valence. The Fe(II)P(NH3)NO adduct (built of NO(0) (S=1/2) and Fe(II)P(NH3) (S=0) fragments) showed a strong π*-backdonation competing with spin transfer via a σ-donation, yielding significant red-shift of the NO stretching frequency. Fe(II)(H2O)5(NO) (built of NO(0) (S=1/2) antiferromagnetically coupled to Fe(II)(H2O)5 (S=2) fragment) gave no noticeable charge or spin transfer between fragments; a slight blue-shift of the NO stretching frequency could be related to a residual π-donation due to weak π-bonding.
基于密度泛函理论（DFT）计算，对具有完全不同几何和电子结构的两种{Fe-NO}(7)配合物：Fe(II)P(NH3)NO（具有弯曲的Fe-N-O单元）和Fe(II)(H2O)5(NO)（具有线性Fe-N-O结构），分析了NO配体与Fe(II)中心之间形成键时电子密度转移的性质。发现正确识别“准备”形成键的片段的电子状态，对于从化学价自然轨道的自旋分辨分析中获得电荷和自旋转移过程的有意义分辨率是必要的。Fe(II)P(NH3)NO加合物（由NO(0)（S = 1/2）和Fe(II)P(NH3)（S = 0）片段组成）显示出强烈的π* - 反馈，与通过σ - 给予的自旋转移竞争，导致NO伸缩频率显著红移。Fe(II)(H2O)5(NO)（由与Fe(II)(H2O)5（S = 2）片段反铁磁耦合的NO(0)（S = 1/2）组成）在片段之间没有明显的电荷或自旋转移；NO伸缩频率的轻微蓝移可能与由于弱π键导致的残余π - 给予有关。
