期刊
JACS AU
卷 1, 期 5, 页码 623-645出版社
AMER CHEMICAL SOC
DOI: 10.1021/jacsau.1c00106
关键词
Carbonyl complexes; transition metals; bonding analysis; Dewar-Chatt-Duncanson model; EDA-NOCV calculations
资金
- Deutsche Forschungsgemeinschaft
- Spanish Ministerio de Ciencia e Innovacion (MICIIN) [PID2019-106184GB-I00, RED2018-102387T]
DFT calculations and various analysis approaches were used to investigate the bonding situations and trends between metals and carbonyl ligands, emphasizing the increase in polarity of M-CO bonds with decreasing electronegativity of the metals.
DFT calculations have been carried out for coordinatively saturated neutral and charged carbonyl complexes [M(CO)(n)](q) where M is a metal atom of groups 2-10. The model compounds M(CO)(2) (M = Ca, Sr, Ba) and the experimentally observed [Ba(CO)](+) were also studied. The bonding situation has been analyzed with a variety of charge and energy partitioning approaches. It is shown that the Dewar-Chatt-Duncanson model in terms of M <- CO sigma-donation and M -> CO pi-backdonation is a valid approach to explain the M-CO bonds and the trend of the CO stretching frequencies. The carbonyl ligands of the neutral complexes carry a negative charge, and the polarity of the M-CO bonds increases for the less electronegative metals, which is particularly strong for the group 4 and group 2 atoms. The NBO method delivers an unrealistic charge distribution in the carbonyl complexes, while the AIM approach gives physically reasonable partial charges that are consistent with the EDA-NOCV calculations and with the trend of the C-O stretching frequencies. The AdNDP method provides delocalized MOs which are very useful models for the carbonyl complexes. Deep insight into the nature of the metal-CO bonds and quantitative information about the strength of the [M] <- (CO)(8) sigma-donation and [M(d)] -> (CO)(8) pi-backdonation visualized by the deformation densities are provided by the EDA-NOCV method. The large polarity of the M-CO pi orbitals toward the CO end in the alkaline earth octacarbonyls M(CO)(8) (M = Ca, Sr, Ba) leads to small values for the delocalization indices delta(M-C) and delta(M center dot center dot center dot O) and significant overlap between adjacent CO groups, but the origin of the charge migration and the associated red-shift of the C-O stretching frequencies is the [M(d)] -> (CO)(8) pi-backdonation. The heavier alkaline earth metals calcium, strontium and barium use their s/d valence orbitals for covalent bonding. They are therefore to be assigned to the transition metals.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据