| Summary: | 碩士 === 國立成功大學 === 化學系碩博士班 === 92 === The NBO results indicate that besides the conventional dπ(M)→2π(CO) donor-acceptor interaction, in the uniform order 3d< 4d < 5d for each group under studies, there are two other significant D-A interaction. Firstly, the 5σ(CO)→2π(CO) indication which reveals the trend 3d>5d~4d. The secondtype interaction, σ(M-C) →2π(CO), which also exhibits the same trend. This trend is partically evident for the 6B group. Therefore, the experimental results observed for the 6B group can be understood as the latter two interactions tend to compatible with the dπ(M)→2π(CO) interaction. The detailed discussion of σ(M-C) →2π(CO) is also presented.
Analyzed of charge transfer and values of E(2) for the dπ(M)→Ryd(X) interaction in series 2 complexes reveals that the trend of this interaction, Br-> Cl-> F-. This reverse order of the halides’ donor capability, therefore, will counterbalance the expected ligand nature of the three ligands.
The unusual directionality found for M(CO)5X- can also be explained by the NBO results, In which the dπ-pπ interaction is orientational favored for the trans-CO. It is therefore not surprised that one would find the ligand effect is much more pronounce for the trans-CO than the radial ones.
Finally, NBO result indicates that the effect through space interaction between CO and benzene on phoshine in W(CO)5PR3 is limited. And, the result and NMR experiments have the same tendency.
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