本篇論文透過計算化學方法密度泛函數理論(density functional theory, DFT) 搭配CPCM溶劑模型(Conductor-like polarizable continuum model)來探討非氧化釩硫醇鹽錯合物 [V(PS3”)2]- (1) (PS3” = [P(C6H3-3-Me3Si-2-S)3]3-)進行一系列極性小分子活化過程的反應性。
起初，我們利用錯合物 1上的S原子來進行H2O O-H activation，卻無法取得反應之過渡態，而後我們經由剖析實驗上所獲得之產物，進一步推斷錯合物 1在進行反應前可能會透過斷裂單一V-S鍵，使其本身能夠帶有更強的自由基性質來提升錯合物之反應性，進而得以進行H2O O-H activation。
根據計算結果，與預期的推論一致，我們發現錯合物 1會先從原先8配位結構轉變為7配位錯合物 1-O，且於過程中，整體化合物之自旋電子密度會集中於錯合物 1-O之S6原子上，使得錯合物 1-O具有更強的自由基特性與反應性來進行接續的反應。而後經由分析反應過程之過渡態，我們得知錯合物 1能夠活化H2O O-H鍵之原因。促使錯合物 1得以斷裂H2O O-H鍵的原因在於反應過程中錯合物 1內之S3原子會與H2O的O-H產生相互作用力，進而能夠穩定過渡態分子，最終以懸臂上之S6自由基來抽取H原子，然而，錯合物 1卻無法活化PhCH3 C-H鍵(sp3)，主要是因為缺乏PhCH3與錯合物 1內之S3原子的相互作用力，進而導致整體反應需要更高的活化能才得以達成。
經由一系列DFT計算結果的分析與討論，我們最終成功推論出錯合物 1在活化H2O O-H鍵可能的反應機構，且此類藉由complex ligand-ligand cooperation的方式來進行O-H activation，是一套全新且獨一無二的系統，也因此，我們更進一步探討此系統對於其他帶有極強鍵極性小分子(如NH3)進行活化的反應性以及取代基效應對於錯合物 1活化各分子之影響。
最終，我們發現當我們將原先錯合物 1上之取代基SiMe3分別替換為SiH3、CH3、H、Ph、3-H-5-CH3後，能夠有效降低整體錯合物分子之立體障礙，穩定反應過程中之過渡態結構與能量，使其在進行C-H activation、O-H activation、N-H activation及C-O activation上相對容易，因而能夠適時降低反應所需的活化能與反應熱。而除了錯合物本身立體障礙的影響外，取代基誘導效應以及錯合物 1於S3原子上之電子自旋密度亦是影響著整體反應活性的關鍵因素。

Quantum Mechanics combined with the CPCM solvation model was used to investigate the reactivity of newly synthesized vanadium-thiolate complexes (1) toward some small molecules such as H2O, toluene, CH3OH, and NH3. Our calculations showed that eight-coordinated 1 must dissociate one of its coordinated thiyl groups to become reactive. The seven-coordinated vanadium complex (1-O) is then able to cleave O-H bonds of H2O with a kinetical barrier (Ea) of only 23.3 kcal/mol. In contrast, the Ea of the cleavage of methylene C-H bonds of toluene by 1 is as higher as 28.9 kcal/mol. The calculated results are qualitatively consistent with the experimental observation, showing 1 is able to activate H2O but not toluene. Analyzing the transition state structures, we found this is due to an additional interaction between OH of the activating H2O and one of the coordinated S atoms, which helps to stabilize the transition state, leading to its lower Ea. This interaction is missing for toluene C-H activation, resulting in its higher Ea. Importantly, compared to known mechanisms, we found that activation of H2O by 1 is proceeded through a unique ligand-ligand cooperation fashion, in which hydrogen of H2O is transferred to the dissociated S and the remaining OH group is bound to one of the coordinated S, whereas vanadium is not involved directly. This represents a novel pathway for H2O activation. To gain more insights into this pathway, the effect of substituent on the thiolate ligands on the potential energy surfaces was investigated.

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