Sen Asmita, Ansari Azaj, Swain Abinash, Pandey Bhawana, Rajaraman Gopalan
Department of Chemistry, Indian Institute of Technology Bombay, Mumbai400076, India.
Inorg Chem. 2023 Sep 18;62(37):14931-14941. doi: 10.1021/acs.inorgchem.3c01632. Epub 2023 Aug 31.
Activation of C-H bonds using an earth-abundant metal catalyst is one of the top challenges of chemistry, where high-valent Mn/Fe-oxo(hydroxo) biomimic species play an important role. There are several open questions related to the comparative oxidative abilities of these species, and a unifying concept that could accommodate various factors influencing reactivity is lacking. To shed light on these open questions, here, we have used a combination of density functional theory (DFT) (B3LYP-D3/def2-TZVP) and (CASSCF/NEVPT2) calculations to study a series of high-valent metal-oxo species [MHbuea(O/OH)] (M = Mn and Fe, = II to V; Hbuea = tris[('--butylureaylato)--ethylene)]aminato towards the activation of dihydroanthracene (DHA). The H-bonding network in the ligand architecture influences the ground state-excited state gap and brings several excited states of the same spin multiplicity closer in energy, which triggers reactivity via one of those excited states, reducing the kinetic barriers for the C-H bond activation and rationalizing several puzzling reactivity trends observed in various high-valent Mn/Fe-oxo(hydroxo) species.
使用储量丰富的金属催化剂活化碳氢键是化学领域的重大挑战之一，其中高价态的锰/铁-氧（氢氧根）仿生物种起着重要作用。关于这些物种的相对氧化能力存在几个悬而未决的问题，并且缺乏一个能够综合考虑影响反应活性的各种因素的统一概念。为了阐明这些悬而未决的问题，在此，我们结合密度泛函理论（DFT）（B3LYP-D3/def2-TZVP）和（CASSCF/NEVPT2）计算方法，研究了一系列高价态金属-氧物种[MHbuea(O/OH)]（M = Mn和Fe，= II至V；Hbuea = 三[（' - 丁基脲基） - 乙烯基]氨基）对二氢蒽（DHA）的活化作用。配体结构中的氢键网络影响基态 - 激发态能隙，并使具有相同自旋多重性的几个激发态能量更接近，这通过其中一个激发态触发反应活性，降低了碳氢键活化的动力学势垒，并解释了在各种高价态锰/铁-氧（氢氧根）物种中观察到的几种令人困惑的反应活性趋势。
