694-00-8Relevant academic research and scientific papers
Coordination-Induced N-H Bond Weakening in a Molybdenum Pyrrolidine Complex: Isotopic Labeling Provides Insight into the Pathway for H2Evolution
Bezdek, Máté J.,Pelczer, István,Chirik, Paul J.
supporting information, p. 3050 - 3059 (2020/09/02)
The synthesis and characterization of a cationic molybdenum pyrrolidine complex are described that exhibits significant coordination-induced N-H bond weakening. The N-H bond dissociation free energy (BDFE) of the coordinated pyrrolidine in [(PhTpy)(PPh2Me)2Mo(NH(pyrr))][BArF24] ([1-NH(pyrr)]+PhTpy = 4′-Ph-2,2′,6′,2″-terpyridine, NH(pyrr) = pyrrolidine, ArF24 = [C6H3-3,5-(CF3)2]4) was determined to be between 41 and 51 kcal mol-1 by thermochemical analysis and supported by a density functional theory (DFT) computed value of 48 kcal mol-1. The complex [1-NH(pyrr)]+ underwent proton-coupled electron transfer (PCET) to 2,4,6-tri-tert-butylphenoxyl radical, as well as spontaneous H2 evolution upon gentle heating to furnish the corresponding molybdenum pyrrolidide complex [(PhTpy)(PPh2Me)2Mo(N(pyrr))][BArF24] ([1-N(pyrr)]+). Thermolysis of the deuterated isotopologue [1-ND(pyrr)]+ still produced H2 with concomitant incorporation of the isotopic label into the pyrrolidide ligand in the product [(1-N(pyrr-dn)]+ (n = 0-2), consistent with an H2 evolution pathway involving intramolecular H-H bond formation followed by an intermolecular product-forming PCET step. These observations provide the context for understanding H2 evolution in the nonclassical ammine complex [(PhTpy)(PPh2Me)2Mo(NH3)][BArF24] ([1-NH3]+) and are supported by DFT-computed reaction thermochemistry. Overall, these studies offer rare insight into the H2 formation pathway in nonclassical amine complexes with N-H BDFEs below the thermodynamic threshold for H2 evolution and inform the development of well-defined, thermodynamically potent PCET reagents.
Unexpected resistance to base-catalyzed hydrolysis of nitrogen pyramidal amides based on the 7-azabicyclic[2.2.1]heptane scaffold
De Velasco, Diego Antonio Ocampo Gutiérrez,Su, Aoze,Zhai, Luhan,Kinoshita, Satowa,Otani, Yuko,Ohwada, Tomohiko
, (2018/09/26)
Non-planar amides are usually transitional structures, that are involved in amide bond rotation and inversion of the nitrogen atom, but some ground-minimum non-planar amides have been reported. Non-planar amides are generally sensitive to water or other n
A simple method for α-position deuterated carbonyl compounds with pyrrolidine as catalyst
Zhan, Miao,Zhang, Tao,Huang, Haoxi,Xie, Yongmei,Chen, Yuanwei
, p. 533 - 539 (2014/08/05)
A simple, cost-effective method for deuteration of carbonyl compounds employing pyrrolidine as catalyst and D2O as deuterium source was described. High degree of deuterium incorporation (up to 99%) and extensive functional group tolerance were achieved. It is the first time that secondary amines are used as catalysts for H/D exchange of carbonyl compounds, which also allow the deuteration of complex pharmaceutically interesting substrates. A possible catalytic mechanism, based on the hydrolysis of 1-pyrrolidino-1- cyclohexene, for this pyrrolidine-catalyzed H/D exchange reaction has been proposed. Pyrrolidine has been shown to be an efficient catalyst for deuteration of carbonyl compounds. The method also allowed the deuteration of complex pharmaceutically interesting substrates. Preliminary experiment showed that the enamine and/or iminium activation modes may be involved. Copyright
