Jin‐Ming Chen, Liang Peng, Fufang Zhou
Nov 24, 2020
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Influential Citations
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Journal
Chemistry
Abstract
Here, we report the reaction, CH 3 CN at 120 °C, of (1-methyl-1H-benzo[d]imidazol-2-yl)methanamine ( L1 ) with Co(H 2 O) 6 Cl 2 leading to the 2,3,5,6-tetrakis(1-methyl-1H-benzo[d]imidazol-2-yl)pyrazine ( 3 ), isolated as a dimeric cluster {[Co II 2 ( 3 )Cl 4 ]∙2CH 3 CN} ( 2 ). When O 2 and H 2 O are present, (1-methyl-1H-benzo[d]imidazole-2-carbonyl)amide ( HL1' ) is first formed and crystallized as [Co III ( L1 ) 2 ( L1' )]Cl 2 ∙2H 2 O ( 4 ) before fusion of H L1' with L1 giving 1-methyl-N-(1-methyl-1H-benzo[d]imidazol-2-carbonyl)-1H-benzo[d]imidazol-2-carboxamide ( HL2'' ) forming one-dimensional (1D) chain of [Co II 3 ( L2'' ) 2 Cl 4 ] n ( 5 ). The combination of crystallography and mass spectrometry (ESI-MS) of isolated crystals and the solutions taken from the reaction as a function time reveal seven intermediate steps leading to 2 , but six steps for 5 which a different sequence takes place. Control and isotope labeling experiments confirm the two carbonyl oxygen atoms in 5 originate from both air and water. The dependence on the metals, compared to FeCl 3 ·6H 2 O leading to a stable triheteroarylmethyl radical, is quite astounding, which could be attributed to the different oxidation states of the metals and coordination modes confirmed by DFT calculations. This metal and valence dependent process is a very useful way for selectively obtaining these large molecules which are unachievable by common organic synthesis.