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A Domino Fusion of an Organic Ligand Depended on Metal‐Induced and Oxygen Insertion, Unraveled by Crystallography, Mass Spectrometry, and DFT Calculations
Author(s) -
Chen JinMing,
Peng Liang,
Zhou FuFang,
Liu Bin,
Hou Cheng,
Li JiaWei,
Huang Zhou,
Kurmoo Mohamedally,
Zeng MingHua
Publication year - 2021
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.202004396
Subject(s) - chemistry , ligand (biochemistry) , amide , imidazole , metal , crystallography , mass spectrometry , pyrazine , oxygen , medicinal chemistry , stereochemistry , organic chemistry , biochemistry , receptor , chromatography
Herein, the reaction of (1‐methyl‐1 H ‐benzo[ d ]imidazol‐2‐yl)methanamine ( L1 ) with Co(H 2 O) 6 Cl 2 , in CH 3 CN at 120 °C, leading to the 2,3,5,6‐tetrakis(1‐methyl‐1 H ‐benzo[ d ]imidazol‐2‐yl)pyrazine ( 3 ), isolated as a dimeric cluster {[Co II 2 ( 3 )Cl 4 ] ⋅ 2 CH 3 CN} ( 2 ), is reported. When O 2 and H 2 O are present, (1‐methyl‐1 H ‐benzo[ d ]imidazole‐2‐carbonyl)amide (H L1′ ) is first formed and crystallized as [Co III ( L1 ) 2 ( L1′ )]Cl 2 ⋅ 2 H 2 O ( 4 ) before fusion of H L1′ with L1 , giving 1‐methyl‐ N ‐(1‐methyl‐1 H ‐benzo[ d ]imidazol‐2‐carbonyl)‐1 H ‐benzo[ d ]imidazol‐2‐carboxamide (H L2′′ ) forming a 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 , for 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 with FeCl 3 ⋅ 6 H 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.