Bond formation, C-C
Wiley InterScience Backfile Collection 1832-2000
Chemistry and Pharmacology
Cycloaddition Reactions of Organometallic Complexes, XII1). - Ketenimines from Isocyanides and Diazoalkanes: A New Cobalt-Assisted C-C Bond Forming ReactionThe compounds C5H5Co(CNR)(PMe3) (1-3) react with diaryl-diazomethanes (X)(Y)CN2 to give the C,C-bound ketenimine cobalt complexes C5H5Co[η2-C,C-RN=C=CXY] (PMe3) (4-9), while the reaction of 1-3 with 9-diazofluorene leads to the formation of N,C-bound ketenimine complexes C5H5Co[η2-N,C-RN=C=C(C12H8)](PMe3) (11-13). The different bonding modes of the ketenimine ligands in 4-9 and 11-13, indicated already by the significantly different spectroscopic data, are shown by the X-ray structural analysis of 9-RCoSC (R = CHMePh; X and Y = 4-ClC6H4) and 12 (R = C6H11). On treatment of compounds 4, 6-9, 11, and 13 with an equimolar amount of iodine, free ketenimines are generated. The by-product C5H5Co(PMe3)I2 can be transformed into the starting materials 1-3 in two steps via the cations [C5H5Co(CNR)-(PMe3)I]+ as intermediates.
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