Intramolecular proton-hydride activation using the example of cobalt bis(dicarbollide) derivative [8-Et(HO)C=HN-3,3′-Co(1,2-C2B9H10 )(1′,2′-C2B9H11)]статья
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Аннотация:Heating the propionamide derivative of cobalt bis(dicarbollide) [8-Et(HO)C=HN-3,3’-Co(1,2-C2B9H10)(1’,2’-C2B9H11)] at temperatures above 200 °C leads to the activation of the BH and OH (or NH) bonds through the corresponding dihydrogen bonds with the formation of 8,8’-N,O-bridged derivative [8,8’-μ-(NH=C(Et)O-N,O)-3,3’-Co(1,2-C2B9H10)2] and 8,9(12)-fused oxazole [8,9(12)-(NH=C(Et)O-N,O)-3,3’-Co(1,2-C2B9H9)(1’,2’-C2B9H11)], along with minor amount of 8,8’-N-bridged derivative [8,8’-μ-Et(HO)C=N-3,3’-Co(1,2-C2B9H10)2]. However, the high-temperature reactions can be complicated by dehydration of the amide to the corresponding nitrilium derivative [8-EtC≡N-3,3’-Co(1,2-C2B9H10)(1’,2’-C2B9H11)], followed by addition reaction of the BH group of the adjacent dicarbollide ligand to the activated -C≡N+- triple bond, which leads to the formation of 8,8’-N,C-bridged [8,8’-μ-(EtC=HN-N,C)-3,3’-Co(1,2-C2B9H10)2] and 8,4’-N-bridged [8,4’-μ-EtCH=N-3,3’-Co(1,2-C2B9H10)2] derivatives. Heating [8-Et(HO)C=HN-3,3’-Co(1,2-C2B9H10)(1’,2’-C2B9H11)] in boiling nitrobenzene gives amidine [8-PhNHC(Et)=HN-3,3’-Co(1,2-C2B9H10)(1’,2’-C2B9H11)] as the major reaction product.
