691888-07-0Relevant articles and documents
β-diketiminato scandium chemistry: Synthesis, characterization, and thermal behavior of primary amido alkyl derivatives
Knight, Lisa K.,Piers, Warren E.,Fleurat-Lessard, Paul,Parvez, Masood,McDonald, Robert
, p. 2087 - 2094 (2008/10/09)
Treatment of the β-diketiminato-supported scandium dichlorides {[ArNC(R)CHC(R)NAr]-ScCl2}n (Ar = 2,6-iPr 2-C6H3; R = CH3, 1a, n = 2; R = tBu, 1b, n = 1) with 1 equiv of a lithium amide reagent LiN(H)R′ (R′ = tBu, 2,6-iPr2-C 6H3) gave scandium amido derivatives. For 1a, use of LiN(H)tBu leads to the bis-amido derivative (6a) regardless of the equivalency of amide reagent employed, suggesting that facile ligand redistribution processes are operative when the ligand is the less bulky methyl-substituted example. For 1b, mono-amido chlorides 2b (R′ = tBu) and 3b (R′ = 2,6-iPr2-C 6H3) are obtained in good yields, and these compounds can be alkylated with MeLi to provide mono-amido methyl compounds 4b (R′ = tBu) and 5b (R′ = 2,6-iPr2-C 6H3). All four of these compounds were characterized crystallographically. The amido ligand occupies the exo coordination site exclusively, and there is no evidence in solution for a diastereomer with the amido group in the endo site. DFT calculations suggest that there is a strong steric preference and a slight electronic bias for the amido ligand to assume the exo position. Thermolysis of the amido methyl complex 4b leads to loss of CH4 and production of a scandacylic product, 7, formed via metalation with one of the N-aryl isopropyl methyl groups. This compound was characterized crystallographically. Deuterium labeling experiments suggest that 7 is produced via direct metalation and does not form via a scandium imido intermediate.
