Neutral and Cationic Rare Earth Metal Alkyl and Benzyl Compounds with the 1,4,6-Trimethyl-6-pyrrolidin-1-yl-1,4-diazepane Ligand and Their Performance in the Catalytic Hydroamination/Cyclization of Aminoalkenes

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A new neutral tridentate 1,4,6-trimethyl-6-pyrrolidin-1-yl-1,4-diazepane (L) was prepared. Reacting L with trialkyls M(CH(2)SiMC(3))(3)(THF)(2) (M = Sc, Y) and tribenzyls M(CH(2)Ph)(3)(THF)(3) (M = Sc, La) yielded trialkyl complexes (L)M(CH(2)SiMe(3))(3) (M = Sc, 1; M = Y, 2) and tribenzyl complexes (L)M(CH(2)Ph)(3) (M = Sc, 3; M = La, 4). Complexes I and 2 can be converted to their corresponding ionic compounds [(L)M(CH(2)SiMe(3))(2)(THF)][B(C(6)H(5))(4)] (M = Sc, 5; M = Y, 6) by reaction with [PhNMe(2)H] [B(C(6)H(5))(4)] in THE Complexes 3 and 4 can be converted to cationic species [(L)M(CH(2)Ph)(2)](+) by reaction with [PhNMe(2)H][B(C(6)F(5))(4)] in C(6)D(5)Br in the absence of THE The neutral complexes 1-4 and their cationic derivatives were studied as catalysts for the hydroamination/cyclization of 2,2-diphenylpent-4-en-1-amine and N-methylpent-4-en-1-amine reference substrates and compared with ligand-free Sc, Y, and La neutral and cationic catalysts. The most effective catalysts in the series were the cationic L-yttrium catalyst (for 2,2-diphenylpent-4-en-1-amine) and the cationic lanthanum systems (for N-methylpent-4-en-1-amine). For the La catalysts, evidence was obtained for release of L from the metal during catalysis.