Scandium, Yttrium, and Lanthanum Benzyl and Alkynyl Complexes with the <i>N</i>-(2-Pyrrolidin-1-ylethyl)-1,4-diazepan-6-amido Ligand: Synthesis, Characterization, and <i>Z</i>-Selective Catalytic Linear Dimerization of Phenylacetylenes
作者:Shaozhong Ge、Auke Meetsma、Bart Hessen
DOI:10.1021/om8004228
日期:2009.2.9
1,4,6-Trimethyl-N-(2-pyrrolidin-1-ylethyl)-1,4-diazepan-6-amine (HL) reacts with M(CH2Ph)(3)(THF)(3) to give the dibenzyl complexes (L)M(CH2Ph)(2) (M = SC, 1; M = Y, 2; M = La, 3). Compounds 1, 2, and 3 can be converted to their corresponding cationic monobenzyl species [(L)M(CH2Ph)](+) (M = Sc, Y and La) by reaction with [PhNMe2H][B(C6F5)(4)]. Reaction of (L)Sc(CH2Ph)(2) with 2 equiv of phenylacetylene affords the monomeric dialkynyl complex (L)Sc(C CPh)(2) (4), while reactions of (L)M(CH2Ph)(2) (M = Y and La) give the dimeric dialkynyl complexes [(L)M(C CPh)(mu-C CPh)](2) (M = Y, 5; M = La, 6). The neutral complexes (2, 3, 5, and 6) and the cationic monobenzyl species [(L)M(CH2Ph)](+) (M = Y and La) are catalysts for the Z-selective linear head-to-head dimerization of phenylacetylenes. The cationic yttrium and the neutral lanthanum systems are the most effective catalysts in the series. The related scandium species show poor activity and selectivity.