Shaozhong Ge, A. Meetsma, B. Hessen
Feb 9, 2009
Citations
0
Influential Citations
43
Citations
Journal
Organometallics
Abstract
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)(μ-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.