123264-41-5Relevant articles and documents
Synthesis and chemistry of cationic alkyl, alkenyl, and allyl complexes derived from the soluble, cationic hydride (C5H4Me)2Zr(H)(THF)+
Jordan, Richard F.,LaPointe, Robert E.,Bradley, Prudence K.,Baenziger, Norman
, p. 2892 - 2903 (2008/10/08)
Reaction of Cp′2Zr(CH2Ph)2 (Cp′ = C5H4Me) with [Cp′2Fe] [BPh4] in THF produces the cationic benzyl complex [Cp′2Zr(CH2Ph)(THF)] [BPh4] (4) which contains a normal η1-benzyl ligand. Hydrogenolysis of 4 in THF solution (1 atm of H2, 23°C) produces the soluble cationic hydride complex [Cp′2Zr(H)-(THF)][BPh4] (5). Hydride 5 reacts with olefins H2C=CH2R to yield cationic alkyl complexes [Cp′2Zr-(CH2CH2R)(THF)][BPh4] (8a, R = H; 8b, R = Me; 8c, R = Et), with 2-butyne to give the cationic 2-butenyl complex [Cp′2Zr(CE)-C(Me)=C(H)(Me)}(THF)][BPh4] (9), and with allene to give the allyl complex [Cp′2Zr(η3-C3H 6)(THF)][BPh4] (13). Solutions of 4, 5, or 13 in CH2Cl2 catalyze the polymerization of ethylene to polyethylene. Solutions of 5 and of 8a,c in THF catalyze the oligomerization of ethylene to butene, hexene, and octene. Alkyl complexes 8a-c also insert 2-butyne to give cationic alkenyl complexes [Cp′2Zr{(Z)-C(Me)=C(Me)(R)}(THF)][BPh4] (10a, R = Et; 10b, R = nPr; 10c, R = nBu). No evidence for multiple 2-butyne insertion or for competing β-H elimination reactions is observed. The structure of the cationic alkenyl complex [Cp′2Zr{(Z)-C(Me)=C(Me)(nPr)}(THF)] [BPh4] (10b) has been determined by X-ray diffraction. Complex 10b crystallizes in space group P21/n with a = 12.084 (4) A?, b = 20.469 (9) A?, c = 16.436 (2) A?, β= 100.26 (2)°, V = 4000 (2) A?3, and Z = 4. The alkenyl ligand lies in the plane between the two Cp′ ligands in the exo conformation, and the THF ligand is rotated 50° from the optimum conformation for Zr-O π bonding.
