342655-84-9Relevant academic research and scientific papers
Pentamethylcyclopentadienyl zirconium and hafnium polyhydride complexes: Synthesis, structure, and reactivity
Visser, Cindy,Van Den Hende, Johannes R.,Meetsma, Auke,Hessen, Bart,Teuben, Jan H.
, p. 1620 - 1628 (2008/10/08)
The half-sandwich zirconium and hafnium N,N-dimethylaminopropyl complexes Cp*M[(CH2)3NMe2]Cl2 (Cp* = η5-C5Me5, M = Zr, 1; Hf, 2) and Cp*M[(CH2)3NMe2]2Cl (M = Zr, 3; Hf, 4) were synthesized by mono- or dialkylation of Cp*MCl3 with the corresponding alkyllithium and Grignard reagents. Hydrogenolysis of the monoalkyl species resulted in the formation of the polyhydride complexes Cp*3M3(μ-H)(μ-Cl)2Cl3 (M = Zr, 5; Hf, 6) and Cp*MCl3. A crystal structure determination of Cp*3Hf3H4Cl5 (6) revealed a fully asymmetric trinuclear structure with three widely differing Hf?Hf distances. Reaction of Cp*3M3H4Cl5 with PMe3 resulted in fragmentation of the cluster and ligand redistribution to give Cp*MCl3(PMe3) and the dimeric hydride complexes Cp*2M2(μ-H)3Cl3 (PMe3) (M = Zr, 7; Hf, 8), structurally characterized for M = Zr. The trinuclear polyhydride Cp*3Hf3H4Cl5 reacts with 2,6-xylylisocyanide to give three distinct products, a μ-enediamide complex, [Cp*HfCl2]2[μ-xyNCH=CHNxy] (11, xy = 2,6-dimethylphenyl), which was structurally characterized, an imido complex, [Cp*Hf(μ-Nxy)Cl]2 (12), and an azaallyl species, Cp*Hf(η3-CH2CHNxy)Cl2 (13). The reactivity of 6 can be interpreted as proceeding through initial cleavage of the trinuclear complex into the fragments Cp*2Hf2 (μ-H)3Cl3 and Cp*HfHCl2 , followed by the separate reactivity of these fragments.
