New Sandwich and Half-Sandwich Titanium Hydrazido Compounds

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• 作者：Jonathan D. Selby ; Marta Feliz ; Andrew D. Schwarz ; Eric Clot ; Philip Mountford
• 刊名：Organometallics
• 出版年：2011
• 出版时间：April 25, 2011
• 年：2011
• 卷：30
• 期：8
• 页码：2295-2307
• 全文大小：1249K
• 年卷期：v.30,no.8(April 25, 2011)
• ISSN：1520-6041

文摘

New mono- and bis-cyclopentadienyl terminal titanium hydrazido(2鈭? compounds were prepared by tert-butyl imide/N,N-disubstituted hydrazine exchange reactions. Reaction of Cp*Ti(N^tBu)Cl(py) (1) with Ph₂NNH₂ gave the terminal hydrazide Cp*Ti(NNPh₂)Cl(py) (4), whereas the corresponding reaction of CpTi(N^tBu)Cl(py) gave the dimer Cp₂Ti₂(渭-畏¹:畏¹-NNPh₂)(渭-畏²:畏¹-NNPh₂)Cl₂. Reaction of 1 with Me₂NNH₂ (1 equiv) also gave a dimer, Cp*₂Ti₂(渭-畏¹:畏¹-NNMe₂)(渭-畏²:畏¹-NNMe₂)Cl₂ (8), while the reaction with 2 equiv of Me₂NNH₂ gave Cp*Ti(畏²-NHNMe₂)₂Cl (7) containing two 畏²-bound hydrazide(1鈭? ligands. Formation of 7 and 8 proceeds via a common intermediate, Cp*Ti(NH^tBu)(畏²-NHNMe₂)Cl, observed by NMR spectroscopy. Reaction of 4 with LiNHNPh₂ gave the mixed hydrazide(2鈭?/hydrazide(1鈭? derivative Cp*Ti(NNPh₂)(NHNPh₂)(py) (10). The corresponding reaction of 1 formed Cp*Ti(N^tBu)(NHNPh₂)(py), which rearranged to Cp*Ti(NH^tBu)(NNPh₂)(py). The titanocene derivative Cp₂Ti(NNPh₂)(py) (14) was prepared by reaction of Cp₂Ti(N^tBu)(py) (13) with Ph₂NNH₂, whereas the corresponding reaction with Me₂NNH₂ gave mixtures including CpTi(NH^tBu)(渭-畏¹:畏¹-NNMe₂)(渭-畏²:畏¹-NNMe₂)TiCp(畏¹-Cp). The electronic structure of 14 was investigated by DFT and compared to that of the imido complex 13. Whereas the HOMO of the formally 20 valence electron compound 13 is a ligand-centered orbital based both on the Cp rings and on the imido N, in 14 this is the HOMO鈭? and one of the Ti鈺怤_伪 蟺-bonding MOs is the HOMO, destabilized by an N_伪鈭扤_尾 antibonding interaction.