Synthesis and characterization of Cp{sub 2}Zr(CH(Me)(6-ethylpyrid-2-yl)) (CO){sup +}, a d{sup 0} metal alkyl carbonyl complex. Coordination chemistry of the four-membered azazirconacycle Cp{sub 2}Zr({eta}{sup 2}-C,N-CH(Me)(6-ethylpyrid-2-yl)){sup +}
- Univ. of Iowa, Iowa City, IA (United States)
The cationic complex Cp{sub 2}Zr(CH{sub 3})(THF){sup +} (1, as the BPh{sub 4}{sup {minus}} salt) reacts with 2,6-diethylpyridine to afford the chelated secondary zirconocene-alkyl complex Cp{sub 2}Zr({eta}{sup 2}-C,N-CH(Me)(6-ethylpyrid-2-yl)){sup +} (2). Treatment of complex 2 with CO, CH{sub 3}CN, {sup t}BuCN, and (PhCH{sub 2})(Et){sub 3}N{sup +}Cl{sup {minus}} affords Cp{sub 2}Zr(CH(Me)(6-ethylpyrid-2-yl))(CO){sup +} (3), Cp{sub 2}Zr(CH(Me)(6-ethylpyrid-2-yl))(CH{sub 3}CN){sup +} (4), Cp{sub 2}Zr(CH(Me)(6-ethylpyrid-2-yl))({sup 5}BuCN){sup +} (5), and Cp{sub 2}Zr(CH(Me)(6-ethylpyrid-2-yl))(Cl) (6), respectively. The thermally sensitive d{sup 0} carbonyl complex 3 is a rare example of a d{sup 0} M(alkyl)-CO adduct and is unambiguously characterized in solution by low-temperature NMR and IR spectroscopy, {sup 13}C-labeling and hydrolysis experiments, and decomposition studies. IR and NMR data establish that 3 contains a terminal CO ligand. An X-ray structure analysis of 6 established that the CH(Me)(6-ethylpyrid-2-yl) ligand adopts a chelated structure; the similarity of the spectroscopic data for 3-6 implies that 3-5 have similar chelated structures. At room temperature, 3 in CD{sub 2}Cl{sub 2} rapidly decomposes to afford a complex mixture of products. {sup 1}H NMR monitoring of the decomposition of 3 reveals formation of a transient cationic zirconocene-acyl intermediate 9, which undergoes 1,2-H shift to afford a mixture of isomeric/oligomeric zirconocene-enolates. Treatment of this mixture with (PhCH{sub 2})(Et){sub 3}N{sup +}Cl{sup {minus}} affords Cp{sub 2}Zr(OCH=C(Me)(6-ethylpyrid-2-yl)) Cl (10) as a mixture of E/Z isomers, establishing the presence of zirconocene-enolate species. Hydrolysis of the decomposition products of 3 affords a mixture of thermally sensitive tautomers, enol 11/aldehyde 11{prime}, which are characterized by NMR, FTIR, and mass spectroscopy. 39 refs., 6 figs., 3 tabs.
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- FG05-89ER75503
- OSTI ID:
- 569221
- Journal Information:
- Journal of the American Chemical Society, Journal Name: Journal of the American Chemical Society Journal Issue: 23 Vol. 114; ISSN JACSAT; ISSN 0002-7863
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
40 CHEMISTRY
ACTIVATION ENERGY
ALDEHYDES
ALKALI METAL COMPLEXES
ALKYL RADICALS
BPH
CARBONYL RADICALS
CARBONYLATION
CHELATES
CHEMICAL ACTIVATION
COORDINATION NUMBER
COORDINATION VALENCES
DECOMPOSITION
DESIGN
ENOLS
HYDROLYSIS
INFRARED SPECTROMETERS
ISOMERS
LIGANDS
MASS SPECTROMETERS
MOLECULAR STRUCTURE
NMR SPECTROMETERS
ORGANOMETALLIC COMPOUNDS
SYNTHESIS