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(CROSS-CONJUGATED DIENYL)TRICARBONYLIRON CATIONS .2. 4-METHYL DERIVATIVES
被引:25
作者:
BONAZZA, BR
[1
]
LILLYA, CP
[1
]
MAGYAR, ES
[1
]
SCHOLES, G
[1
]
机构:
[1] UNIV MASSACHUSETTS,DEPT CHEM,AMHERST,MA 01003
关键词:
D O I:
10.1021/ja00509a016
中图分类号:
O6 [化学];
学科分类号:
0703 ;
摘要:
Tricarbonyl(cross-conjugated dienyl)iron cations have been generated from precursor alcohols in strong acid solutions and studied by NMR spectroscopy in the temperature range 0 to -50°C. The 4-anti-methyl cation (11) coordinates reversibly, but slowly, with fluorosulfonate ion to give the adduct 12. Broadening of1H and13C NMR signals in the region -40 to -9°C demonstrates rotation about the C2-C3bond of 11. The observations exclude 12 as an intermediate in the rotation process. Relief of steric strain associated with the 4-anti-methyl enhances the driving force for FS03coordination and lowers the barrier for C2-C3rotation. The 4-syn-methyl cation (15) does not give a fluorosulfonate adduct and fails to exhibit NMR signal broadening caused by C2-C3rotation at temperatures below 0°C. Neither cation coordinates with carbon monoxide. Lack of evidence of coordinative unsaturation and the substantial barrier to C2-C3rotation rule out the η3-allyl type structure predicted by the simplest (one interaction) frontier orbital model. © 1979, American Chemical Society. All rights reserved.
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页码:4100 / 4106
页数:7
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