Monosubstituted uranocenes

Least Squares Linear Regression Analysis of VT H NMR Data for Ring Protons in Uranocene, Octamethyluranocene and the Unsubstituted Ring in Monosubstituted Uranocenes. 

C. Monosubstituted UrariOCeheg. Some monosubstituted uranocenes are known, compounds with one COT and one substituted COT ligands. The mono-t-butoxycarbonyluranocene, 42, was prepared by reaction of one mole of the corresponding COT dianion with one mole of COT dianion itself and UC14(4 ). It could be separated from the disubstituted compound, 41, also formed, by its greater stability towards hydrolysis. Mono-t-butyluranocene, 32, was obtained and measured as a 1.8 1 mixture with the disubstituted compound, 33. A separate preparation of pure 33 allowed complete analysis of the mixture. Mono-(di-t-butylphosphino)uranocene has also been reported by Fischer, et al(45). 

The importance of these compounds for nmr interpretations is that we can look at the unsubstituted ring in systems where Xx and Xy are not constrained by symmetry to be equal. In both of the monosubstituted uranocenes investigated, the proton resonance of the unsubstituted ring is a singlet. 

Recently, Fischer (15/45) has independently arrived at the same conclusion based on the temperature dependence behavior of the H NMR resonances of the two monosubstituted uranocenes,... 

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