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DOI: 10.1039/A701018D (Paper) Reference Section for: J. Chem. Soc., Faraday Trans., 1997, 93, 2503-2507

Structural and spectroscopic investigations of 1,1,3,3-tetrakis(alkylamino)allyl cations, methylene-bis(N,N′-dialkylformamidinium) dications and related formamidine derivatives

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George R. Clark, Clifton E. F. Rickard, Peter W. J. Surman and Michael J. Taylor

Abstract

Treatment of pentachlorocyclopropane under basic conditions with either of the primary amines, PriNH2 or ButNH2, displaces all the chlorine atoms and yields methylene-bis(N,N′-dialkylformamidine), CH2{C(NR)NHR}2 (R=Pri or But). A facile protonation converts the molecule into the 1,1,3,3-tetrakis(alkylamino)allyl cation, [CH{C(NHR)2}2]+ to which a further proton can be added to generate the corresponding methylene-bis(N,N′-dialkylformamidinium) ion. Barriers to rotation about the partial CN double bonds of these dications, [CH2{C(NHR)2}2]2 (R=Pri or But), of 80 and 74 kJ mol-1, respectively, are deduced from variable temperature NMR data. 1H and 13C NMR studies of the kindred methylene-bis(formamidine) molecules show evidence of tautomerism as well as conformational changes in solution. Hydrolysis of methylene-bis(N,N′-di-tert-butylfor mamidine) gives N,N′-di-tert-butylformamidine. The crystallographically determined structure of N,N′-di-tert-butylformamidinium chloride, [CH(NHBut)2]Cl, is compared with other members of this series.

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