In this paper we report on the synthesis, characterization and reactivity of NbCl5(N,N'-dicyclohexylurea), describe its structure, discuss the unique mode of bonding of urea to Nb and show the presence in the solid state of different H-bondings. Very interestingly when NbCl5.(N,N'-Dicyclohexylurea) was treated with an excess of base at 300 K, we observed the immediate formation of the dehydrated form of the urea, i.e. dicyclohexylcarbodiimide, and of NbOCl3.So far in the literature are reported examples in which toxic reagents such as phosgene1-4 or PCl52 or SOCl23 were used with a low selectivity and a complex work-up of the reacting mixture. In our study the dewatering reaction using Group 4 and 5 metal halides and other metals in their highest oxidation state is performed quite easily, under very mild conditions (300 K) with high conversion yield (>98%) and selectivity (100%).1.      a) Hussenet, P.; Le Goff, P.; Sennyey, G., US Patent 5 648 537, 1997; b) Lawton, L. E., US Patent 3 972 933, 1976.2.      a) Schlama, T.; Governeur, V.; Mioskowski, C., Tetrahedron Letters, 1996, 37, 7074; b) Williams, A.; Ibrahim, I. T., Chem. Rev. 1981, 81, 589; c) Amiard, G.; Heymes, R.; Velluz, L., Chem. Abstr. 1958, 52, 426. CD2Cl2, 600 MHz; d) Eilingsfeld, H.; Seefelder, M.; Weidinger, H., Angew. Chem. 1960, 72, 836.3.      a) Ulrich, H.; Sayigh, A. A. R., J. Org. Chem. 1965, 30, 2779; b) Ulrich, H.; Sayigh, A. A. R., Angew. Chem. Internat. Edit. 1966, 5, 8.4.      Stevens, C. L.; Singhal, G. H.; Ash, A. B., J. Org.Chem. 1967, 32, 2895.

Molecular structure and reactivity in solution of NbCl<sub>5</sub><sup>.</sup>(N,N'-dicyclohexylurea)

239th National Meeting (2010)

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Molecular structure and reactivity in solution of NbCl5.(N,N'-dicyclohexylurea)

Molecular structure and reactivity in solution of NbCl₅^.(N,N'-dicyclohexylurea)