The solid state structure and reactivity of NbCl(5)center dot(N,N '-dicyclohexylurea) in solution: evidence for co-ordinated urea dehydration to the relevant carbodiimide (Articolo in rivista)

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  • The solid state structure and reactivity of NbCl(5)center dot(N,N '-dicyclohexylurea) in solution: evidence for co-ordinated urea dehydration to the relevant carbodiimide (Articolo in rivista) (literal)
Anno
  • 2010-01-01T00:00:00+01:00 (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#doi
  • 10.1039/c001669a (literal)
Alternative label
  • Michele Aresta (1,2); Angela Dibenedetto (1,2); Paolo Stufano (1,2); Brunella Maria Aresta (3), Sabino Maggi (3); Imre Papai (4); Tibor Andras Rokob (4); Bartolo Gabriele (5) (2010)
    The solid state structure and reactivity of NbCl(5)center dot(N,N '-dicyclohexylurea) in solution: evidence for co-ordinated urea dehydration to the relevant carbodiimide
    in Dalton transactions (2003. Print); Royal Society of Chemistry, Cambridge (Regno Unito)
    (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori
  • Michele Aresta (1,2); Angela Dibenedetto (1,2); Paolo Stufano (1,2); Brunella Maria Aresta (3), Sabino Maggi (3); Imre Papai (4); Tibor Andras Rokob (4); Bartolo Gabriele (5) (literal)
Pagina inizio
  • 6985 (literal)
Pagina fine
  • 6992 (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#url
  • http://pubs.rsc.org/en/Content/ArticleLanding/2010/DT/c001669a (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#numeroVolume
  • 39 (literal)
Rivista
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#pagineTotali
  • 8 (literal)
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  • 30 (literal)
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  • Scopu (literal)
  • ISI Web of Science (WOS) (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni
  • (1) Department of Chemistry, University of Bari, I-70126 Bari, Italy; (2) CIRCC Bari, I-70126 Bari, Italy; (3) CNR-IC, Institute of Cristallography, I-70126 Bari, Italy; (4) Chemical Research Center, Hungarian Academy of Sciences, H-1525 Budapest, Hungary; (5) Department of Pharmaceutical Sciences, University of Calabria, I-87036 Arcavacata di Rende (CS), Italy (literal)
Titolo
  • The solid state structure and reactivity of NbCl(5)center dot(N,N '-dicyclohexylurea) in solution: evidence for co-ordinated urea dehydration to the relevant carbodiimide (literal)
Abstract
  • NbCl(5)center dot(N,N '-dicyclohexylurea) 1a owns a distorted octahedral structure due to intramolecular NH center dot center dot center dot Cl bonding. The unit cell contains four units which are intermolecularly NH center dot center dot center dot Cl and NH center dot center dot center dot N bonded. An extended intramolecular network of H-bonding (N-H center dot center dot center dot Cl, CH center dot center dot center dot Cl, CH center dot center dot center dot N) causes the 3D self assembling of the units. Upon addition of base, the HCl release from 1a is observed with the transfer to Nb of the O-atom of the carbonylic function of the starting urea which is converted into the relevant carbodiimide CyN=C=NCy 4. The latter is quantitatively released by adding an excess of NEt(3) at 308 K (py and DBU are less efficient) with formation of the known NbOCl(3)(NEt(3))(2), isolated in quantitative yield. Increasing the temperature leads to a loss in selectivity as the formed DCC undergoes further reactions. At 350 K, the isocyanate CyN=C=O has been isolated in 60% yield besides a mixture of Nb-complexes. DFT calculations have been coupled to IR and NMR experiments for characterizing possible reaction intermediates and the behaviour of 1a. Several other MCl(x) species (ScCl(3), YCl(3), LaCl(3), TiCl(4), TaCl(5), AlCl(3), SnCl(4)) have been shown to be able to co-ordinate DCU but not all of them promote the conversion of urea into DCC. (literal)
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