1-Benzoylazoles: an experimental NMR and crystallography) and theoretical study R.M. Claramunt a , P. Cornago a , D. Sanz a , M.D. Santa-Marõ Âa a , C. Foces-Foces b , I. Alkorta c , J. Elguero c, * a Departamento de Quõ Âmica Orga Ânica y Biologõ Âa, Facultad de Ciencias, UNED, Senda del Rey 9, 28040 Madrid, Spain b Departamento de Cristalografõ Âa, Instituto de Quõ Âmica-Fõ Âsica Rocasolano, CSIC, Serrano 119, 28006 Madrid, Spain c Instituto de Quõ Âmica Me Âdica, Centro de Quõ Âmica Orga Ânica `Manuel Lora Tamayo', CSIC, Juan de la Cierva 3, 28006 Madrid, Spain Received 30 April 2001; revised 12 June 2001; accepted 12 June 2001 Abstract Five N-benzoylazoles imidazole, pyrazole, indole, benzimidazole and carbazole) have been prepared following modi®ed literature procedures. Their NMR spectra in solution  1 H, 13 C and 15 N) have been measured. The crystal structures of 1- benzoylindole and 9-benzoylcarbazole have been determined by X-ray crystallography and the corresponding 13 CNMRspectra in the solid state have been measured by the CPMAS technique. Whereas 1-benzoylindole presents a standard behaviour, 9- benzoylcarbazole shows an unexpected 13 C CPMAS spectrum with additional splittings. In order to understand this fact, the 1 H and 13 C NMR spectra in dimethylether at 21438C 130 K) have been recorded and ab initio calculations RHF/6-311G**) carried out. The corresponding absolute shieldings GIAO/ RHF/6-311G**) together with the X-ray structure and the 13 C chemical shifts at low temperature have been used to discuss the CPMAS spectrum. We propose that the supplementary splittings of this spectrum are due to its conglomerate structure. q 2002 Elsevier Science B.V. All rights reserved. Keywords: Azolides; NMR; CPMAS NMR; Rotational barriers; X-ray crystallography; ab initio calculations 1. Introduction We have been studying the physico±chemical prop- ertiesofazolidesforalongtime.Thesestudiesconcern mainly their NMR properties, generally in solution [1± 5], but also in the solid state [6], and their behaviour in mass spectrometry [7,8]. Recently, we have written a review [9] and a subsequent paper on ab initio calcula- tions of their NZCHO, NZCOCH 3 , NZCOCF 3 and NZCO 2 CH 3 derivatives [10]. The present work reports the results we have obtained for ®ve N-benzoylazoles: namely, 1-benzoy- limidazole 1, 1-benzoylpyrazole 2, 1-benzoylindole 3, 1-benzoylbenzimidazole 4 and 9-benzoylcarbazole 5. Journal of Molecular Structure 605 2002) 199±212 0022-2860/02/$ - see front matter q 2002 Elsevier Science B.V. All rights reserved. PII: S0022-286001)00759-1 www.elsevier.com/locate/molstruc * Corresponding author. Tel.: 134-91411-0874; fax: 134-91564- 4853. E-mail address: iqmbe17@iqm.csic.es J. Elguero).