15-Crown-5 (systematic name: 1,4,7,10,13-pentaoxacylopentadecane), C 10 H 20 O 5 , which is liquid at room temperature, has been crystallized using in situ methods. It crystallizes with two different conformers in the asymmetric unit, which differ from those identified in conformational searches based on data mining and computational methods. The molecules interact through face-to-face C-Hร ร รO contacts to form layers which stack along the [001] direction.
Related literature
A crystal of the title compound was grown according to the method of Boese & Nussbaumer (1994). Hill & Feller (2000) studied conformations of the compound using ab initio methods, identifying 16 low-energy conformers, though none of these appear to match either of those observed here. Raithby et al. (1997) analysed conformers in the Cambridge Structural Database (Allen, 2002), and though regions of the uniangular conformers identified in that study resemble the conformations observed here the agreement is not complete. Hill & Feller (2000) commented that accurate prediction of low-lying conformations in floppy molecules is a challenging task, and the presence of intermolecular C-Hร ร รO interactions in the title compound, though weak, could well alter computational energy rankings derived for isolated molecules.
Experimental
Crystal data C 10 H 20 O 5 M r = 220.27 Tetragonal, P4 1 a = 8.79540 (10) A c = 30.0676 (10) A V = 2326.00 (9) A ห3 Z = 8 Mo K radiation = 0.10 mm ร1 T = 120 K 1.00 ร 0.30 ร 0.30 mm Data collection Bruker SMART APEX CCD areadetector diffractometer Absorption correction: multi-scan (SADABS; Sheldrick, 2007) T min = 0.73, T max = 0.97 24253 measured reflections 2414 independent reflections 1996 reflections with I > 2(I) R int = 0.052 Refinement R[F 2 > 2(F 2 )] = 0.043 wR(F 2 ) = 0.084 S = 0.95 2414 reflections 271 parameters 1 restraint H-atom parameters not refined ร max = 0.20 e A หร3 ร min = ร0.16 e A หร3 Data collection: SMART (Siemens, 1993); cell refinement: SAINT (Siemens, 1995); data reduction: SAINT; program(s) used to solve structure: SIR92 (Altomare et al., 1994); program(s) used to refine structure: CRYSTALS (Betteridge et al., 2003); molecular graphics: XP (Sheldrick, 1997); software used to prepare material for publication: CRYSTALS.