Abstract
The title complex was crystallized from a saturated solution of 18-crown-6 in nitromethane at 5°C and cooled to −150°C prior to X-ray diffraction data collection. At −150° C 18-crown-6·2(CH3NO2) is monoclinic,P21/n witha=9.290(2),b=7.864(6),c=13.627(8) A, β=1000.84(4)° andD calc=1.31 g cm−3 for Z=2. Leastsquares refinement using 1521 independent observed reflections [F o≥5σ(F o)] led to a final conventionalR value of 0.041. The complex at −150°C is isostructural with its room temperature structure with the exception of the orientation of the methyl hydrogen atoms and their crown ether oxygen interactions. The methyl group hydrogen atoms were fully refined isotropically. The crown ether resides around a center of inversion and hasD 3d symmetry. There is one methyl hydrogen...crown interaction at 2.35(3) A, one apparently bifurcated hydrogen bond utilizing a second methyl hydrogen atom (2.55(3), 2.65(3) A) and the third hydrogen atom is actually directed away from the crown ring (closest H...O contact=2.67(3) A).
Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
