Abstract
In course of the synthesis of phosphonic derivatives of bestatine, several products have been obtained. One of them turned out to occur in two polymorphic forms. Two crystal structures correspond to two molecular conformations. The crystal structures are as follows: (1a) C24H21N2O9P, P21/n, a=8.023(2)Å,b=12.092(2)Å,c=24.103(5)Å,β=92.39(3)°, Z=4, (1b) C24H21N2O9P, P21/c, a=8.322(1)Å,b=16.378(2)Å,c=18.442(2)Å,β=101.13(1)°, Z=4.The main conformational difference consists in the mutual orientation of two phthalyl rings. The conformation and packing of sterically overcrowded and conformationally flexible molecules seem to be stabilized by very weak C–H⋯O hydrogen bonds. The extremely large thermal vibration amplitudes of the phosphonic group's atoms indicate the occurrence of disorder, probably of dynamical character. This disorder becomes frozen below room temperature. The differential scanning calorimetry (DSC) revealed the occurrence of phase transitions below room temperature in both crystals.
Sign-in/Register to access full text options 
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 callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
