Crystal and molecular structure of (-)-(S)- and (+)-(R)-bromofosfamide

The crystal and molecular structures of(-)-(S)- and (+)-(R)-bromofosfamide were determined as a part of our research on therapeutically useful oxazaph osphorines. Both compounds crystallized in strictly enantiotropic crystals. The six-membered oxazaphosphorine ring adopts chair-forms with P=O phospho ryl oxygen atom in equatorial orientation. Two halogen atoms (Cl and Br) at the terminus of aminoethyl substituents are differently anchored in the cr ystals. The crowded surrounding of around chlorine atom results in a H-bond formation of Cl...H-C, while bromine atom is much more separated from H-at om. Both compounds undergo partial decomposition during diffractometric exp osition with emission of free bromine.