In this study, the step‐wise synthesis to a series of higher phosphoramidates was explored, affording compounds containing N−P−N, symmetric and asymmetric P−N−P and P−N−P−N−P linkages. Salt elimination and lithiation strategies were employed to create the new P−N bonds. It was found that the steric bulk and electronic contribution of the substituents on the P(V) centers were important factors to the success of the reactions. The oligomeric phosphoramidates were characterized by multinuclear NMR and IR spectroscopies as well as ESI mass spectrometry. A selection of the synthesized P−N oligomers were evaluated for their antimicrobial activity against E.coli, S.aureus, C.albicans, and A.fumigatus at varying concentrations. The results suggest their potential use as environmentally friendly fire retardants as the minimal inhibitory concentration (MIC) value for all the compounds was found to be >128 μM, indicating that the compounds do not have any detectable antimicrobial activity.

The Cover Feature shows the stepwise synthesis of oligomeric phosphoramidates. A series of compounds having P–N, N–P‐N, P–N–P and P–N–P–N–P linkages were prepared via salt elimination and lithiation strategies and characterized using various spectroscopic techniques. These are postulated to be biocompatible, hydrolytically degradable at low pH and flame retardant – useful properties for many applications. A selection of the P–N compounds were screened for antimicrobial activity at various concentrations. The authors acknowledge Blake Laing‐Smith for this creative artwork. More information can be found in the Full Paper by E. M. Leitao et al.