Two new water-soluble derivatives of 1,3,5-triaza-7-phosphaadamantane (PTA): Synthesis,characterization, X-ray analysis and solubility studies of 3,7-diformyl-1,3,7-triaza-5-phosphabicyclo[3.3.1]nonane and 1-pyridylmethyl-3,5-diaza-1-azonia-7-phosphatricyclo[3.3.1.1]decane bromide

Two water-soluble phosphines, 3,7-diformyl-1,3,7-triaza-5-phosphabicyclo3.3.1]nonane (1, DFPTA) and 1-pyridylmethyl-3,5-diaza-1-azonia-7-phosphatricyclo3.3.1.1]decane bromide (2, pymePTA]Br), have been respectively, prepared by reacting 1,3,5-triaza-7-phosphaadamantane (PTA) with formic anhydride and bromomethylpyridine. Compound 1 is only the second acyl derivative of PTA to be prepared while 2 is only the second derivative of PTA reported that contains an aromatic appendage. Both compounds were characterized by elemental analysis, FAB-MS, ¹H, ¹³C, and ³¹P NMR spectroscopy, and single crystal X-ray diffraction. This analysis showed that the formamide groups of 1 were in an anti confirmation in solution but in a syn confirmation in the solid state. The solubilities of 1 and 2 were examined in common organic solvents and water. It was found that 1.1 M aqueous solutions of 1 could be prepared while 2.4 M solutions of 2 were produced. The greater solubility of 2 was likely due to its ionic nature.