Phosphorus−Nitrogen Donor Interaction Leading to Atrane Formation in Phosphate and Oxyphosphorane Compositions. Implications for Phosphoryl Transfer Enzymes¹

Reaction of aminotriphenols, tris(2-hydroxy-3,5-dimethylbenzyl)amine (E) and tris(2- hydroxy-3-tert-butyl-5-methylbenzyl)amine (F), with triphenylphosphite, tris(p-methoxyphenyl)phosphite, or phenyldiphenoxyphosphane in the presence of N-chlorodiisopropylamine led to the isolation of tetraoxyphosphorane 1, pentaoxyphosphorane 3, phosphate-atrane 2, hexacoordinated pentaoxyphosphorane-atrane 4, and the first hexacoordinated tetraoxyphosphorane-atrane 5. X-ray analysis of 1−3 and 5 were obtained. NMR data is reported and supports that the atrane 4 has the same hexacoordinated structure as 5. Phosphate 2 reveals weak phosphorus−nitrogen donor action whereas the hexacoordinated atranes 4 and 5 have pronounced P−N coordination. The results are used to support amino acid donor action occurring at active sites of phosphoryl transfer enzymes. Increased strength of donor action in the higher-coordinate model activated state compared to that in the substrate phosphate composition should serve as a factor in enhancing enzyme reaction rates.