The nitrido derivative (n-Bu4N)(4)[(PW11O39RuN)-N-VI] transfers its nitrogen atom to triphenylphosphine to give quantitatively the bis(triphenylphosphane)iminium cation [Ph3PNPPh3](+). An intermediate can be prepared by the reaction of a single molecule of triphenylphosphine with the polyoxometalate, the iminophosphorane derivative (n-Bu4N)(3)[PW11O39RuV{NPPh3}]. The reactivity of the latter species has been investigated to complete the general scheme of the nitrogen-transfer reaction. By the addition of 1 equiv of hydroxide, [PW11O39RuIII{N(OH)PPh3}](4-) is obtained. The reaction can be reversed by the addition of one proton. The phosphinoxime derivative [PW11O39RuIII{N(OH)PPh3}](4-) can be prepared in solution but is unstable. It decomposes to yield quantitatively (n-Bu4N)(4)[PW11O39RuIII{OPPh3}]. All of those species have been thoroughly characterized by mass spectrometry, paramagnetic P-31 NMR, IR, Raman, UV-visible, XANES, and EXAFS spectroscopies.