The synthesis of phosphino-terminated dendrimers is described up to the tenth generation, which possess more than 3000 phosphino groups (3-[G(10)’]). Several complexation reactions of these dendrimers toward various low oxidation states transition metal derivatives have been carried out, up to generation 5 for iron (4-[G(5)’] : 96 Ph2P-->Fe(CO)(4) groups), generation 4 for tungsten (5-[G(4)’] : 48 Ph2P-->W(CO)(5) groups), generation 10 for gold (6-[G(10)’] : 3072 Ph2P-->Au-Cl groups), and generation 6 for rhodium (8-[G(6)’] : 192 Ph2P-Rh(acac)(CO) groups). These reactions demonstrate that the phosphino-terminated dendrimers behave analogously to monophosphines, in spite of the nanometer size of the high generations.