Center-to-propeller and propeller-to-propeller stereocontrol in a series of macrobicyclic tri-λ5-phosphazenes

Center-to-propeller stereocontrol in a family of macrobicyclic, double-propeller shaped tri-λ5-triphosphazenes remains constant in the upper tribenzylamine fragment as the size of the pivotal group at the lower tris(phosphane) fragment is gradually increased. In contrast the propeller-to-propeller stereocontrol diminishes as a result of the increasing conformational lability in the lower hemisphere.