Stabilization of acyclic phosphazides using the ortho-closo-dicarbadodecaboranyl residue.

The reactions of triphenylphosphine with the azido-ortho-closo-dicarbadodecaboranes 1-N(3)-2-R-closo-1,2-C(2)B(10)H(10) [R = Me (1a), Ph (1b)] produce the stable and isolatable carboranyl phosphazides 1-(N(3)PPh(3))-2-R-closo-1,2-C(2)B(10)H(10) [R = Me (2a), Ph (2b)] in good yields. Single crystal X-ray diffraction analysis revealed that, in the solid state, phosphazide 2a adopts an unusual s-cis conformation, whereas 2b adopts an s-trans conformation.