Synthesis and Structure of New Carborane‐Substituted Cyclotriphosphazenes

The reactions of [N 3 P 3 Cl 6 ] with one, two, or three equivalents of the difunctional 1,2‐ closo ‐carborane C 2 B 10 H 10 {CH 2 OH} 2 and K 2 CO 3 in acetone have been investigated. These reactions led to the new spiro‐closo ‐carboranylphosphazenes gem ‐[N 3 P 3 Cl 6−2 n {(OCH 2 ) 2 C 2 B 10 H 10 } n ] ( n =1 ( 1 ), 2 ( 2 )) and the first fully carborane‐substituted phosphazene gem ‐[N 3 P 3 {(OCH 2 ) 2 C 2 B 10 H 10 } 3 ] ( 3 ). A bridged product, non‐gem ‐[N 3 P 3 Cl 4 {(OCH 2 ) 2 C 2 B 10 H 10 }] ( 4 ), was also detected. The reaction of the well‐ known spiro derivatives [N 3 P 3 Cl 2 (O 2 C 12 H 8 ) 2 ] and [N 3 P 3 Cl 4 (O 2 C 12 H 8 )] with the same carborane‐diol and K 2 CO 3 in acetone gave the new compounds gem ‐[N 3 P 3 (O 2 C 12 H 8 ) 3− n {(OCH 2 ) 2 C 2 B 10 H 10 } n ] ( n =1 ( 5 ) or 2 ( 6 ), respectively), without signs of intra‐ or intermolecularly bridged species. Upon treatment with NEt 3 in acetone, compound 5 was converted into the corresponding nido ‐carboranylphosphazene. However, the reaction of gem ‐[N 3 P 3 (O 2 C 12 H 8 ) 2 {(OCH 2 ) 2 C 2 B 10 H 10 }] ( 5 ) with NEt 3 in ethanol instead of acetone proceeded in a different manner to give the new compound (NHEt 3 ) 2 [N 3 P 3 (O 2 C 12 H 8 ) 2 (O){OCH 2 C 2 B 9 H 10 CH 2 OCH 2 CH 3 }] ( 7 ). For compounds with two 2,2′‐dioxybiphenyl units, gem ‐[N 3 P 3 (O 2 C 12 H 8 ) 2 {(OCH 2 ) 2 C 2 B 10 H 10 }] ( 5 ), (NHEt 3 )[N 3 P 3 (O 2 C 12 H 8 ) 2 {(OCH 2 ) 2 C 2 B 9 H 10 }] ( 8 ), and (NHEt 3 ) 2 [N 3 P 3 (O 2 C 12 H 8 ) 2 (O){OCH 2 C 2 B 9 H 10 CH 2 OCH 2 CH 3 }] ( 7 ), a mixture of different stereoisomers may be expected. However, for 5 and 7 only the meso compounds seem to be formed, with the same ( R , S )‐configuration as in the precursor [N 3 P 3 Cl 2 (O 2 C 12 H 8 ) 2 ]. The reaction of 5 to give 8 seems to proceed with a change of configuration at one phosphorus center, giving a racemic mixture. The crystal structures of the nido ‐carboranylphosphazenes 7 and 8 have been confirmed by X‐ray diffraction methods.