Titanium complexes of bis(1 degrees-amido)cyclodiphosph(III)azanes and bis(1 degrees-amido)cyclodiphosph(V)azanes: facial versus lateral coordination

Bis(1 degrees -amino)cyclodiphosph(III)azanes and bis(1 degrees -amino)cycl odiphosph(V)azanes show different coordination preferences with titanium(IV ). The bis(tert-butylamino)cyclodiphosph(III)azane cis-[Bu-t(H)N((BuNP)-N-t )(2)N(H)Bu-t] (1) reacts with TiCl4 to afford {[((BuNP)-N-t)(2)(NBut)(2)]Ti Cl2} (2), in which the ligand chelates the metal as a diamide, above the he terocycle. Oxidations of 1 with phenyl- or p-tolyl azide yield the cyclodip hosph(V)azanes cis-[Bu-t(H)N(ArN=PNBut)(2)N(H)Bu-t] (Ar = phenyl (3), p-tol yl (4)). Single-crystal X-ray studies of 3 and 4 reveal structures similar to those of their parent cyclodiphosph(III)azanes, but with pendent arylimi no groups attached to the phosphorus(V) atoms. When 3 and 4 are allowed to react with TiCl4 the complexes {[Bu-t(H)N(ArN=PNBut)(2)NBut]TiCl3} (Ar = ph enyl (5), p-tolyl (6)) are isolated. In these compounds the cyclodiphosph(V )azanes coordinate the metal laterally as monoanionic N-P-N ligands, simila r to phosphoranates. An analogous side-on coordination is also found for th e dichalcogeno complexes {[Bu-t(H)N(E=PNBut)(2)NBut]TiCl3} (E = S (9), Se ( 10)).