Synthesis of [(HIPTNCH2CH2)3N]V compounds (HIPT=3,5-(2,4,6-i-Pr3C6H2)2C6H3) and an evaluation of vanadium for the reduction of dinitrogen to ammonia

Green [HIPTN3N]V(THF) ([HIPTN3N](3-)) = [(HIPTNCH2CH2)(3)N](3-), where HIPT = 3,5-(2,4,6-i-Pr3C6H2)(2)C6H3) can be prepared in a 70-80% yield via the addition of H-3[HIPTN3N] to VCl3(THF)(3) in THF, followed by the addition of LiN(SiMe3)(2). From [HIPTN3N]V(THF), the following have been prepared: {[HIPTN3N]VN2}K, [HIPTN3N]V(NH3), [HIPTN3N]V=NH, [HIPTN3N]V=NSiMe3, [HIPTN3N]V=O, [HIPTN3N]V=S, and [HIPTN3N]V(CO). No ammonia is formed from dinitrogen using {[HIPTN3N]VN2}K, [HIPTN3N]V=NH, or [HIPTN3N]V(NH3) as the initial species under conditions that were successful in the analogous [HIPTN3N]Mo system. X-ray structural studies are reported for [HIPTN3N]V(THF) and [HIPTN3N]V(NH3).