| Abstract
| - Hybrid triamidoamine ligands of the type (HIPTNHCH2CH2)2NCH2CH2NHAr (where Ar ≠ hexaisopropylterphenyl = 3,5-(2,4,6-i-Pr3C6H2)2C6H3) may be employed to yield a variety of species such as [hybrid]MoN, {[hybrid]MoN2}Na, and {[hybrid]Mo(NH3)}+. No ammonia was formed from dinitrogen in an attempted catalytic reduction when Ar = 3,5-Me2C6H3, 3,5-(CF3)2C6H3, or 3,5-(MeO)2C6H3 as a consequence, it is proposed, of base-catalyzed decomposition of intermediate [hybrid]Mo−NNH species to yield [hybrid]MoN2 species and dihydrogen. The X-ray structure of [(HIPTNHCH2CH2)2NCH2CH2N(3,5-Me2C6H3)]MoN2}Na(THF)2 is shown.
- In the Buchwald−Hartwig reaction between HIPTBr (HIPT = 3,5-(2,4,6-i-Pr3C6H2)2C6H3 = hexaisopropylterphenyl)and (H2NCH2CH2)3N, it is possible to obtain a 65% isolated yield of (HIPTNHCH2CH2)2NCH2CH2NH2. A secondcoupling then can be carried out to yield a variety of “hybrid” ligands, (HIPTNHCH2CH2)2NCH2CH2NHAr, where Ar= 3,5-Me2C6H3, 3,5-(CF3)2C6H3, 3,5-(MeO)2C6H3, 3,5-Me2NC5H3, 3,5-Ph2NC5H3, 2,4,6-i-Pr3C6H2, or 2,4,6-Me3C6H2.The hybrid ligands may be attached to Mo to yield [hybrid]MoCl species. From the monochloride species, a varietyof other species such as [hybrid]MoN, {[hybrid]MoN2}Na, and {[hybrid]Mo(NH3)}+ can be prepared. [Hybrid]MoN2species were prepared through oxidation of {[hybrid]MoN2}Na species with ZnCl2, but they could not be isolated.[Hybrid]MoN−NH species could be observed as a consequence of the protonation of {[hybrid]MoN2}- species,but they too could not be isolated as a consequence of a facile decomposition to yield dihydrogen and [hybrid]MoN2 species. Attempts to reduce dinitrogen catalytically led to little or no ammonia being formed from dinitrogen.The fact that no ammonia was formed from dinitrogen in the case of Ar = 3,5-Me2C6H3, 3,5-(CF3)2C6H3, or 3,5-(MeO)2C6H3 could be attributed to a rapid decomposition of intermediate [hybrid]MoN−NH species in the catalyticreaction, a decomposition that was shown in separate studies to be accelerated dramatically by 2,6-lutidine, theconjugate base of the acid employed in the attempted catalytic reduction. X-ray structures of [(HIPTNHCH2CH2)2NCH2CH2N{3,5-(CF3)2C6H3}]MoCl and [(HIPTNHCH2CH2)2NCH2CH2N(3,5-Me2C6H3)]MoN2}Na(THF)2 are reported.
|
