title: Molybdenum triamidoamine complexes that contain hexa-tert-butylterphenyl, hexamethylterphenyl, or p-bromohexaisopropylterphenyl substituents. An examination of some catalyst variations for the catalytic reduction of dinitrogen.
abstract: Three new tetramines, (ArNHCH(2)CH(2))(3)N, have been synthesized in which Ar = 3,5-(2,4,6-t-Bu(3)C(6)H(2))(2)C(6)H(3) (H(3)[HTBTN(3)N]), 3,5-(2,4,6-Me(3)C(6)H(2))(2)C(6)H(3) (H(3)[HMTN(3)N]), or 4-Br-3,5-(2,4,6-i-Pr(3)C(6)H(2))(2)C(6)H(2) (H(3)[pBrHIPTN(3)N]). The diarylated tetramine, [3,5-(2,4,6-t-Bu(3)C(6)H(2))(2)C(6)H(3)NHCH(2)CH(2)](2)NCH(2)CH(2)NH(2), has also been isolated, and the "hybrid" tetramine [3,5-(2,4,6-t-Bu(3)C(6)H(2))(2)C(6)H(3)NHCH(2)CH(2)](2)NCH(2)CH(2)NH(4-t-BuC(6)H(4)) has been prepared from it. Monochloride complexes, [(TerNCH(2)CH(2))(3)N]MoCl, have been prepared, as well as a selection of intermediates that would be expected in a catalytic dinitrogen reduction such as [(TerNCH(2)CH(2))(3)N]Mo[triple bond]N and [[(TerNCH(2)CH(2))(3)N]Mo(NH(3))][BAr'(4)] (Ter = HTBT, HMT, or pBrHIPT and Ar' = 3,5-(CF(3))(2)C(6)H(3))). Intermediates that contain the new terphenyl-substituted ligands are then evaluated for their efficiency for the catalytic reduction of dinitrogen under conditions where analogous [HIPTN(3)N]Mo species give four turnovers to ammonia under "standard" conditions with an efficiency of approximately 65%. Only [pBrHIPTN(3)N]Mo compounds are efficient catalysts for dinitrogen reduction. The reasons are explored and discussed.
authors.affiliation: Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
authors.forename: Vincent
authors.initials: V
authors.lastname: Ritleng
authors.forename: Dmitry V
authors.initials: DV
authors.lastname: Yandulov
authors.forename: Walter W
authors.initials: WW
authors.lastname: Weare
authors.forename: Richard R
authors.initials: RR
authors.lastname: Schrock
authors.forename: Adam S
authors.initials: AS
authors.lastname: Hock
authors.forename: William M
authors.initials: WM
authors.lastname: Davis
mesh_terms: D000641:Ammonia / Q000737:chemistry; D001713:Biphenyl Compounds / Q000138:chemical synthesis* / Q000737:chemistry*; D002384:Catalysis; D018360:Crystallography, X-Ray; D007202:Indicators and Reagents; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008968:Molecular Conformation; D009584:Nitrogen / Q000737:chemistry*; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry*; D010084:Oxidation-Reduction
chemical_list: D001713:Biphenyl Compounds; D007202:Indicators and Reagents; D008024:Ligands; D009942:Organometallic Compounds; D000641:Ammonia; D009584:Nitrogen