title: Formation of phosphorus-nitrogen bonds by reduction of a titanium phosphine complex under molecular nitrogen.
abstract: The reduction of high oxidation state metal complexes in the presence of molecular nitrogen is one of the most common methods to synthesize a dinitrogen complex. However, the presence of strong reducing agents combined with the poor binding ability of N2 can lead to unanticipated outcomes. For example, the reduction of [NPN]ZrCl2(THF) (where NPN = PhP(CH2SiMe2NPh)2) with KC8 under N2 leads to the formation of the side-on bridged dinuclear dinitrogen complex ([NPN]Zr(THF))2(mu-eta2:eta2-N2) with an N-N bond distance of 1.503(3) A; however, reduction of the corresponding titanium precursor, [NPN]TiCl2, under N2 does not generate a dinitrogen complex, rather the bis(phosphinimide) derivative, ([N(PN)N]Ti)2, is isolated in which the added N2 is incorporated between the titanium and phosphine centers. Performing the reaction under 15N2 results in the 15N label being incorporated in the phosphinimide unit. A suggested mechanism for this process involves an initially formed dinitrogen complex being over reduced to generate a species with bridging nitrides that undergoes nucleophilic attack by the coordinated phosphine ligands and formation of the P=N bond of the phosphinimide.
authors.affiliation: Department of Chemistry, The University of British Columbia, 2036 Main Mall, Vancouver, BC, Canada, V6T 1Z1.
authors.forename: Lara
authors.initials: L
authors.lastname: Morello
authors.forename: Peihua
authors.initials: P
authors.lastname: Yu
authors.forename: Christopher D
authors.initials: CD
authors.lastname: Carmichael
authors.forename: Brian O
authors.initials: BO
authors.lastname: Patrick
authors.forename: Michael D
authors.initials: MD
authors.lastname: Fryzuk
mesh_terms: D018360:Crystallography, X-Ray; D008024:Ligands; D008094:Lithium / Q000737:chemistry; D008958:Models, Molecular; D008968:Molecular Conformation; D009584:Nitrogen / Q000737:chemistry*; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D010084:Oxidation-Reduction; D010720:Phosphines / Q000737:chemistry*; D010758:Phosphorus / Q000737:chemistry*; D012825:Silicon / Q000737:chemistry; D013237:Stereoisomerism; D014025:Titanium / Q000737:chemistry*; D015040:Zirconium / Q000737:chemistry
chemical_list: D008024:Ligands; D009942:Organometallic Compounds; D010720:Phosphines; D010758:Phosphorus; D008094:Lithium; D015040:Zirconium; D014025:Titanium; D009584:Nitrogen; D012825:Silicon