Side-on bound dinitrogen complex of zirconium supported by a P2N2 macrocyclic ligand

Reduction of [P2N2]ZrCl2 (where P2N2 = PhP(CH2SiMe2NSiMe2CH2)(2)PPh) by KC8 under N-2 generates the dinuclear dinitrogen complex ([P2N2]Zr)(2)(mu-eta(2):eta(2)-N-2) and impurities in varying yields depending on the solvent and temperature. The toluene complex [P2N2]Zr(eta(6)-C7H8) along with a dinuclear species with bridging PC6H5 groups is observable. Also observable in the crude reaction mixtures is the mu-oxodiazenido derivative, ([P2N2]Zr)(2)(mu-eta(2):eta(2)-N2H2)(mu-O), due to reaction with trace H2O. This paper reports the full details of the preparation of ([P2N2]Zr)(2)(mu-eta(2):eta(2)-N-2) including an improved method that involves reduction at low temperatures in a tetrahydrofuran solvent. Also reported is a reproducible synthesis of the oxodiazenido complex along with the X-ray structures of the dinitrogen complex and the oxodiazenido derivative.