- Synthesis of molybdenum and tungsten complexes that contain triamidoamine ligands of the type (C6F5NCH2CH2)3N and activation of dinitrogen by molybdenum
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Three new ligands of the type (ArNHCH2CH2)3N(Ar = 3,5-bis(trifluoromethyl)phenl,2-(trifluomethyl)-phenyl, and pentafluorophenyl) have been prepared. Only Mo and W complexes containing the [(C6F5NCH2CH2)3N] 3- ([N3N]3-) ligand were found to be stable. Stable complexes that have been prepared include Mo[N3N](NMe2), M[N3N]Cl (M = Mo or W), Mo[N3N](OTf) (M = Mo or W), [N3N]M≡N (M = Mo or W), and {[N3N]Mo=NMe}-(Otf). An X-ray study of Mo[N3N]Cl showed it to be a monomeric distorted trigonal bipyramidal species having a pseudo-C3 symmetry (space group P1, a = 11.265(2) ?, b = 11.371(2) ?, c = 21.805(4) ?, α = 82.40(1)°, β = 79.07(1)°, γ = 74.89(1)°, V = 2637.4 ?3, Z = 4, fw = 772.75, ρ(calcd) = 1.946 g/cm3, R = 0.032, Rw = 0.034). Reduction of Mo[N3N](OTf) with 1 equiv of sodium amalgam yields a dinuclear bridging dinitrogen species, [N3N]-Mo(μ-N2)Mo[N3N]. In the presence of 2 equiv of sodium amalgam in ether Mo[N3N](Otf) is reduced to [N3N]-Mo(N2) [Na(ether)x] (1 3N]Mo(μ-N2)Mo[N3N] can be reduced to [N3N]Mo(N2)[NaLx] by sodium amalgam under dinitrogen and the latter can be oxidized to the former by ferrocenium triflate or air. [N3N]Mo(N2)[NaLx] reacts with Mo[N3N](OTf) to give [N3N]Mo(μ-N2)Mo[N3N], with triisopropylsilyl chloride to give [N3N]MoN=NSi(i-Pr)3, and with tributyltin chloride to give [N3N]MoN=NSn(Bu)3. An X-ray study of [N3N]MoN=NSi(i-Pr)3(space group P21/n, a= 13.524-(3) ?, b = 18.016(4) ?, c = 16.248(3) ?, β = 98.74(2)°, V = 3913(1) ?3 = 4, fw = 922.67, ρ(calcd) = 1.566 g/cm3, R = 0.069 Rw = 0.072) showed it to be a trigonal bipyramidal complex containing a slightly bent diazenido ligand (Mo-Nα = 1.788(9) ?, Mo-Nα-Nβ = 171.1(8)°, Nα-Nβ-Si = 154(1)°).
- Kol, Moshe,Schrock, Richard R.,Kempe, Rhett,Davis, William M.
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p. 4382 - 4390
(2007/10/02)
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