129238-84-2Relevant articles and documents
Dioxomolybdenum(VI) Complexes of Tripodal Nitrogen-Donor Ligands: Syntheses and Spectroscopic, Structural, and Electrochemical Studies, Including the Generation of EPR-Active Molybdenum(V) Species in Solution
Xiao, Zhiguang,Bruck, Michael A.,Doyle, Colleen,Enemark, John H.,Grittini, Carina,et al.
, p. 5950 - 5962 (1995)
The dioxo-Mo(VI) complexes LMoO2X [L = hydrotris(3,5-dimethylpyrazol-1-yl)borate (L(a)), hydrotris(3-isopropylpyrazol-1-yl)borate (L(b)), hydrotris(3,5-dimethyl-1,2,4-triazol-1-yl)borate (L(c)); X = Cl, Br, NCS, OMe, OEt, OPh, SPr(i), SPh, SCH2Ph] have been synthesized and characterizedby spectroscopic and structural methods. The infrared spectra of the complexes exhibit ν(MoO2) bands at 940-920 and 910-890 cm**-1, and the (1)H NMR spectra are indicative of molecular Cs symmetry in solution. The X-ray crystal structures of three complexes are reported. L(a)MoO2(SPh): monoclinic space group P21/c, a = 18.265(6) ?, b = 8.110(3) ?, c = 18.299(3) ?, β = 117.06(2)°, V = 2414(1) ?**3 with Z = 4. L(b)MoO2(OMe): monoclinic space group C2/c, a = 30.365(4) ?, b = 8.373(1) ?, c = 19.646(2) ?, β = 113.28(1)°, V = 4588(1) ?**3 with Z = 8. L(c)MoO2(SPh): orthorhombic space group P212121, a = 7.9302(13) ?, b = 16.627(2) ?, c = 17.543(2) ?, V = 2313.1(9) ?**3 with Z = 4. The structures were refined by full-matrix least-squares procedures to R values of 0.043, 0.027, and 0.039, respectively. The mononuclear complexes feature facially tridentate N-donor ligands, mutually cis oxo and X ligands, and distorted octahedralgeometries. The alkoxy and thiolate complexes undergo a reversible, one-electron reduction to form the corresponding dioxo-Mo(V) anions [LMo(V)O2X](1-). The requirements for reversible, one-electron electrochemical reduction of dioxo-Mo(VI) complexes appear to be (i) minimal conformational change, restricting substitution trans to the oxo groups, upon reduction and (ii) a steric or electrostatic barrier to the close approach and dinucleation of the reduced species. A number of oxo-hydroxo-Mo(V) complexes of the type LMo(V)O(OH)X were generated by protonation of the anions [LMo(V)O2X](1-). Chemical reduction by Bu(n)4NSH results in the sequential generation of [LMo(V)O2X](1-) and [LMo(V)OSX](1-) anions (except for X = OPh, SPh, and SPr(i), when only [LMo(V)O2X](1-) is formed). The Mo(V) complexes have been characterized by EPR spectroscopy.
Dioxomolybdenum(VI) complexes of the hydrotris(3,5-dimethyl-1-pyrazolyl)borate ligand. Synthesis and oxygen atom transfer reactions
Roberts, Sue A.,Young, Charles G.,Kipke, Cary A.,Cleland Jr.,Yamanouchi, Katsumoto,Carducci, Michael D.,Enemark, John H.
, p. 3650 - 3656 (2008/10/08)
The complexes {HB(Me2pz)3}MoO2X (HB(Me2pz)3- = hydrotris(3,5-dimethyl-1-pyrazolyl)borate; X = F-, Cl-, Br-, NCS-, OPh-, OMe-, SPh-) have been prepared and characterized, and the crystal structure of the X = NCS- complex has been determined. {HB(Me2pz)3}MoO2(NCS) crystallizes in the space group P1, with a = 8.049 (1) ?, b = 8.669 (1) ?, c = 17.397 (2) ?, α = 79.98 (1)°, β = 81.30 (1)°, γ = 78.39 (1)°, and Z = 2; refinement resulted in Rw = 0.056 (3136 reflections with Fo2 > 3σ(Fo2), 273 variable parameters). Three representative complexes (X = Cl-, SPh-, OPh-) react with Ph3P at room temperature to yield Ph3PO and a molybdenum-containing product having a composition dependent upon the solvent used. In DMF, pyridine, or acetonitrile, the Mo(IV) complexes {HB(Me2pz3)}MoOX(solvent) are formed as a result of the oxygen atom transfer reaction and subsequent solvent coordination. In dichloromethane, the ultimate products are the Mo(V) complexes {HB(Me2pz)3}MoOClX. In toluene, binuclear Mo(V) complexes {HB(Me2pz)3}2Mo2O3X 2 form from reaction of the transient {HB(Me2pz)3}MoOX and the starting complex. The identities of two reaction products have been confirmed by crystal structure determinations. {HB(Me2pz)3}MoO(Cl)(NCS) crystallizes in space group P1, with a = 8.093 (1) ?, b = 8.840 (1) ?, c = 17.432 (3) ?, α = 79.30 (1)°, β = 80.66 (I)°, γ = 78.40 (1)°, and Z = 2; refinement resulted in Rw = 0.053 (2864 reflections with Fo2 > 3σ(Fo2), 277 variable parameters). The structure is isomorphous with that of {HB(Me2pz)3}MoO2(NCS). {HB(Me2pz)3}MoO(Cl)(NC5H5) crystallizes in P1, with a = 9.636 (1) ?, b = 14.319 (2) ?, c = 20.802 (3) ?, α = 79.90 (1)°, β = 84.47 (1)°, γ = 77.82 (1)°, and Z = 4; refinement resulted in Rw = 0.071 (6777 reflections with Fo2 > 3σ(Fo2), 589 variable parameters). The oxidation of Ph3P to Ph3PO by Me2SO is catalyzed by {HB(Me2pz)3}MoO2X complexes with X = Cl-, SPh-, and OPh-.
