178383-65-8Relevant articles and documents
Nitro-substituted benzoates of dimolybdenum: The Mo24+ δ to ligand charge transfer band
Chisholm, Malcolm H.,Huffman, John C.,Iyer, Suri S.,Lynn, Matthew A.
, p. 283 - 293 (2008/10/08)
The preparation and characterization of a series of Mo2(O2CAr′)4 compounds, where Ar′ is a nitrosubstituted phenyl group, are described. The introduction of the NO2 group in the 4-(para) position causes a significant red-shift of a metal-to-ligand charge transfer (MLCT) band such that these compounds are intensely purple in solution: λmax ca. 540 nm with ε ~15 000 M-1 cm-1. The cinnamate derivative (O2CCH=CHPh-4-NO2) shows a further red-shift of this MLCT band while the 3-NO2 (meta) derivatives are only slightly red-shifted compared to the parent benzoate Mo2(O2CPh)4. The cyclic voltammograms for Mo2(O2CR)4, where R = Me, tBu, n-octyl, Ph, C6H4-4-NO2, and C6H4-3-NO2 reveal how substituents on R influence the ease of oxidation from the δ orbital. The structure of Mo2(O2CC6H4-3-NO2) 4 was determined by a single crystal X-ray diffraction study as its pyridine adduct with additional pyridine in the lattice. Crystal data for Mo2(O2CC6H4-3-NO2) 4(py)2·2py at -174°C: a = 10.982(2) A, b = 20.457(4) A, c = 10.615(2) A, α = 93.82(1)°, β = 90.49(1)°, γ = 98.31(1)°, Z = 2, dcalc = 1.65 g cm-3 and space group P1. The nature of the MLCT band is discussed in the light of Fenske-Hall MO calculations on Mo2(O2C6H5)4, Mo2(O2C6H4-4-NO2) 4, Mo2(O2CC6H4-3-NO2) 4, and Mo2(O2C6H3-2-Cl-4-NO 2)4.