Drew Simon C, Hill Jason P, Lane Ian, Hanson Graeme R, Gable Robert W, Young Charles G
Centre for Magnetic Resonance and Centre for Metals in Biology, University of Queensland, Queensland 4072, Australia.
Inorg Chem. 2007 Apr 2;46(7):2373-87. doi: 10.1021/ic060585j. Epub 2007 Mar 8.
Reaction of TpMoVSCl2 with a variety of phenols and thiols in the presence of triethylamine produces mononuclear, thiomolybdenyl complexes TpMoVSX2 [Tp* = hydrotris(3,5-dimethylpyrazol-1-yl)borate; X = 2-(ethylthio)phenolate (etp), 2-(n-propyl)phenolate (pp), phenolate; X2 = benzene-1,2-dithiolate (bdt), 4-methylbenzene-1,2-dithiolate (tdt), benzene-1,2-diolate (cat)]. The complexes have been characterized by microanalysis, mass spectrometry, IR, EPR, and UV-visible spectroscopic data, and X-ray crystallography (for the etp, pp, bdt, and cat derivatives). The mononuclear, six-coordinate, distorted-octahedral Mo centers are coordinated by terminal sulfido (MoS = 2.123(1)-2.1368(8) A), tridentate facial Tp*, and monodentate or bidentate O/S-donor ligands. Multifrequency (S-, X-, Q-band) EPR spectra of the complexes and selected molybdenyl analogues were acquired at 130 K and 295 K and yielded a spin Hamiltonian of Cs symmetry or lower, with gzz < gyy < gxx < ge and Az'z' > Ax'x' approximately Ay'y', and a noncoincidence angle in the range of beta = 24-39 degrees . Multifrequency EPR, especially at S-band, was found to be particularly valuable in the unambiguous assignment of the spin Hamiltonian parameters in these low-symmetry complexes. The weaker pi-donor terminal sulfido ligand yields a smaller SOMO-LUMO gap and reduced g-values for the thiomolybdenyl complexes compared with molybdenyl analogues, supporting existing crystallographic and EPR data for an apically coordinated oxo group in the active site of xanthine oxidase.
在三乙胺存在下，TpMoVSCl₂与多种酚类和硫醇反应生成单核硫代钼酰配合物TpMoVSX₂ [Tp* = 氢三(3,5 - 二甲基吡唑 - 1 - 基)硼酸酯；X = 2 - (乙硫基)苯酚盐(etp)、2 - (正丙基)苯酚盐(pp)、苯酚盐；X₂ = 苯 - 1,2 - 二硫醇盐(bdt)、4 - 甲基苯 - 1,2 - 二硫醇盐(tdt)、苯 - 1,2 - 二醇盐(cat)]。这些配合物已通过微量分析、质谱、红外光谱、电子顺磁共振光谱和紫外可见光谱数据以及X射线晶体学（针对etp、pp、bdt和cat衍生物）进行了表征。单核、六配位、畸变八面体的钼中心由末端硫基（MoS = 2.123(1)-2.1368(8) Å）、三齿面式Tp*以及单齿或双齿的O/S供体配体配位。在130 K和295 K下获得了这些配合物及选定钼酰类似物的多频（S -、X -、Q波段）电子顺磁共振光谱，得到了具有Cs对称性或更低对称性的自旋哈密顿量，其中gzz < gyy < gxx < ge且Az'z' > Ax'x' ≈ Ay'y'，非重合角在β = 24 - 39度范围内。发现多频电子顺磁共振，尤其是在S波段，对于明确这些低对称性配合物的自旋哈密顿量参数特别有价值。与钼酰类似物相比，较弱的π供体末端硫基配体使硫代钼酰配合物的SOMO - LUMO能隙更小且g值降低，这支持了黄嘌呤氧化酶活性位点中顶端配位的氧代基团的现有晶体学和电子顺磁共振数据。
