Molecular Structure of the Molybdenum Oxo-Diperoxo Compound MoO(O2)2(OPy)(H2O): A Computational and X-ray Study

We have carried out a combined experimental and theoretical study of the molecular structure of the MoO(O2)2(OPy)(H2O) coordination compound using X-ray crystallography and DFT-B3LYP computational method,
respectively. The MoO(O2)2(OPy)(H2O) complex crystallizes in the orthorhombic space group Pmna with Z = 4,
a = 6.9001(9) Å, b = 8.0471(1) Å, c = 16.227(2) Å, V = 901.0(2) Å3, and the X-ray data analysis yields a
bipyramidal-pentagonal coordination polyhedron for the Mo atom. The pyridine N-oxide (OPy) ligand occupies
the equatorial position, with the oxygen atom of this ligand being located in the same plane as the four peroxo
oxygen atoms. The H2O ligand is situated trans to the oxo group, forming intermolecular hydrogen bonds with
peroxo groups belonging to two adjacent complexes. In our theoretical approach these intermolecular interactions
were taken into account by including two methanol molecules which form hydrogen bonds with the water ligand
leading to a good agreement between the calculated and the experimental geometry. Our results suggest that it is
necessary to take into account the presence of these interactions in order to reconcile the theoretical results to the
experimental data, in particular the distance between Mo and the oxygen of water ligand. These results seem to
be a general feature for analogous bis-peroxo complexes that have been reported in the literature.

本课题组对MoO(O2)2(OPy)(H2O)配位化合物的分子结构进行了结合实验与理论的研究，分别采用了X射线晶体学和DFT-B3LYP计算方法。MoO(O2)2(OPy)(H2O)配合物在正交晶系Pmna空间群中结晶，具有Z = 4，a = 6.9001(9) Å，b = 8.0471(1) Å，c = 16.227(2) Å，V = 901.0(2) ų的晶胞参数，X射线数据分析揭示出Mo原子呈现双锥-五边形的配位多面体结构。吡啶N-氧化物(OPy)配体占据赤道位置，其中该配体的氧原子与四个过氧氧原子位于同一平面。水分子(H2O)配体位于羰基对面，与两个相邻复合物中的过氧基团形成分子间氢键。在理论研究中，通过引入两个甲醇分子与水分子配体形成氢键，以考虑这些分子间相互作用，从而使得计算出的几何结构与实验数据相吻合。本研究结果表明，为了使理论结果与实验数据相吻合，特别是Mo与水分子配体氧之间的距离，有必要考虑这些相互作用的实际存在。这些结果似乎对于文献中报道的类似双过氧复合物而言，是一个普遍特征。