COMPLEX-REACTION PRODUCT OF DIMOLYBDENUM TETRAACETATE WITH AQUEOUS HYDROCHLORIC-ACID - STRUCTURAL CHARACTERIZATION OF THE HYDRIDO-BRIDGED [MO2CL8H]3-ION, THE [MO(O)CL4(H2O)]-ION, AND AN H5O2+ION WITH AN EXCEPTIONALLY SHORT HYDROGEN-BOND

From a solution prepared by dissolving Mo2(O2CCH3)4in 12 M HCI and heating to 70°C in air followed by addition of tetraethylammonium chloride, deep yellow crystals of [(C2H5)4N]3(H5O2)[Mo2Cl8H][MoCl40(H20)] are slowly deposited. This compound was identified and fully characterized by X-ray crystallography. It contains three entities of structural interest. First, the diaquahydrogen ion, H5O2+, occurs here with an O-H-O distance shorter by ca. 0.07 Å than any previously reported in this ion; indeed, at 2.34 (1) Å, it is comparable to the few shortest O-H-O bonds known. Second, the [Mo2Cl8H]3-ion, with a μ-H atom, is here found in an ordered condition and the hydrogen atom has been located and refined in one of the bridging positions; the Mo-H distances are 1.73 Å. Third, a full structural description of the [trans-MoCl4O-(H2O)]- ion is given. The Mo=O distance is 1.66 (1) Å while Mo-OH2is 2.33 (1) Å. This remarkable compound forms or-thorhombic crystals, space group Pnma, with a = 26.785 (7) Å, b = 10.454 (2) Å, c = 16.874 (4) Å, V = 4725 (2) Å,3and Z = 4. Using 1868 reflections having l>3σ(1) the structure was refined to discrepancy indices of R1= 0.046 and R2= 0.064 and a goodness-of-fit index of 1.35. © 1979, American Chemical Society. All rights reserved.