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# Preparation, Spectroscopic Characterization, X-ray Structure, and Theoretical Investigation of Hydride−, Dihydrogen−, and Acetone−OsTp Complexes: A Hydridotris(pyrazolyl)borate−Cyclopentadienyl Comparison

journal contribution

posted on 2020-04-02, 15:50 authored by Ruth Castro-Rodrigo, Miguel A. Esteruelas, Ana M. López, Montserrat Oliván, Enrique OñateComplex OsH

_{3}Cl(P^{i}Pr_{3})_{2}(**1**) reacts with KTp (Tp = hydridotris(pyrazolyl)borate) in tetrahydrofuran at room temperature to give OsH_{3}(κ^{2}-Tp)(P^{i}Pr_{3})_{2}(**2**). In toluene at 80 °C, the κ^{2}-Tp complex**2**is transformed to the κ^{3}-Tp derivative OsH_{3}Tp(P^{i}Pr_{3}) (**3**) in quantitative yield after 7 h. Protonation of**3**with HBF_{4}affords the bis(dihydrogen) compound [OsTp(η^{2}-H_{2})_{2}(P^{i}Pr_{3})]BF_{4}(**4**). In acetone complex**4**releases the coordinated hydrogen molecules in a sequential manner. At room temperature, the dihydrogen-solvate complex [OsTp(η^{2}-H_{2})(κ^{1}-OCMe_{2})(P^{i}Pr_{3})]BF_{4}(**5**) is formed, while at 56 °C the loss of both hydrogen molecules gives rise to the bis-solvento derivative [OsTp(κ^{1}-OCMe_{2})_{2}(P^{i}Pr_{3})]BF_{4}(**6**). Complexes**2**−**6**have been characterized by X-ray diffraction analysis, and DFT calculations support their formulation. The structures of**3**−**5**have been compared with those of their Cp counterparts OsH_{3}Cp(P^{i}Pr_{3}), [OsH_{2}Cp(η^{2}-H_{2})(P^{i}Pr_{3})]BF_{4}, and [OsH_{2}Cp(κ^{1}-OCMe_{2})(P^{i}Pr_{3})]BF_{4}. The results show that the Tp ligand avoids piano stool geometries, while it enforces dispositions allowing N−Os−N angles close to 90° such as octahedron and pentagonal bipyramid.