Synthesis of [Ru(II)(Tp)(Cl)(PPh3)(CH3CN)] and its reactions with selected terminal alkynes: Experimental and computational studies

The ruthenium complex [Ru(II)(Tp)(Cl)(PPh3)(CH3CN)] (3) [Tp = hydrotris(pyrazolyl)borate] contains substitutional ligands, acetonitrile and chloride, and serves as a starting material for the synthesis of new ruthenium complexes. We found that water was also involved in reactions and formed the alkenyl ketone compound [Ru(Tp)(PPh3)(C(CH2Ph) = CHC(O)Ph)] (4) and the acyl complex [Ru(Tp)(PPh3)(C(O)CH2(C6H5)F)] (5). We suggest that water could be an impurity in the solvent, methanol. Methanol cannot be purified before a synthesis procedure, and water is more reactive than methanol. In order to have a better understanding on those new ruthenium complexes, the density functional theory (DFT) has been carried out at the PBE/DZVP level on the proposed mechanisms of the selected reactions. For the reactions of compound 3 with methyl propiolate or ethyl propiolate in the presence of methanol, the solvent can be the nucleophile, and a similar observation can be seen if methanol is replaced by ethanol.