26103-38-8Relevant articles and documents
Amine attack on the carbonyl ligands of the protonated dicyclopentadienyl-bridged diruthenium complex [{(η5-C5H3)2(SiMe 2)2}Ru2(CO)4(μ-H)]+
Ovchinnikov, Maxim V.,Guzei, Ilia A.,Angelici, Robert J.
, p. 691 - 696 (2008/10/08)
Complexes [{(η5-C5H3)2(SiMe 2)2}Ru2(CO)4(μ-H)]+ (1H+BF4-, 1D+TfO-), with a protonated Ru-Ru bond, were prepared by protonation of {(η5-C5H3)2(SiMe 2)2}Ru2(CO)4 (1) with HBF4·Et2O or CF3SO3D. The bridging proton in 1H+ is removed only very slowly by amine bases even though it is thermodynamically acidic (pKaAN = 6.5 (±0.2)). This remarkable kinetic inertness of the bridging proton allows amines (NH3, NH2CH3, NH(CH3)2, morpholine, piperidine, pyrrolidine) to react with 1H+ by attacking the CO ligand to give a formamide (HC(=O)NR2) and the CO-substituted product {(η5-C5H3)2(SiMe 2)2}Ru2(CO)3(NHR2) (2). Thus, protonation of the metal-metal bond in 1H+ promotes reactions of the CO ligand that are not possible in the unprotonated 1. A proposed mechanism for these reactions is supported by kinetic studies of the reaction of 1D+TfO- with morpholine in nitromethane at 20.0 °C, as well as by deuterium-labeling experiments. The molecular structure of {(η5-C5H3)2-(SiMe 2)2}Ru2(CO)3(NH2CH 3) (2f), as determined by an X-ray diffraction investigation, is also presented.
