A molecular dihydrogen moiety within dimeric chlorohydrido(tertiary phosphine)ruthenium complexes

Intramolecular proton transfer from a cation to the associated, structurally characterised, hydride-containing anion [(PPh3)2(H)Ru(μ-H)(μ-Cl)2Ru(H)(PPh 3)2]− to give an η2-H2 complex

“…identical to those of the neutral h 2 -H 2 complex 2, thus demonstrating conversion of 1 into 2 in this solvent (Scheme 1). The 31 P{ 1 H} spectrum of 1 in C 7 D 8 at 20 °C shows two broad resonances at d 71.3 and 46.3, while at 289 °C the spectrum gives an ABCD spin system, the data corresponding exactly to those previously observed for 2; 4,8,9 the 20 °C spectrum also shows a small amount (ca. 5%) of another species associated with an AB pattern (d A 56.8, d B 54.7, 2 J AB 30 Hz) and this possibly results from the presence of 1.…”

“…The 1 H NMR spectrum of 1 in C 7 D 8 at 20 °C shows a single broad resonance in the hydride region at d 212.8, but at 279 °C signals are seen at d 28.7 (br d), 212.6 (br s) and 217.3 (br s), and these data correspond to those for the m-hydride, h 2 -H 2 and terminal hydride, respectively, of 2, as established by the T 1 measurements and exchange-spectra simulations for these protons [similar data are found for the P(C 6 H 4 Me-p) 3 analogue]. 4,8,9 Two other resonances of lower intensity observed at d 214.9 (t, 2 J PH 31.1 Hz) and d 217.7 (br s) could again be attributed to the terminal-and bridging-hydrides of 1. We have been unable to detect the 1 H resonance for the proton of [Hdma] + .…”

“…complex were not established in earlier X-ray crystallographic studies; however, these complexes did not contain a C 2 axis. 4,8,9 For 1 and the molecular (L)(h 2 -H 2 ) complex, 4 the hydride and the h 2 -H 2 ligands were located. Of note, complex 2 has recently been studied by X-ray crystallography using CCD detection with all the hydride and h 2 -H 2 hydrogens now located.…”

“…A key step in the mechanism of the well known hydrogenation catalyst [Ru(H)Cl(PPh 3 ) 3 ] is initial dissociation of a phosphine ligand to generate species containing the 'Ru(PPh 3 ) 2 ' moiety, 8,9 but whether dinuclear species such as the anion of 1, or the h 2 -H 2 complex 2, play any role in the catalysis still remains to be established.…”

The preparation and structure of a dinuclear .eta.2-H2 complex (P-N)(.eta.2-H2)Ru(.mu.-Cl)2(.mu.-H)Ru(H)(PPh3)2, P-N = Fe[.eta.-C5H3(CHMeNMe2){P(iso-Pr)2}-1,2](.eta.-C5H5)

“…The simulated spectra in Figure 211 used the model of a BXYZ spin system exchanging rapidly with an A2XYZ and slowly with a CXYZ, i.e., /x-H exchanging rapidly with tj2-H2 and this system slowly exchanging with Ru(2)-H. In the dinuclear species 1 and 2, exchange is faster and involves all hydrogen ligands. The 7"| values at -60 °C for the exchanging hydrogens, measured at 300 MHz, for 3 in CD2C12 are (ms) *i2-H2 13.8 (3), p-H 182 (6), and Ru-H 251 (5),12 which are in the expected ranges.2'…”