1079337-96-4Relevant academic research and scientific papers
Synthesis and characterisation of [(triphos)Fe(CO)H2] and its protonation to a dihydrogen complex via an unconventional hydrogen-bonded intermediate
Guilera, Gemma,McGrady, G. Sean,Steed, Jonathan W.,Burchell, Richard P. L.,Sirsch, Peter,Deeming, Anthony J.
, p. 1573 - 1581 (2008)
The complex [(triphos)Fe(CO)H2] 1 has been prepared and characterised by 1H and 31P NMR and IR spectroscopies, and by single-crystal X-ray diffraction. Complex 1 is fluxional at ambient temperatures in solution; NMR spectral simulation shows that both a Bailar twist of the triphos ligand and pairwise hydride exchange contribute to this fluxionality, with the latter process apparently more facile. DFT-calculated vibrational frequencies for 1 indicate that both these processes are thermally accessible at ambient temperatures. The X-ray crystal structure of complex 1 shows that the triphos ligand adopts a fac arrangement in a distorted octahedral structure, with the two hydride ligands mutually cis, and a non-linear Fe-C-O moiety. Protonation of complex 1 with hexafluoroisopropanol (HFIP) initially produces a hydrogen-bonded intermediate; reaction proceeds further to give the cationic complex [(triphos)Fe(CO)H(η2-H2)] +2. Complex 2 decomposes above 250 K in solution, but has been characterised by NMR spectroscopy. T1 min and JHD measurements indicate that 2 contains a stretched dihydrogen ligand, with r HH = 1.03 A, in apparent disagreement with DFT calculations that suggest that the equilibrium H-H distance is 0.85 A, indicative of a conventional dihydrogen moiety. However, the very shallow nature of the potential energy surface for the Ru(η2-H2) moiety can account for this difference between experimental and calculated values. The experimental and computed structural and spectroscopic features deduced for 1 and 2 are compared with those of their known ruthenium analogues, and are discussed in the context of other hydride and dihydrogen complexes of the Group 8 metals. The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.
