88510-49-0Relevant academic research and scientific papers
Reductive intramolecular hydrogen transfer in a d8 metal hydride promoted by CO addition. An experimental study and its theoretical implications
Cecconi, Franco,Ghilardi, Carlo A.,Innocenti, Paolo,Mealli, Carlo,Midollini, Stefano,Orlandini, Annabella
, p. 922 - 929 (2008/10/08)
The nickel(II) hydride [(np3)NiH]BPh4, np3 = tris(2-(diphenylphosphino)ethyl)amine, reacts in both the solid state and solution with carbon monoxide, under mild conditions, to yield the nickel(0) carbonyl derivative [(Hnp3)NiCO]BPh4. The molecular structure of [(Hnp3)NiCO]BPh4·0.5C4H8O has been established by single-crystal X-ray diffraction methods. The crystals are triclinic, space group P1, with the following cell parameters: a = 18.917 (8), b = 16.341 (7), c = 10.151 (5) A?; α = 94.31 (6), β = 94.27 (6), γ = 96.94 (6)°; Z = 2. The structure has been solved by three-dimensional Patterson and Fourier syntheses and refined by least-squares techniques to final R and Rw factors of 0.073 and 0.073, respectively. The nickel atom is tetrahedrally coordinated by the three phosphorus atoms of the np3 ligand and by the carbonyl group. A hydrogen atom lies collinear with the nickel and the apical nitrogen atom of the np3 ligand. The N-H distance, 1.15 (9) A?, indicates a bonding between these two atoms, but the Ni-H distance of 1.95 (9) A? does not exclude some interaction between the hydrogen and the metal atom. The 1H NMR spectra of [(Hnp3)NiCO]BPh4 are indicative of N-H bonding, whereas the IR data suggest at least a weak residual Ni-H interaction. Molecular orbital studies of the extended Hu?ckel type indicate that the N-H bond is energetically favored over a possible Ni-H bond and that the Ni-H overlap population drops to zero as the hydrogen approaches the nitrogen atom along the threefold axis of the complex. A Ni-H interaction of electrostatic nature may be predicted from calculated atomic charges. Calculations have been also performed to evaluate a possible migration path of the hydrogen atom from one apical position of the trigonal bipyramid in [(np3)NiH]+ to the position where is bonded to nitrogen in the carbonyl derivative.
