111189-75-4Relevant academic research and scientific papers
A bonding-reactivity relationship for Ni(PCy3)2(CO2): A comparative solid-state-solution nuclear magnetic resonance study (31P, 13C) as a diagnostic tool to determine the mode of bonding of CO2 to a metal center
Aresta, Michele,Gobetto, Roberto,Quaranta, Eugenio,Tommasi, Immacolata
, p. 4286 - 4290 (2008/10/08)
31P and 13C nuclear magnetic resonance spectra in the solid state and in solution, at variable temperature, have been used for the first time to determine a direct correlation of the modes of bonding of CO2 in Ni(PCy3)2(CO2) in the two states. In solution, at 173 K, CO2 is η2-CO bonded to nickel and 31P and 13C chemical shifts are almost identical with the value found for the solid complex, while a dynamic process averages, in solution, the two phosphorus atoms (ΔG? = 39.3 kJ mol-1) at room temperature through an intramolecular motion. The modification of the mode of bonding of CO2 to a metal center that occurs when a solid sample is dissolved in a solvent may be relevant to the reactivity of CO2-transition metal complexes, as shown by the reaction of coordinated CO2 with electrophiles (H+, Ag+) and H2. The temperature can play an important role.
Spectroscopic and chemical studies of nickel(II) hydrides
Darensbourg, Marcetta Y.,Ludwig, Maria,Riordan, Charles G.
, p. 1630 - 1634 (2008/10/08)
The trans influence of X ligands on the spectroscopic properties of the Ni-H bond is reported for the series of square-planar nickel hydrides trans-HNi(X)(PCy3)2 (X = Me, Ph, CN, SCN, I, Br, Cl, SPh, S(p-tol), SH, OAc, O2CH, O2CPh, O2CCF3, OPh) prepared by oxidative addition of HX to [Ni(PCy3)2]2N2 or derivatives of subsequent products. The infrared-derived parameter v(Ni-H) shows a similar ligand dependence as the proton chemical shift of the hydride ligand, with more covalently bound ligands such as methyl or phenyl producing lower v(Ni-H) and smaller upfield chemical shifts as compared to those ligands that bind to Ni(II) with more electrostatic character such as anionic O-donor ligands. Comparisons with other ligand influenced, spectroscopic scales are made. Carbon dioxide and iodomethane were used as chemical probes of reactivity at the Ni-X or Ni-H bond. The derivatives with stronger Ni-H bonds (S and O donors) show no reactivity at the hydride while the C-bond derivatives exhibit CO2 insertion at the hydride. The Ni-H functionality is active toward iodomethane in the C-donor derivatives. A mechanism of hydrogen atom abstraction by methyl radicals is consistent with literature precedents as well as the Ni-H bond strengths determined by spectroscopies.
