Details

Autor(en) / Beteiligte

• Wiedner, Eric S.
• Yang, Jenny Y.
• Chen, Shentan
• Raugei, Simone
• Dougherty, William G.
• Kassel, W. Scott
• Helm, Monte L.
• Bullock, R. Morris
• Rakowski DuBois, M.
• DuBois, Daniel L.

Titel

Stabilization of Nickel Complexes with Ni 0 ···H–N Bonding Interactions Using Sterically Demanding Cyclic Diphosphine Ligands

Ist Teil von

• Organometallics, 2012-01, Vol.31 (1), p.144-156

Ort / Verlag

United States: American Chemical Society

Erscheinungsjahr

2012

Link zum Volltext

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• The series of complexes Ni(PtBu₂NR₂)₂, [Ni(PtBu₂NR₂)₂]BF₄, [HNi(PtBu₂NR₂)₂]BF₄, and [Co(PtBu₂NPh₂)₂]BF₄ (PtBu₂NR₂ = 1,5-dialkyl-3,7-tert-butyl-1,5-diaza-3,7-diphosphacyclooctane; alkyl = phenyl, benzyl) have been synthesized and characterized. Spectroscopic, electrochemical, and X-ray diffraction studies indicate these complexes are stable as a result of the tetrahedral arrangement of the two diphosphine ligands. Electrochemical oxidation of [HNi(PtBu₂NPh₂)₂]BF₄ results in rapid proton transfer from nickel at a rate faster than can be observed on the CV time scale. Double protonation of Ni(PtBu₂NBn₂)₂ forms the endo-endo, endo-exo, and exo-exo isomers of [Ni(PtBu₂NBnHNBn)₂](BF₄)₂, which were found to be more stable toward loss of H₂ than previously observed for similar complexes. The presence of Ni⁰···HN hydrogen bonds at the endo protonation sites of [Ni(PtBu₂NBnHNBn)₂](BF₄)₂ results in significant differences in the Ni(I/0) oxidation potentials of each of the isomers. The differences in E1/2(I/0) values correspond to bond free energies of 7.4 and 3.7 kcal/mol for the first and second Ni⁰···HN hydrogen bonds of the endo-exo and endo-endo isomers, respectively. Computational studies give bond dissociation energies of the Ni⁰···HN bonds that are within 1–2 kcal/mol of the experimentally determined values.