TY - JOUR
T1 - Nickel Bis-Diphosphine Complexes
T2 - Controlling the Binding and Heterolysis of H2
AU - Stolley, Ryan M.
AU - Darmon, Jonathan M.
AU - Das, Parthapratim
AU - Helm, Monte
PY - 2016/9/12
Y1 - 2016/9/12
N2 - Two new Ni(II) complexes, the homoleptic [Ni(8PCy 2NH)2]2+ complex (8PCy 2NH = 3,7-cyclohexyl-1-amino-3,7-diphosphacyclooctane) containing two pendant amines on adjacent ligands, and the heteroleptic [Ni(8PCy 2NH)(dppe)]2+ complex (dppe = bis(diphenylphosphino)ethane) containing only a single pendant amine, have been synthesized, and their electrochemical properties are reported. The [Ni(8PCy 2NH)(dppe)]2+ complex is capable of heterolytically cleaving hydrogen, allowing for the first observation of an endo-protonated nickel hydride related to the [Ni(PR 2NR′ 2)2]2+ family of complexes. The [Ni(8PCy 2NH)(dppe)]2+ complex did not exhibit electrocatalytic H2 oxidation activity; however, [Ni(8PCy 2NH)2]2+ is an active electrocatalyst for H2 oxidation with a maximum turnover frequency (kobs) of 18 s-1 under 1 atm H2 at Ecat/2 = -0.71 V versus the ferrocenium/ferrocene (Cp2Fe+/0) couple. In addition to an analysis of the effect of the number of pendant amines on the rates of electrocatalytic H2 oxidation of compounds related to the [Ni(PR 2NR′ 2)2]2+ family, the effect of the secondary pendant amine on intermolecular deprotonation is discussed.
AB - Two new Ni(II) complexes, the homoleptic [Ni(8PCy 2NH)2]2+ complex (8PCy 2NH = 3,7-cyclohexyl-1-amino-3,7-diphosphacyclooctane) containing two pendant amines on adjacent ligands, and the heteroleptic [Ni(8PCy 2NH)(dppe)]2+ complex (dppe = bis(diphenylphosphino)ethane) containing only a single pendant amine, have been synthesized, and their electrochemical properties are reported. The [Ni(8PCy 2NH)(dppe)]2+ complex is capable of heterolytically cleaving hydrogen, allowing for the first observation of an endo-protonated nickel hydride related to the [Ni(PR 2NR′ 2)2]2+ family of complexes. The [Ni(8PCy 2NH)(dppe)]2+ complex did not exhibit electrocatalytic H2 oxidation activity; however, [Ni(8PCy 2NH)2]2+ is an active electrocatalyst for H2 oxidation with a maximum turnover frequency (kobs) of 18 s-1 under 1 atm H2 at Ecat/2 = -0.71 V versus the ferrocenium/ferrocene (Cp2Fe+/0) couple. In addition to an analysis of the effect of the number of pendant amines on the rates of electrocatalytic H2 oxidation of compounds related to the [Ni(PR 2NR′ 2)2]2+ family, the effect of the secondary pendant amine on intermolecular deprotonation is discussed.
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U2 - 10.1021/acs.organomet.6b00486
DO - 10.1021/acs.organomet.6b00486
M3 - Review article
AN - SCOPUS:84986879748
VL - 35
SP - 2965
EP - 2974
JO - Organometallics
JF - Organometallics
SN - 0276-7333
IS - 17
ER -