TY - JOUR
T1 - Detection of an Iridium-Dihydrogen Complex
T2 - A Proposed Intermediate in Ionic Hydrogenation
AU - Goldberg, Jonathan M.
AU - Goldberg, Karen I.
AU - Heinekey, D. Michael
AU - Burgess, Samantha A.
AU - Lao, David B.
AU - Linehan, John C.
N1 - Funding Information:
This work was supported by NSF under the CCI Center for Enabling New Technologies through Catalysis (CENTC) Phase II Renewal, CHE-1205189. S.A.B. and J.C.L. were supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, & Biosciences. Pacific Northwest National Laboratory is operated by Battelle for the U.S. Department of Energy.
Publisher Copyright:
© 2017 American Chemical Society.
PY - 2017/9/13
Y1 - 2017/9/13
N2 - Addition of high pressures of H2 to five-coordinate [(tBu)4(POCOP)Ir(CO)(H)]OTf [(tBu)4(POCOP) = κ3-C6H3-2,6-(OP(tBu)2)2] complexes results in observation of two new iridium-dihydrogen complexes. If the aryl moiety of the POCOP ligand is substituted with an electron withdrawing protonated dimethylamino group at the para position, hydrogen coordination is enhanced. Five-coordinate Ir-H complexes generated by addition of triflic acid to (tBu)4(POCOP)Ir(CO) species show an Ir-H 1H NMR chemical shift dependence on the number of equivalents of acid present. It is proposed that excess triflic acid in solution facilitates triflate dissociation from iridium, resulting in unsaturated five-coordinate Ir-H complexes. The five-coordinate iridium-hydride complexes were found to catalyze H/D exchange between H2 and CD3OD. The existence of the dihydrogen complexes, as well as isotope exchange reactions, provide evidence for proposed ionic hydrogenation intermediates for glycerol deoxygenation.
AB - Addition of high pressures of H2 to five-coordinate [(tBu)4(POCOP)Ir(CO)(H)]OTf [(tBu)4(POCOP) = κ3-C6H3-2,6-(OP(tBu)2)2] complexes results in observation of two new iridium-dihydrogen complexes. If the aryl moiety of the POCOP ligand is substituted with an electron withdrawing protonated dimethylamino group at the para position, hydrogen coordination is enhanced. Five-coordinate Ir-H complexes generated by addition of triflic acid to (tBu)4(POCOP)Ir(CO) species show an Ir-H 1H NMR chemical shift dependence on the number of equivalents of acid present. It is proposed that excess triflic acid in solution facilitates triflate dissociation from iridium, resulting in unsaturated five-coordinate Ir-H complexes. The five-coordinate iridium-hydride complexes were found to catalyze H/D exchange between H2 and CD3OD. The existence of the dihydrogen complexes, as well as isotope exchange reactions, provide evidence for proposed ionic hydrogenation intermediates for glycerol deoxygenation.
UR - http://www.scopus.com/inward/record.url?scp=85029474668&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85029474668&partnerID=8YFLogxK
U2 - 10.1021/jacs.7b06480
DO - 10.1021/jacs.7b06480
M3 - Article
C2 - 28862847
AN - SCOPUS:85029474668
VL - 139
SP - 12638
EP - 12646
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
SN - 0002-7863
IS - 36
ER -