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Dihydrogen Binding to Isostructural S = 1/2 and S = 0 Cobalt Complexes

Suess, Daniel L. M. and Tsay, Charlene and Peters, Jonas C. (2012) Dihydrogen Binding to Isostructural S = 1/2 and S = 0 Cobalt Complexes. Journal of the American Chemical Society, 134 (34). pp. 14158-14164. ISSN 0002-7863. doi:10.1021/ja305248f.

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Two isostructural, nonclassical Co(H_2) complexes are prepared from their Co(N_2) precursors using tris(phosphino)silyl and tris(phosphino)borane ancillary ligands. Comproportionation of CoBr_2 and Co metal in the presence of TPB (tris-(o-diisopropylphophinophenyl)borane) gives (TPB)CoBr (4). One-electron reduction of 4 triggers N_2 binding to give (TPB)Co(N_2) (2-N_2) which is isostructural to previously reported [SiP_3]Co(N_2) (1-N_2) ([SiP_3] = tris-(o-diisopropylphosphinophenyl)silyl). Both 1-N_2 and 2-N_2 react with 1 atm H_2 to generate thermally stable H_2 complexes 1-H_2 and 2-H_2, respectively. Both complexes are characterized by a suite of spectroscopic techniques in solution and by X-ray crystallography. The H_2 and N_2 ligands in 2-H_2 and 2-N_2 are labile under ambient conditions and the binding equilibria are observable by temperature-dependent UV/vis. A van’t Hoff analysis allows for the ligand binding energetics to be determined (H_2: ΔHº = −12.5(3) kcal mol^(–1) and ΔSº = −26(3) cal K^(–1) mol^(–1); N_2: ΔHº = −13.9(7) kcal mol^(–1) and ΔSº = −32(5) cal K^(–1) mol^(–1)).

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Peters, Jonas C.0000-0002-6610-4414
Additional Information:© 2012 American Chemical Society. Received: May 30, 2012. Publication Date (Web): August 14, 2012. We thank the Gordon and Betty Moore Foundation and the NSF Center for Chemical Innovation on Solar Fuels (CCI Solar, CHE-0802907 and CHE-0947829) for funding. We thank Prof. George Rossman (solid-state Raman studies), Maraia Ener (solution-state Raman studies), and Lawrence Henling (X-ray crystallography) for experimental assistance.
Group:CCI Solar Fuels
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Gordon and Betty Moore FoundationUNSPECIFIED
Issue or Number:34
Record Number:CaltechAUTHORS:20120910-104427509
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Official Citation:Dihydrogen Binding to Isostructural S = 1/2 and S = 0 Cobalt Complexes Daniel L. M. Suess, Charlene Tsay, and Jonas C. Peters Journal of the American Chemical Society 2012 134 (34), 14158-14164
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:33959
Deposited By: Ruth Sustaita
Deposited On:10 Sep 2012 18:08
Last Modified:09 Nov 2021 23:05

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