Abstract
A series of monometallic dihydrogen complexes of the type M(OEP)(L)(H2) (M = Ru, Os; L = THF, *Im) was synthesized and characterized by 1H NMR. The H-H bond length was found to increase when Os was replaced by Ru or when *Im was replaced by THF. The bond distances (as determined by T1) range from 0.92 to 1.18 Å. The first example of a bimetallic bridging dihydrogen complex, Ru2(DPB)(*Im)2(H2), was also prepared. The H2 ligand is simultaneously bound to both Ru-metal centers. High-field 1H NMR experiments (620 MHz) revealed a -7.37 Hz dipolar splitting of the H2 ligand for this complex. Analysis of this splitting suggests that the H2 ligand is bound with the H-H axis perpendicular to the Ru-Ru axis. These complexes were examined as possible catalysts for the oxidation of dihydrogen through prior heterolytic activation of H2. Only Ru(OEP)(THF)(H2) can be conveniently deprotonated. Ru(OEP)(THF)(H2) is also implicated in the Ru-(OEP)(THF)2 catalyzed isotopic exchange between H2 and D2O in THF solution. Each step for this mechanism has been elucidated. We have also achieved catalytic dihydrogen oxidation using [Ru(OEP)]2 adsorbed onto graphite. Two mechanisms for this ruthenium porphyrin catalyzed dihydrogen oxidation are presented and compared.
| Original language | English |
|---|---|
| Pages (from-to) | 5654-5664 |
| Number of pages | 11 |
| Journal | Journal of the American Chemical Society |
| Volume | 114 |
| Issue number | 14 |
| Publication status | Published - 1992 |
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Dihydrogen complexes of metalloporphyrins : Characterization and catalytic hydrogen oxidation activity. / Collman, James P.; Wagenknecht, Paul S.; Hutchison, James E.; Lewis, Nathan S; Lopez, Michel Angel; Guilard, Roger; L'Her, Maurice; Bothner-By, Aksel A.; Mishra, P. K.
In: Journal of the American Chemical Society, Vol. 114, No. 14, 1992, p. 5654-5664.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Dihydrogen complexes of metalloporphyrins
T2 - Characterization and catalytic hydrogen oxidation activity
AU - Collman, James P.
AU - Wagenknecht, Paul S.
AU - Hutchison, James E.
AU - Lewis, Nathan S
AU - Lopez, Michel Angel
AU - Guilard, Roger
AU - L'Her, Maurice
AU - Bothner-By, Aksel A.
AU - Mishra, P. K.
PY - 1992
Y1 - 1992
N2 - A series of monometallic dihydrogen complexes of the type M(OEP)(L)(H2) (M = Ru, Os; L = THF, *Im) was synthesized and characterized by 1H NMR. The H-H bond length was found to increase when Os was replaced by Ru or when *Im was replaced by THF. The bond distances (as determined by T1) range from 0.92 to 1.18 Å. The first example of a bimetallic bridging dihydrogen complex, Ru2(DPB)(*Im)2(H2), was also prepared. The H2 ligand is simultaneously bound to both Ru-metal centers. High-field 1H NMR experiments (620 MHz) revealed a -7.37 Hz dipolar splitting of the H2 ligand for this complex. Analysis of this splitting suggests that the H2 ligand is bound with the H-H axis perpendicular to the Ru-Ru axis. These complexes were examined as possible catalysts for the oxidation of dihydrogen through prior heterolytic activation of H2. Only Ru(OEP)(THF)(H2) can be conveniently deprotonated. Ru(OEP)(THF)(H2) is also implicated in the Ru-(OEP)(THF)2 catalyzed isotopic exchange between H2 and D2O in THF solution. Each step for this mechanism has been elucidated. We have also achieved catalytic dihydrogen oxidation using [Ru(OEP)]2 adsorbed onto graphite. Two mechanisms for this ruthenium porphyrin catalyzed dihydrogen oxidation are presented and compared.
AB - A series of monometallic dihydrogen complexes of the type M(OEP)(L)(H2) (M = Ru, Os; L = THF, *Im) was synthesized and characterized by 1H NMR. The H-H bond length was found to increase when Os was replaced by Ru or when *Im was replaced by THF. The bond distances (as determined by T1) range from 0.92 to 1.18 Å. The first example of a bimetallic bridging dihydrogen complex, Ru2(DPB)(*Im)2(H2), was also prepared. The H2 ligand is simultaneously bound to both Ru-metal centers. High-field 1H NMR experiments (620 MHz) revealed a -7.37 Hz dipolar splitting of the H2 ligand for this complex. Analysis of this splitting suggests that the H2 ligand is bound with the H-H axis perpendicular to the Ru-Ru axis. These complexes were examined as possible catalysts for the oxidation of dihydrogen through prior heterolytic activation of H2. Only Ru(OEP)(THF)(H2) can be conveniently deprotonated. Ru(OEP)(THF)(H2) is also implicated in the Ru-(OEP)(THF)2 catalyzed isotopic exchange between H2 and D2O in THF solution. Each step for this mechanism has been elucidated. We have also achieved catalytic dihydrogen oxidation using [Ru(OEP)]2 adsorbed onto graphite. Two mechanisms for this ruthenium porphyrin catalyzed dihydrogen oxidation are presented and compared.
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M3 - Article
AN - SCOPUS:0000910791
VL - 114
SP - 5654
EP - 5664
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
SN - 0002-7863
IS - 14
ER -