Charles Casey | University of Wisconsin-Madison (original) (raw)
Papers by Charles Casey
Inorganic Chemistry, 1992
Protonation of K[C[sub 5]H[sub 5](CO)[sub 2]ReH] with CF[sub 3]CO[sub 2]H at [minus]78[degrees]C ... more Protonation of K[C[sub 5]H[sub 5](CO)[sub 2]ReH] with CF[sub 3]CO[sub 2]H at [minus]78[degrees]C produced a 65:35 mixture of cis-C[sub 5]H[sub 5](CO)[sub 2]ReH[sub 2] (cis-1) and trans-C[sub 5]H[sub 5](CO)[sub 2]ReH[sub 2] (trans-1). At 24[degrees]C, this mixture equilibrated to a 2:98 cis-1:trans-1 mixture. Reaction of C[sub 5]H[sub 5](CO)[sub 2]Re([mu]-H)Pt(H)(PPh[sub 3])[sub 2] (3-Ph) with diphenylacetylene at [minus]9[degrees]C initially produced an 84:16 cis-1:trans-1 mixture. Photolysis
Different catalyst resting states for the hydrogenation of aldehydes and ketones by a hydroxycycl... more Different catalyst resting states for the hydrogenation of aldehydes and ketones by a hydroxycyclopentadienyl iron hydride Ligand metal bifunctional catalysts are efficient catalysts for the hydrogenation of polar multiple bonds. Recently we have reported that a hydroxycyclopentadienyl iron hydride complex, closely related to the active reducing agent in the Shvo ruthenium catalyst system, is an efficient catalyst for the selective hydrogenation of aldehydes and ketones at room temperature under low hydrogen pressure. We also showed that the cyclopentadienyl iron hydride is the catalyst resting state in the reduction of ketones. However, we were not able to conclusively determine the catalyst resting state in the hydrogenation of aldehydes. Here we report data showing that the resting state for the hydrogenation of aldehydes is different, a cyclopentadienone iron alcohol complex.
![Research paper thumbnail of Hydrogen Elimination from a Hydroxycyclopentadienyl Ruthenium(II) Hydride: Study of Hydrogen Activation in a Ligand−Metal Bifunctional Hydrogenation Catalyst [J. Am. Chem. Soc. 2005, 127, 3100−3109]](https://attachments.academia-assets.com/43369940/thumbnails/1.jpg)
](Journal of the American Chemical Society
At high temperatures in toluene, [2,5-Ph2-3,4-Tol2(η 5 -C4COH)]Ru(CO)2H (3) undergoes hydrogen el... more At high temperatures in toluene, [2,5-Ph2-3,4-Tol2(η 5 -C4COH)]Ru(CO)2H (3) undergoes hydrogen elimination in the presence of PPh3 to produce the ruthenium phosphine complex [2,5-Ph2-3,4-Tol2-(η 4 -C4CO)]Ru(PPh3)(CO)2 (6). In the absence of alcohols, the lack of RuH/OD exchange, a rate law first order in Ru and zero order in phosphine, and kinetic deuterium isotope effects all point to a mechanism involving irreversible formation of a transient dihydrogen ruthenium complex B, loss of H 2 to give unsaturated ruthenium complex A, and trapping by PPh3 to give 6. DFT calculations showed that a mechanism involving direct transfer of a hydrogen from the CpOH group to form B had too high a barrier to be considered. DFT calculations also indicated that an alcohol or the CpOH group of 3 could provide a low energy pathway for formation of B. PGSE NMR measurements established that 3 is a hydrogen-bonded dimer in toluene, and the first-order kinetics indicate that two molecules of 3 are also involved in the transition state for hydrogen transfer to form B, which is the rate-limiting step. In the presence of ethanol, hydrogen loss from 3 is accelerated and RuD/OH exchange occurs 250 times faster than in its absence. Calculations indicate that the transition state for dihydrogen complex formation involves an ethanol bridge between the acidic CpOH and hydridic RuH of 3; the alcohol facilitates proton transfer and accelerates the reversible formation of dihydrogen complex B. In the presence of EtOH, the rate-limiting step shifts to the loss of hydrogen from B.
Canadian Journal of Chemistry
The tolyl analogue of Shvo's hydroxycyclopentadienyl ruthenium hydride (4) efficiently transf... more The tolyl analogue of Shvo's hydroxycyclopentadienyl ruthenium hydride (4) efficiently transfers a hydride and proton to benzaldehyde or acetophenone to produce an alcohol. This reduction can be performed in toluene, methylene chloride, and THF. Reduction of benzaldehyde in toluene and methylene chloride occurs approximately 300 times faster than in THF at 0 °C. Reduction of acetophenone occurs between 75 and 150 times slower than benzaldehyde at 0 °C in each respective solvent. Despite the differences in rate, mechanistic studies have provided evidence for a similar concerted transfer of acidic and hydridic hydrogens in each solvent. Addition of water to THF led to further rate decrease coupled with an increase in the OH/D kinetic isotope effect and a decrease in the RuH/D kinetic isotope effect. Addition of excess alcohol to toluene or methylene chloride results in the significant retardation of the rate of reduction. The slower rate in THF and in the presence of alcohol is at...
Journal of the Chemical Society, Chemical Communications, 1975
ABSTRACT
Inorganica Chimica Acta, 2002
Protonation of η2-enyne rhenium complex C5Me5(CO)2Re(η2-3,4-trans-PhCCCHCHPh) (24) occurred at ... more Protonation of η2-enyne rhenium complex C5Me5(CO)2Re(η2-3,4-trans-PhCCCHCHPh) (24) occurred at the coordinated alkyne to produce 1-metallacyclopropene complex C5Me5(CO)2Re[η2-trans-(PhHCCH)CCHPh]+BF4− (26), instead of protonation at the non-coordinated alkene to produce an η3-propargyl complex. Protonation of the alkene coordinated η2-enyne rhenium complex C5Me5(CO)2Re(η2-1,2-cis-PhHCCHCCPh] (25) occurred at the non-coordinated alkyne to produce exo-alkylidene η3-allyl complex C5Me5(CO)2Re(η3-exo,anti-CHPhCHCCHPh)+BF4− (27), instead of protonation at the coordinated alkene to
Inorganica Chimica Acta, 1997
Protonation of (Ph3P)2Pt[η2-HCCC(CH3)CH2] (2a) with excess HBF4·Et2O produced the π-allyl compl... more Protonation of (Ph3P)2Pt[η2-HCCC(CH3)CH2] (2a) with excess HBF4·Et2O produced the π-allyl complex (Ph3P)2Pt[η3-H2CCC(CH3)CH2+BF4− (3a-BF4) instead of a π-propargyl complex. Reaction of excess CF3CO2H with 2a initially produced the analogous π-allyl complex 3a-CF3CO2 which then added CF3CO2H across the vinylidene unit of 3a-CF3CO2 to give the π-allyl complex (Ph3P)2Pt[η3-CH3C(CF3CO2)C(CH3)CH2]+CF3CO2−. Protonation of the platinum diyne complex [(p-CH3C6H4)3P]2Pt(η2-CH3CCCCCH3) (7b) with HBF4·Et2O at −73°C initially
Organometallics, 2009
PMe(3) adds selectively to the central carbon of the η(3)- propargyl complex [C(5)Me(5)(CO)(2)Re(... more PMe(3) adds selectively to the central carbon of the η(3)- propargyl complex [C(5)Me(5)(CO)(2)Re(η(3)-CH(2)C≡CCMe(3))][BF(4)] (1-t-Bu) to form the metallacyclobutene [C(5)Me(5)(CO)(2)Re(CH(2)C(PMe(3))=CCMe(3))][BF(4)] (7). The rate of rearrangement of the metallacyclobutene 7 to η(2)-alkyne complex [C(5)Me(5)(CO)(2)Re(η(2)-Me(3)PCH(2)C≡CCMe(3))][BF(4)] (8) is is independent of phosphine concentration, consistent with a dissociative mechanism proceeding via η(3)-propargyl complex 1-t-Bu. The rate of this rearrangement is 480 times slower than the rate of exchange of PMe(3) with the labeled metallacyclobutene 7-d(9). This rate ratio provides an indirect measurement of the regioselectivity for addition of PMe(3) to the central carbon of η(3)-propargyl complex 1-t-Bu to give 7 compared to addition to a terminal carbon to give 8. The addition of PPh(3) to 1-t-Bu gives the metallacyclobutene [C(5)Me(5)(CO)(2)Re(CH(2)C(PPh(3))=CCMe(3))][BF(4)] (11). Low temperature (1)H NMR spectra provide...
Journal of The American Chemical Society, 2006
The stereochemistry of hydrogen transfer from [2,5-Ph2-3,4-Tol2(η 5 -C4COD)]Ru(CO)2D to N-aryl im... more The stereochemistry of hydrogen transfer from [2,5-Ph2-3,4-Tol2(η 5 -C4COD)]Ru(CO)2D to N-aryl imines to give amine complexes was shown to be mostly trans stereospecific. Stereospecific hydrogen transfer is proposed to generate an amine and a coordinatively unsaturated ruthenium intermediate in close proximity. Coordination of the amine is proposed to occur faster than lone pair inversion of the amine. In contrast, hydrogen transfer to N-alkyl imines is stereorandom. It is proposed that stereochemistry is lost in part due to the reversibility of the hydrogen transfer being faster than amine coordination.
Journal of The American Chemical Society, 1979
Page 1. 7282 Journal of the American Chemical Society 1 101:24 1 NoEember 21, 1979 Reactions of (... more Page 1. 7282 Journal of the American Chemical Society 1 101:24 1 NoEember 21, 1979 Reactions of (CO)SWCHC~HS with Alkenes Charles P. Casey,* Stanley W. Polichnowski,* Alan J. Shusterman, and Carol R. Jones Contribution ...
Journal of Organic Chemistry, 2003
The isotope effects in the reaction of [p-(Me2CH)C6H4Me]Ru(NHCHPhCHPhNSO2C6H4-p-CH3) (1) with iso... more The isotope effects in the reaction of [p-(Me2CH)C6H4Me]Ru(NHCHPhCHPhNSO2C6H4-p-CH3) (1) with isopropyl alcohol were 1.79 for transfer of hydrogen from OH to N and 2.86 for transfer from CH to Ru. The isotope effect for transfer of deuterium from doubly labeled material (kCHOH/kCDOD = 4.88) was within experimental error of the product of the two individual isotope effects. These isotope effects provide convincing evidence for a mechanism involving concurrent transfer of hydrogen from oxygen to nitrogen and from carbon to ruthenium.
Journal of The American Chemical Society, 1971
... SOC., 716 (1955). 95 (1965). C. Bjorklund and M. Nilsson, ibid., 675 (1966). translator, Cons... more ... SOC., 716 (1955). 95 (1965). C. Bjorklund and M. Nilsson, ibid., 675 (1966). translator, Consultants Bureau, New York, N. Y., 1966. Whitesides, Casey, Krieger J Decomposition of Vinylic Organometallic Compounds Page 2. ...
Journal of The American Chemical Society, 1983
Page 1. J. Am. Chem. SOC. 1983, 105, 665-667 665 b R=C(CH$3 Figure 1. Possible mechanisms for for... more Page 1. J. Am. Chem. SOC. 1983, 105, 665-667 665 b R=C(CH$3 Figure 1. Possible mechanisms for formation of 7a. cloalkyne. The present communication addresses this question in the case of expansion of the four-membered to the five-mem-bered ring. ...
Organometallics, 2006
ABSTRACT The PPh3-substituted hydroxycyclopentadienyl ruthenium hydride [2,5-Ph2-3,4-Tol2(η5-C4CO... more ABSTRACT The PPh3-substituted hydroxycyclopentadienyl ruthenium hydride [2,5-Ph2-3,4-Tol2(η5-C4COH)]Ru(CO)(PPh3)H (1) stoichiometrically reduces aldehydes and ketones in the presence of a pyridine trap to produce alcohols and the ruthenium pyridine complex 5, with a rate law that is dependent only on [aldehyde] and [1]. The observation of deuterium kinetic isotope effects on substitution of the acidic and hydridic protons of 1 are consistent with concerted transfer of hydrogen to aldehydes during reduction. 1 catalytically hydrogenates aldehydes under mild temperature and pressure conditions. While the Shvo catalyst 2 shows little activity under these conditions, it surpasses 1 at elevated temperatures and pressures. 1 shows high chemoselectivity for catalytic hydrogenation of aldehydes over ketones, while 2 is much less selective.
![Research paper thumbnail of The PPh 3 -Substituted Hydroxycyclopentadienyl Ruthenium Hydride [2,5-Ph 2 -3,4-Tol 2 (η 5 -C 4 COH)]Ru(CO)(PPh 3 )H is a More Efficient Catalyst for Hydrogenation of Aldehydes](https://attachments.academia-assets.com/43369943/thumbnails/1.jpg)
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Organometallics, 2012
The bis(trimethylsilyl)-substituted hydroxycyclopentadienyl ruthenium hydride [2,5-(SiMe 3 ) 2 -3... more The bis(trimethylsilyl)-substituted hydroxycyclopentadienyl ruthenium hydride [2,5-(SiMe 3 ) 2 -3,4-(CH 2 OCH 2 )(η 5 -C 4 COH)]Ru(CO) 2 H (10) is an efficient catalyst for hydrogenation of aldehydes and ketones. Because 10 transfers hydrogen rapidly to aldehydes and ketones and because it does not form an inactive bridging hydride during reaction, hydrogenation of aldehydes and ketones can be performed at room temperature under relatively low hydrogen pressure (3 atm); this is a significant improvement compared with previously developed Shvo type catalysts. Kinetic and 2 H NMR spectroscopic studies of the stoichiometric reduction of aldehydes and ketones by 10 established a two-step process for the hydrogen transfer: (1) rapid and reversible hydrogen bond formation between OH of 10 and the oxygen of the aldehyde or ketone, (2) followed by slow transfer of both proton and hydride from 10 to the aldehyde or ketone. The stoichiometric and catalytic activities of complex 10 are compared to those of other Shvo type ruthenium hydrides and related iron hydrides.
Organometallics, 1986
Page 1. Organometallics 1986,5, 1873-1879 1873 Acknowledgment. Thanks are dueto CNR (ROME) for a ... more Page 1. Organometallics 1986,5, 1873-1879 1873 Acknowledgment. Thanks are dueto CNR (ROME) for a financial support to this study. Registry No. Sn(CH3)4, 594-27-4; SnC14, 7646-78-8; Sn(C-H3)3Cl, 1066-45-1; SII(CH ...
Organometallics, 2009
... Koren-Selfridge , Hannah N. Londino , Jessica K. Vellucci , Bryan J. Simmons , Charle... more ... Koren-Selfridge , Hannah N. Londino , Jessica K. Vellucci , Bryan J. Simmons , Charles P. Casey and Timothy B. Clark* . ... Casey, CP ; Strotman, NA ; Beetner, SE ; Johnson, JB ; Priebe, DC ; Vos, TE ; Khodavandi, B. ; Guzei, IA Organometallics 2006, 25, 1230 1235 ...
Organometallics, 1996
... Charles P. Casey,* Curtis J. Czerwinski, and Randy K. Hayashi. ... Instead, the dinuclear met... more ... Charles P. Casey,* Curtis J. Czerwinski, and Randy K. Hayashi. ... Instead, the dinuclear methoxycarbene complex (η 5 -C 5 H 5 )(CO) 2 Re C(OCH 3 )[(η 5 -C 5 H 4 )Re(CO) 3 ] (11) was isolated by thin-layer chromatography as an orange solid in 13% yield. ...
Journal of the American Chemical Society, 1995
The amphiphilic rhenium carbene complex Cp(CO)2-Re=CDCHzCH2CMe3 undergoes stereospecific addition... more The amphiphilic rhenium carbene complex Cp(CO)2-Re=CDCHzCH2CMe3 undergoes stereospecific addition of HCl to produce a single diastereomer of cis-Cp(C0)zClReCHDCHz-CHzCMe3,I but the absolute stereochemistry of the process could not be determined in part because rotation about the Re=C bond is expected to be fast.2 In the course of synthesizing a rotationally restricted rhenium carbene complex having a twocarbon link between the cyclopentadienyl ligand and the carbene carbon atom, we discovered an equilibrium between the hydroxycarbene complex (C0)2Re=C(0H)CH2CH2(q5-CsH4) (1) and the isomeric metal acyl hydride complex trans-
Inorganic Chemistry, 1992
Protonation of K[C[sub 5]H[sub 5](CO)[sub 2]ReH] with CF[sub 3]CO[sub 2]H at [minus]78[degrees]C ... more Protonation of K[C[sub 5]H[sub 5](CO)[sub 2]ReH] with CF[sub 3]CO[sub 2]H at [minus]78[degrees]C produced a 65:35 mixture of cis-C[sub 5]H[sub 5](CO)[sub 2]ReH[sub 2] (cis-1) and trans-C[sub 5]H[sub 5](CO)[sub 2]ReH[sub 2] (trans-1). At 24[degrees]C, this mixture equilibrated to a 2:98 cis-1:trans-1 mixture. Reaction of C[sub 5]H[sub 5](CO)[sub 2]Re([mu]-H)Pt(H)(PPh[sub 3])[sub 2] (3-Ph) with diphenylacetylene at [minus]9[degrees]C initially produced an 84:16 cis-1:trans-1 mixture. Photolysis
Different catalyst resting states for the hydrogenation of aldehydes and ketones by a hydroxycycl... more Different catalyst resting states for the hydrogenation of aldehydes and ketones by a hydroxycyclopentadienyl iron hydride Ligand metal bifunctional catalysts are efficient catalysts for the hydrogenation of polar multiple bonds. Recently we have reported that a hydroxycyclopentadienyl iron hydride complex, closely related to the active reducing agent in the Shvo ruthenium catalyst system, is an efficient catalyst for the selective hydrogenation of aldehydes and ketones at room temperature under low hydrogen pressure. We also showed that the cyclopentadienyl iron hydride is the catalyst resting state in the reduction of ketones. However, we were not able to conclusively determine the catalyst resting state in the hydrogenation of aldehydes. Here we report data showing that the resting state for the hydrogenation of aldehydes is different, a cyclopentadienone iron alcohol complex.
Journal of the American Chemical Society
At high temperatures in toluene, [2,5-Ph2-3,4-Tol2(η 5 -C4COH)]Ru(CO)2H (3) undergoes hydrogen el... more At high temperatures in toluene, [2,5-Ph2-3,4-Tol2(η 5 -C4COH)]Ru(CO)2H (3) undergoes hydrogen elimination in the presence of PPh3 to produce the ruthenium phosphine complex [2,5-Ph2-3,4-Tol2-(η 4 -C4CO)]Ru(PPh3)(CO)2 (6). In the absence of alcohols, the lack of RuH/OD exchange, a rate law first order in Ru and zero order in phosphine, and kinetic deuterium isotope effects all point to a mechanism involving irreversible formation of a transient dihydrogen ruthenium complex B, loss of H 2 to give unsaturated ruthenium complex A, and trapping by PPh3 to give 6. DFT calculations showed that a mechanism involving direct transfer of a hydrogen from the CpOH group to form B had too high a barrier to be considered. DFT calculations also indicated that an alcohol or the CpOH group of 3 could provide a low energy pathway for formation of B. PGSE NMR measurements established that 3 is a hydrogen-bonded dimer in toluene, and the first-order kinetics indicate that two molecules of 3 are also involved in the transition state for hydrogen transfer to form B, which is the rate-limiting step. In the presence of ethanol, hydrogen loss from 3 is accelerated and RuD/OH exchange occurs 250 times faster than in its absence. Calculations indicate that the transition state for dihydrogen complex formation involves an ethanol bridge between the acidic CpOH and hydridic RuH of 3; the alcohol facilitates proton transfer and accelerates the reversible formation of dihydrogen complex B. In the presence of EtOH, the rate-limiting step shifts to the loss of hydrogen from B.
Canadian Journal of Chemistry
The tolyl analogue of Shvo's hydroxycyclopentadienyl ruthenium hydride (4) efficiently transf... more The tolyl analogue of Shvo's hydroxycyclopentadienyl ruthenium hydride (4) efficiently transfers a hydride and proton to benzaldehyde or acetophenone to produce an alcohol. This reduction can be performed in toluene, methylene chloride, and THF. Reduction of benzaldehyde in toluene and methylene chloride occurs approximately 300 times faster than in THF at 0 °C. Reduction of acetophenone occurs between 75 and 150 times slower than benzaldehyde at 0 °C in each respective solvent. Despite the differences in rate, mechanistic studies have provided evidence for a similar concerted transfer of acidic and hydridic hydrogens in each solvent. Addition of water to THF led to further rate decrease coupled with an increase in the OH/D kinetic isotope effect and a decrease in the RuH/D kinetic isotope effect. Addition of excess alcohol to toluene or methylene chloride results in the significant retardation of the rate of reduction. The slower rate in THF and in the presence of alcohol is at...
Journal of the Chemical Society, Chemical Communications, 1975
ABSTRACT
Inorganica Chimica Acta, 2002
Protonation of η2-enyne rhenium complex C5Me5(CO)2Re(η2-3,4-trans-PhCCCHCHPh) (24) occurred at ... more Protonation of η2-enyne rhenium complex C5Me5(CO)2Re(η2-3,4-trans-PhCCCHCHPh) (24) occurred at the coordinated alkyne to produce 1-metallacyclopropene complex C5Me5(CO)2Re[η2-trans-(PhHCCH)CCHPh]+BF4− (26), instead of protonation at the non-coordinated alkene to produce an η3-propargyl complex. Protonation of the alkene coordinated η2-enyne rhenium complex C5Me5(CO)2Re(η2-1,2-cis-PhHCCHCCPh] (25) occurred at the non-coordinated alkyne to produce exo-alkylidene η3-allyl complex C5Me5(CO)2Re(η3-exo,anti-CHPhCHCCHPh)+BF4− (27), instead of protonation at the coordinated alkene to
Inorganica Chimica Acta, 1997
Protonation of (Ph3P)2Pt[η2-HCCC(CH3)CH2] (2a) with excess HBF4·Et2O produced the π-allyl compl... more Protonation of (Ph3P)2Pt[η2-HCCC(CH3)CH2] (2a) with excess HBF4·Et2O produced the π-allyl complex (Ph3P)2Pt[η3-H2CCC(CH3)CH2+BF4− (3a-BF4) instead of a π-propargyl complex. Reaction of excess CF3CO2H with 2a initially produced the analogous π-allyl complex 3a-CF3CO2 which then added CF3CO2H across the vinylidene unit of 3a-CF3CO2 to give the π-allyl complex (Ph3P)2Pt[η3-CH3C(CF3CO2)C(CH3)CH2]+CF3CO2−. Protonation of the platinum diyne complex [(p-CH3C6H4)3P]2Pt(η2-CH3CCCCCH3) (7b) with HBF4·Et2O at −73°C initially
Organometallics, 2009
PMe(3) adds selectively to the central carbon of the η(3)- propargyl complex [C(5)Me(5)(CO)(2)Re(... more PMe(3) adds selectively to the central carbon of the η(3)- propargyl complex [C(5)Me(5)(CO)(2)Re(η(3)-CH(2)C≡CCMe(3))][BF(4)] (1-t-Bu) to form the metallacyclobutene [C(5)Me(5)(CO)(2)Re(CH(2)C(PMe(3))=CCMe(3))][BF(4)] (7). The rate of rearrangement of the metallacyclobutene 7 to η(2)-alkyne complex [C(5)Me(5)(CO)(2)Re(η(2)-Me(3)PCH(2)C≡CCMe(3))][BF(4)] (8) is is independent of phosphine concentration, consistent with a dissociative mechanism proceeding via η(3)-propargyl complex 1-t-Bu. The rate of this rearrangement is 480 times slower than the rate of exchange of PMe(3) with the labeled metallacyclobutene 7-d(9). This rate ratio provides an indirect measurement of the regioselectivity for addition of PMe(3) to the central carbon of η(3)-propargyl complex 1-t-Bu to give 7 compared to addition to a terminal carbon to give 8. The addition of PPh(3) to 1-t-Bu gives the metallacyclobutene [C(5)Me(5)(CO)(2)Re(CH(2)C(PPh(3))=CCMe(3))][BF(4)] (11). Low temperature (1)H NMR spectra provide...
Journal of The American Chemical Society, 2006
The stereochemistry of hydrogen transfer from [2,5-Ph2-3,4-Tol2(η 5 -C4COD)]Ru(CO)2D to N-aryl im... more The stereochemistry of hydrogen transfer from [2,5-Ph2-3,4-Tol2(η 5 -C4COD)]Ru(CO)2D to N-aryl imines to give amine complexes was shown to be mostly trans stereospecific. Stereospecific hydrogen transfer is proposed to generate an amine and a coordinatively unsaturated ruthenium intermediate in close proximity. Coordination of the amine is proposed to occur faster than lone pair inversion of the amine. In contrast, hydrogen transfer to N-alkyl imines is stereorandom. It is proposed that stereochemistry is lost in part due to the reversibility of the hydrogen transfer being faster than amine coordination.
Journal of The American Chemical Society, 1979
Page 1. 7282 Journal of the American Chemical Society 1 101:24 1 NoEember 21, 1979 Reactions of (... more Page 1. 7282 Journal of the American Chemical Society 1 101:24 1 NoEember 21, 1979 Reactions of (CO)SWCHC~HS with Alkenes Charles P. Casey,* Stanley W. Polichnowski,* Alan J. Shusterman, and Carol R. Jones Contribution ...
Journal of Organic Chemistry, 2003
The isotope effects in the reaction of [p-(Me2CH)C6H4Me]Ru(NHCHPhCHPhNSO2C6H4-p-CH3) (1) with iso... more The isotope effects in the reaction of [p-(Me2CH)C6H4Me]Ru(NHCHPhCHPhNSO2C6H4-p-CH3) (1) with isopropyl alcohol were 1.79 for transfer of hydrogen from OH to N and 2.86 for transfer from CH to Ru. The isotope effect for transfer of deuterium from doubly labeled material (kCHOH/kCDOD = 4.88) was within experimental error of the product of the two individual isotope effects. These isotope effects provide convincing evidence for a mechanism involving concurrent transfer of hydrogen from oxygen to nitrogen and from carbon to ruthenium.
Journal of The American Chemical Society, 1971
... SOC., 716 (1955). 95 (1965). C. Bjorklund and M. Nilsson, ibid., 675 (1966). translator, Cons... more ... SOC., 716 (1955). 95 (1965). C. Bjorklund and M. Nilsson, ibid., 675 (1966). translator, Consultants Bureau, New York, N. Y., 1966. Whitesides, Casey, Krieger J Decomposition of Vinylic Organometallic Compounds Page 2. ...
Journal of The American Chemical Society, 1983
Page 1. J. Am. Chem. SOC. 1983, 105, 665-667 665 b R=C(CH$3 Figure 1. Possible mechanisms for for... more Page 1. J. Am. Chem. SOC. 1983, 105, 665-667 665 b R=C(CH$3 Figure 1. Possible mechanisms for formation of 7a. cloalkyne. The present communication addresses this question in the case of expansion of the four-membered to the five-mem-bered ring. ...
Organometallics, 2006
ABSTRACT The PPh3-substituted hydroxycyclopentadienyl ruthenium hydride [2,5-Ph2-3,4-Tol2(η5-C4CO... more ABSTRACT The PPh3-substituted hydroxycyclopentadienyl ruthenium hydride [2,5-Ph2-3,4-Tol2(η5-C4COH)]Ru(CO)(PPh3)H (1) stoichiometrically reduces aldehydes and ketones in the presence of a pyridine trap to produce alcohols and the ruthenium pyridine complex 5, with a rate law that is dependent only on [aldehyde] and [1]. The observation of deuterium kinetic isotope effects on substitution of the acidic and hydridic protons of 1 are consistent with concerted transfer of hydrogen to aldehydes during reduction. 1 catalytically hydrogenates aldehydes under mild temperature and pressure conditions. While the Shvo catalyst 2 shows little activity under these conditions, it surpasses 1 at elevated temperatures and pressures. 1 shows high chemoselectivity for catalytic hydrogenation of aldehydes over ketones, while 2 is much less selective.
Organometallics, 2012
The bis(trimethylsilyl)-substituted hydroxycyclopentadienyl ruthenium hydride [2,5-(SiMe 3 ) 2 -3... more The bis(trimethylsilyl)-substituted hydroxycyclopentadienyl ruthenium hydride [2,5-(SiMe 3 ) 2 -3,4-(CH 2 OCH 2 )(η 5 -C 4 COH)]Ru(CO) 2 H (10) is an efficient catalyst for hydrogenation of aldehydes and ketones. Because 10 transfers hydrogen rapidly to aldehydes and ketones and because it does not form an inactive bridging hydride during reaction, hydrogenation of aldehydes and ketones can be performed at room temperature under relatively low hydrogen pressure (3 atm); this is a significant improvement compared with previously developed Shvo type catalysts. Kinetic and 2 H NMR spectroscopic studies of the stoichiometric reduction of aldehydes and ketones by 10 established a two-step process for the hydrogen transfer: (1) rapid and reversible hydrogen bond formation between OH of 10 and the oxygen of the aldehyde or ketone, (2) followed by slow transfer of both proton and hydride from 10 to the aldehyde or ketone. The stoichiometric and catalytic activities of complex 10 are compared to those of other Shvo type ruthenium hydrides and related iron hydrides.
Organometallics, 1986
Page 1. Organometallics 1986,5, 1873-1879 1873 Acknowledgment. Thanks are dueto CNR (ROME) for a ... more Page 1. Organometallics 1986,5, 1873-1879 1873 Acknowledgment. Thanks are dueto CNR (ROME) for a financial support to this study. Registry No. Sn(CH3)4, 594-27-4; SnC14, 7646-78-8; Sn(C-H3)3Cl, 1066-45-1; SII(CH ...
Organometallics, 2009
... Koren-Selfridge , Hannah N. Londino , Jessica K. Vellucci , Bryan J. Simmons , Charle... more ... Koren-Selfridge , Hannah N. Londino , Jessica K. Vellucci , Bryan J. Simmons , Charles P. Casey and Timothy B. Clark* . ... Casey, CP ; Strotman, NA ; Beetner, SE ; Johnson, JB ; Priebe, DC ; Vos, TE ; Khodavandi, B. ; Guzei, IA Organometallics 2006, 25, 1230 1235 ...
Organometallics, 1996
... Charles P. Casey,* Curtis J. Czerwinski, and Randy K. Hayashi. ... Instead, the dinuclear met... more ... Charles P. Casey,* Curtis J. Czerwinski, and Randy K. Hayashi. ... Instead, the dinuclear methoxycarbene complex (η 5 -C 5 H 5 )(CO) 2 Re C(OCH 3 )[(η 5 -C 5 H 4 )Re(CO) 3 ] (11) was isolated by thin-layer chromatography as an orange solid in 13% yield. ...
Journal of the American Chemical Society, 1995
The amphiphilic rhenium carbene complex Cp(CO)2-Re=CDCHzCH2CMe3 undergoes stereospecific addition... more The amphiphilic rhenium carbene complex Cp(CO)2-Re=CDCHzCH2CMe3 undergoes stereospecific addition of HCl to produce a single diastereomer of cis-Cp(C0)zClReCHDCHz-CHzCMe3,I but the absolute stereochemistry of the process could not be determined in part because rotation about the Re=C bond is expected to be fast.2 In the course of synthesizing a rotationally restricted rhenium carbene complex having a twocarbon link between the cyclopentadienyl ligand and the carbene carbon atom, we discovered an equilibrium between the hydroxycarbene complex (C0)2Re=C(0H)CH2CH2(q5-CsH4) (1) and the isomeric metal acyl hydride complex trans-