Activation of hydrogen on iridium(I) centers in water: Solvent effects, pH effects, and iridium-hydride exchange with D2O

David P. Paterniti; Paul J. Roman; Jim D. Atwood

doi:10.1021/om9702690

Activation of hydrogen on iridium(I) centers in water: Solvent effects, pH effects, and iridium-hydride exchange with D₂O

David P. Paterniti
, Paul J. Roman
, Jim D. Atwood

Chemistry

SUNY Buffalo

Research output: Contribution to journal › Article › peer-review

35 Scopus citations

Abstract

The water-soluble iridium complexes trans-Ir(CO)L₂X (X = Cl, OH; L = PPh₂(m-C₆H₄-SO₃K) (TPPMS), P(m-C₆H₄SO₃Na)₃ (TPPTS)) have been used to extend the range of solvent effect for H₂ activation at an iridium(I) center and to examine the effect of pH changes on the rate of H₂ addition to an organometallic center. Hydrogen adds to the square-planar iridium(I) complexes in H₂O and DMSO to give products analogous to those for trans-Ir-(CO)(Cl)(PPh₃)₂ in organic solvents. The kinetic deuterium isotope effect, k_H/k_D = 1 1 (L = TPPMS) and 1.2 (L = TPPTS), for addition of H₂ to trans-Ir(CO)(Cl)L₂ in water is the same as that observed for trans-Ir(CO)(Cl)(PPh₃)₂ in toluene and indicates a common mechanism. More polar solvents accelerate the rate of H₂ addition to trans-Ir(CO)(Cl)L₂, indicating polarity in the transition state. Increasing the pH causes a decrease in the rate of H₂ addition for trans-Ir(CO)(Cl)(TPPMS)₂ and trans-Ir(CO)(Cl)(TPPTS)₂ in water. This pH effect, coupled with a shift of v_CO to higher frequency in water, is ascribed to protonation/hydrogen bonding to the iridium center. The hydride ligands undergo H/D exchange with D₂O in a process that is quite dependent on the trans ligand.

Original language	English
Pages (from-to)	3371-3376
Number of pages	6
Journal	Organometallics
Volume	16
Issue number	15
DOIs	https://doi.org/10.1021/om9702690
State	Published - Jul 22 1997

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title = "Activation of hydrogen on iridium(I) centers in water: Solvent effects, pH effects, and iridium-hydride exchange with D2O",

abstract = "The water-soluble iridium complexes trans-Ir(CO)L2X (X = Cl, OH; L = PPh2(m-C6H4-SO3K) (TPPMS), P(m-C6H4SO3Na)3 (TPPTS)) have been used to extend the range of solvent effect for H2 activation at an iridium(I) center and to examine the effect of pH changes on the rate of H2 addition to an organometallic center. Hydrogen adds to the square-planar iridium(I) complexes in H2O and DMSO to give products analogous to those for trans-Ir-(CO)(Cl)(PPh3)2 in organic solvents. The kinetic deuterium isotope effect, kH/kD = 1 1 (L = TPPMS) and 1.2 (L = TPPTS), for addition of H2 to trans-Ir(CO)(Cl)L2 in water is the same as that observed for trans-Ir(CO)(Cl)(PPh3)2 in toluene and indicates a common mechanism. More polar solvents accelerate the rate of H2 addition to trans-Ir(CO)(Cl)L2, indicating polarity in the transition state. Increasing the pH causes a decrease in the rate of H2 addition for trans-Ir(CO)(Cl)(TPPMS)2 and trans-Ir(CO)(Cl)(TPPTS)2 in water. This pH effect, coupled with a shift of vCO to higher frequency in water, is ascribed to protonation/hydrogen bonding to the iridium center. The hydride ligands undergo H/D exchange with D2O in a process that is quite dependent on the trans ligand.",

author = "Paterniti, \{David P.\} and Roman, \{Paul J.\} and Atwood, \{Jim D.\}",

year = "1997",

month = jul,

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doi = "10.1021/om9702690",

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T1 - Activation of hydrogen on iridium(I) centers in water

T2 - Solvent effects, pH effects, and iridium-hydride exchange with D2O

AU - Paterniti, David P.

AU - Roman, Paul J.

AU - Atwood, Jim D.

PY - 1997/7/22

Y1 - 1997/7/22

N2 - The water-soluble iridium complexes trans-Ir(CO)L2X (X = Cl, OH; L = PPh2(m-C6H4-SO3K) (TPPMS), P(m-C6H4SO3Na)3 (TPPTS)) have been used to extend the range of solvent effect for H2 activation at an iridium(I) center and to examine the effect of pH changes on the rate of H2 addition to an organometallic center. Hydrogen adds to the square-planar iridium(I) complexes in H2O and DMSO to give products analogous to those for trans-Ir-(CO)(Cl)(PPh3)2 in organic solvents. The kinetic deuterium isotope effect, kH/kD = 1 1 (L = TPPMS) and 1.2 (L = TPPTS), for addition of H2 to trans-Ir(CO)(Cl)L2 in water is the same as that observed for trans-Ir(CO)(Cl)(PPh3)2 in toluene and indicates a common mechanism. More polar solvents accelerate the rate of H2 addition to trans-Ir(CO)(Cl)L2, indicating polarity in the transition state. Increasing the pH causes a decrease in the rate of H2 addition for trans-Ir(CO)(Cl)(TPPMS)2 and trans-Ir(CO)(Cl)(TPPTS)2 in water. This pH effect, coupled with a shift of vCO to higher frequency in water, is ascribed to protonation/hydrogen bonding to the iridium center. The hydride ligands undergo H/D exchange with D2O in a process that is quite dependent on the trans ligand.

AB - The water-soluble iridium complexes trans-Ir(CO)L2X (X = Cl, OH; L = PPh2(m-C6H4-SO3K) (TPPMS), P(m-C6H4SO3Na)3 (TPPTS)) have been used to extend the range of solvent effect for H2 activation at an iridium(I) center and to examine the effect of pH changes on the rate of H2 addition to an organometallic center. Hydrogen adds to the square-planar iridium(I) complexes in H2O and DMSO to give products analogous to those for trans-Ir-(CO)(Cl)(PPh3)2 in organic solvents. The kinetic deuterium isotope effect, kH/kD = 1 1 (L = TPPMS) and 1.2 (L = TPPTS), for addition of H2 to trans-Ir(CO)(Cl)L2 in water is the same as that observed for trans-Ir(CO)(Cl)(PPh3)2 in toluene and indicates a common mechanism. More polar solvents accelerate the rate of H2 addition to trans-Ir(CO)(Cl)L2, indicating polarity in the transition state. Increasing the pH causes a decrease in the rate of H2 addition for trans-Ir(CO)(Cl)(TPPMS)2 and trans-Ir(CO)(Cl)(TPPTS)2 in water. This pH effect, coupled with a shift of vCO to higher frequency in water, is ascribed to protonation/hydrogen bonding to the iridium center. The hydride ligands undergo H/D exchange with D2O in a process that is quite dependent on the trans ligand.

UR - https://www.scopus.com/pages/publications/0000209471

U2 - 10.1021/om9702690

DO - 10.1021/om9702690

M3 - Article

AN - SCOPUS:0000209471

SN - 0276-7333

VL - 16

SP - 3371

EP - 3376

JO - Organometallics

JF - Organometallics

IS - 15

ER -

Activation of hydrogen on iridium(I) centers in water: Solvent effects, pH effects, and iridium-hydride exchange with D₂O

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