Terminal and bridging parent amido 1,5-cyclooctadiene complexes of rhodium and iridium

Inmaculada Mena; E. A. Jaseer; Miguel A. Casado; Pilar García-Orduña; Fernando J. Lahoz; Luis A. Oro

doi:10.1002/chem.201204391

Terminal and bridging parent amido 1,5-cyclooctadiene complexes of rhodium and iridium

Inmaculada Mena, E. A. Jaseer, Miguel A. Casado^*, Pilar García-Orduña, Fernando J. Lahoz, Luis A. Oro

^*Corresponding author for this work

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

27 Scopus citations

Abstract

The ready availability of rare parent amido d⁸ complexes of the type [{M(μ-NH₂)(cod)}₂] (M=Rh (1), Ir (2); cod=1,5-cyclooctadiene) through the direct use of gaseous ammonia has allowed the study of their reactivity. Both complexes 1 and 2 exchanged the di-olefines by carbon monoxide to give the dinuclear tetracarbonyl derivatives [{M(μ-NH₂)(CO)₂}₂] (M=Rh or Ir). The diiridium(I) complex 2 reacted with chloroalkanes such as CH₂Cl ₂ or CHCl₃, giving the diiridium(II) products [(Cl)(cod)Ir(μ-NH₂)₂Ir(cod)(R)] (R=CH₂Cl or CHCl₂) as a result of a two-center oxidative addition and concomitant metal-metal bond formation. However, reaction with ClCH₂CH ₂Cl afforded the symmetrical adduct [{Ir(μ-NH₂)(Cl) (cod)}₂] upon release of ethylene. We found that the rhodium complex 1 exchanged the di-olefines stepwise upon addition of selected phosphanes (PPh₃, PMePh₂, PMe₂Ph) without splitting of the amido bridges, allowing the detection of mixed COD/phosphane dinuclear complexes [(cod)Rh(μ-NH₂)₂Rh(PR₃) ₂], and finally the isolation of the respective tetraphosphanes [{Rh(μ-NH₂)(PR₃)₂}₂]. On the other hand, the iridium complex 2 reacted with PMe₂Ph by splitting the amido bridges and leading to the very rare terminal amido complex [Ir(cod)(NH₂)(PMePh₂)₂]. This compound was found to be very reactive towards traces of water, giving the more stable terminal hydroxo complex [Ir(cod)(OH)(PMePh₂)₂]. The heterocyclic carbene IPr (IPr=1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene) also split the amido bridges in complexes 1 and 2, allowing in the case of iridium to characterize in situ the terminal amido complex [Ir(cod)(IPr)(NH ₂)]. However, when rhodium was involved, the known hydroxo complex [Rh(cod)(IPr)(OH)] was isolated as final product. On the other hand, we tested complexes 1 and 2 as catalysts in the transfer hydrogenation of acetophenone with iPrOH without the use of any base or in the presence of Cs ₂CO₃, finding that the iridium complex 2 is more active than the rhodium analogue 1. Tight connection: The reactivity and relative strength of NH₂ bridges in cyclooctadiene (cod) complexes of Rh and Ir of the type [{M(μ-NH₂)(cod)}₂] have been tested with a variety of donors. In general they are tightly bound to the metals. With the diiridium complex and selected ligands, the formation of terminal [Ir(d ⁸)-NH₂] species were observed (see scheme).

Original language	English
Pages (from-to)	5665-5675
Number of pages	11
Journal	Chemistry - A European Journal
Volume	19
Issue number	18
DOIs	https://doi.org/10.1002/chem.201204391
State	Published - 26 Apr 2013

Keywords

cyclooctadienyl ligands
hydrogen transfer
iridium
parent amido
rhodium

ASJC Scopus subject areas

Catalysis
Organic Chemistry

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10.1002/chem.201204391

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@article{297eea389b0048d4a4ee44e3a7d1afa1,

title = "Terminal and bridging parent amido 1,5-cyclooctadiene complexes of rhodium and iridium",

abstract = "The ready availability of rare parent amido d8 complexes of the type [\{M(μ-NH2)(cod)\}2] (M=Rh (1), Ir (2); cod=1,5-cyclooctadiene) through the direct use of gaseous ammonia has allowed the study of their reactivity. Both complexes 1 and 2 exchanged the di-olefines by carbon monoxide to give the dinuclear tetracarbonyl derivatives [\{M(μ-NH2)(CO)2\}2] (M=Rh or Ir). The diiridium(I) complex 2 reacted with chloroalkanes such as CH2Cl 2 or CHCl3, giving the diiridium(II) products [(Cl)(cod)Ir(μ-NH2)2Ir(cod)(R)] (R=CH2Cl or CHCl2) as a result of a two-center oxidative addition and concomitant metal-metal bond formation. However, reaction with ClCH2CH 2Cl afforded the symmetrical adduct [\{Ir(μ-NH2)(Cl) (cod)\}2] upon release of ethylene. We found that the rhodium complex 1 exchanged the di-olefines stepwise upon addition of selected phosphanes (PPh3, PMePh2, PMe2Ph) without splitting of the amido bridges, allowing the detection of mixed COD/phosphane dinuclear complexes [(cod)Rh(μ-NH2)2Rh(PR3) 2], and finally the isolation of the respective tetraphosphanes [\{Rh(μ-NH2)(PR3)2\}2]. On the other hand, the iridium complex 2 reacted with PMe2Ph by splitting the amido bridges and leading to the very rare terminal amido complex [Ir(cod)(NH2)(PMePh2)2]. This compound was found to be very reactive towards traces of water, giving the more stable terminal hydroxo complex [Ir(cod)(OH)(PMePh2)2]. The heterocyclic carbene IPr (IPr=1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene) also split the amido bridges in complexes 1 and 2, allowing in the case of iridium to characterize in situ the terminal amido complex [Ir(cod)(IPr)(NH 2)]. However, when rhodium was involved, the known hydroxo complex [Rh(cod)(IPr)(OH)] was isolated as final product. On the other hand, we tested complexes 1 and 2 as catalysts in the transfer hydrogenation of acetophenone with iPrOH without the use of any base or in the presence of Cs 2CO3, finding that the iridium complex 2 is more active than the rhodium analogue 1. Tight connection: The reactivity and relative strength of NH2 bridges in cyclooctadiene (cod) complexes of Rh and Ir of the type [\{M(μ-NH2)(cod)\}2] have been tested with a variety of donors. In general they are tightly bound to the metals. With the diiridium complex and selected ligands, the formation of terminal [Ir(d 8)-NH2] species were observed (see scheme).",

keywords = "cyclooctadienyl ligands, hydrogen transfer, iridium, parent amido, rhodium",

author = "Inmaculada Mena and Jaseer, \{E. A.\} and Casado, \{Miguel A.\} and Pilar Garc{\'i}a-Ordu{\~n}a and Lahoz, \{Fernando J.\} and Oro, \{Luis A.\}",

year = "2013",

month = apr,

day = "26",

doi = "10.1002/chem.201204391",

language = "English",

volume = "19",

pages = "5665--5675",

journal = "Chemistry - A European Journal",

issn = "0947-6539",

publisher = "John Wiley and Sons Inc.",

number = "18",

}

TY - JOUR

T1 - Terminal and bridging parent amido 1,5-cyclooctadiene complexes of rhodium and iridium

AU - Mena, Inmaculada

AU - Jaseer, E. A.

AU - Casado, Miguel A.

AU - García-Orduña, Pilar

AU - Lahoz, Fernando J.

AU - Oro, Luis A.

PY - 2013/4/26

Y1 - 2013/4/26

N2 - The ready availability of rare parent amido d8 complexes of the type [{M(μ-NH2)(cod)}2] (M=Rh (1), Ir (2); cod=1,5-cyclooctadiene) through the direct use of gaseous ammonia has allowed the study of their reactivity. Both complexes 1 and 2 exchanged the di-olefines by carbon monoxide to give the dinuclear tetracarbonyl derivatives [{M(μ-NH2)(CO)2}2] (M=Rh or Ir). The diiridium(I) complex 2 reacted with chloroalkanes such as CH2Cl 2 or CHCl3, giving the diiridium(II) products [(Cl)(cod)Ir(μ-NH2)2Ir(cod)(R)] (R=CH2Cl or CHCl2) as a result of a two-center oxidative addition and concomitant metal-metal bond formation. However, reaction with ClCH2CH 2Cl afforded the symmetrical adduct [{Ir(μ-NH2)(Cl) (cod)}2] upon release of ethylene. We found that the rhodium complex 1 exchanged the di-olefines stepwise upon addition of selected phosphanes (PPh3, PMePh2, PMe2Ph) without splitting of the amido bridges, allowing the detection of mixed COD/phosphane dinuclear complexes [(cod)Rh(μ-NH2)2Rh(PR3) 2], and finally the isolation of the respective tetraphosphanes [{Rh(μ-NH2)(PR3)2}2]. On the other hand, the iridium complex 2 reacted with PMe2Ph by splitting the amido bridges and leading to the very rare terminal amido complex [Ir(cod)(NH2)(PMePh2)2]. This compound was found to be very reactive towards traces of water, giving the more stable terminal hydroxo complex [Ir(cod)(OH)(PMePh2)2]. The heterocyclic carbene IPr (IPr=1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene) also split the amido bridges in complexes 1 and 2, allowing in the case of iridium to characterize in situ the terminal amido complex [Ir(cod)(IPr)(NH 2)]. However, when rhodium was involved, the known hydroxo complex [Rh(cod)(IPr)(OH)] was isolated as final product. On the other hand, we tested complexes 1 and 2 as catalysts in the transfer hydrogenation of acetophenone with iPrOH without the use of any base or in the presence of Cs 2CO3, finding that the iridium complex 2 is more active than the rhodium analogue 1. Tight connection: The reactivity and relative strength of NH2 bridges in cyclooctadiene (cod) complexes of Rh and Ir of the type [{M(μ-NH2)(cod)}2] have been tested with a variety of donors. In general they are tightly bound to the metals. With the diiridium complex and selected ligands, the formation of terminal [Ir(d 8)-NH2] species were observed (see scheme).

AB - The ready availability of rare parent amido d8 complexes of the type [{M(μ-NH2)(cod)}2] (M=Rh (1), Ir (2); cod=1,5-cyclooctadiene) through the direct use of gaseous ammonia has allowed the study of their reactivity. Both complexes 1 and 2 exchanged the di-olefines by carbon monoxide to give the dinuclear tetracarbonyl derivatives [{M(μ-NH2)(CO)2}2] (M=Rh or Ir). The diiridium(I) complex 2 reacted with chloroalkanes such as CH2Cl 2 or CHCl3, giving the diiridium(II) products [(Cl)(cod)Ir(μ-NH2)2Ir(cod)(R)] (R=CH2Cl or CHCl2) as a result of a two-center oxidative addition and concomitant metal-metal bond formation. However, reaction with ClCH2CH 2Cl afforded the symmetrical adduct [{Ir(μ-NH2)(Cl) (cod)}2] upon release of ethylene. We found that the rhodium complex 1 exchanged the di-olefines stepwise upon addition of selected phosphanes (PPh3, PMePh2, PMe2Ph) without splitting of the amido bridges, allowing the detection of mixed COD/phosphane dinuclear complexes [(cod)Rh(μ-NH2)2Rh(PR3) 2], and finally the isolation of the respective tetraphosphanes [{Rh(μ-NH2)(PR3)2}2]. On the other hand, the iridium complex 2 reacted with PMe2Ph by splitting the amido bridges and leading to the very rare terminal amido complex [Ir(cod)(NH2)(PMePh2)2]. This compound was found to be very reactive towards traces of water, giving the more stable terminal hydroxo complex [Ir(cod)(OH)(PMePh2)2]. The heterocyclic carbene IPr (IPr=1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene) also split the amido bridges in complexes 1 and 2, allowing in the case of iridium to characterize in situ the terminal amido complex [Ir(cod)(IPr)(NH 2)]. However, when rhodium was involved, the known hydroxo complex [Rh(cod)(IPr)(OH)] was isolated as final product. On the other hand, we tested complexes 1 and 2 as catalysts in the transfer hydrogenation of acetophenone with iPrOH without the use of any base or in the presence of Cs 2CO3, finding that the iridium complex 2 is more active than the rhodium analogue 1. Tight connection: The reactivity and relative strength of NH2 bridges in cyclooctadiene (cod) complexes of Rh and Ir of the type [{M(μ-NH2)(cod)}2] have been tested with a variety of donors. In general they are tightly bound to the metals. With the diiridium complex and selected ligands, the formation of terminal [Ir(d 8)-NH2] species were observed (see scheme).

KW - cyclooctadienyl ligands

KW - hydrogen transfer

KW - iridium

KW - parent amido

KW - rhodium

UR - https://www.scopus.com/pages/publications/84876930367

U2 - 10.1002/chem.201204391

DO - 10.1002/chem.201204391

M3 - Article

AN - SCOPUS:84876930367

SN - 0947-6539

VL - 19

SP - 5665

EP - 5675

JO - Chemistry - A European Journal

JF - Chemistry - A European Journal

IS - 18

ER -

Terminal and bridging parent amido 1,5-cyclooctadiene complexes of rhodium and iridium

Abstract

Keywords

ASJC Scopus subject areas

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