Preparation and interconversion of two isomeric iridium trihydrides

Harrod, John F.; YORKE, W.

doi:10.1021/ic50218a039

Cited by 28 publications

(14 citation statements)

References 2 publications

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“…The mechanisms might involve reversible loss of hydrogen to give complex 1, non-classical dihydrogen compounds or intramolecular rearrangement reactions. 18,20,22,27 To the best of our knowledge the rhodium complex mer-[Rh(H) 3 (PEt 3 ) 3 ] (mer-7) represents the first mononuclear rhodium compound bearing trans-hydrides. 28 While classical cis-dihydride complexes are abundant, compounds bearing hydrido ligands in the trans position are less common.…”

Section: Discussionmentioning

confidence: 99%

“…28 While classical cis-dihydride complexes are abundant, compounds bearing hydrido ligands in the trans position are less common. [19][20][21][22] Often they are considered to be the thermodynamically unstable isomers, but are sometimes observed simultaneously in a detectable equilibrium with the cisisomer. [20][21][22] This instability is thought to be the result of the large trans influence of hydrido ligands.…”

Section: Discussionmentioning

confidence: 99%

“…[19][20][21][22] Often they are considered to be the thermodynamically unstable isomers, but are sometimes observed simultaneously in a detectable equilibrium with the cisisomer. [20][21][22] This instability is thought to be the result of the large trans influence of hydrido ligands. 29 Nevertheless, the iridium compound mer-[Ir(H) 3 (PEt 3 ) 3 ] can be prepared in situ from the pentahydride trans-[Ir(H) 5 (PEt 3 ) 2 ].…”

Section: Discussionmentioning

confidence: 99%

“…It displays several broad absorption bands in the region between 1860 and 2035 cm −1 (shoulder at 1924 and 1951 cm −1 ), which we assign as symmetric RhH vibrations of both isomers. [19][20][21][22][23] An additional band at 1608 cm −1 is indicative of the trans-H-Rh-H configuration in mer-7. Deuteration of the hydride sites results in a considerable shift to lower frequencies.…”

Section: Reaction Of [Rhh(pet ) ] (1) With Hydrogenmentioning

confidence: 99%

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Hydrodefluorination of pentafluoropyridine at rhodium using dihydrogen: detection of unusual rhodium hydrido complexes

et al. 2007

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The pentafluoropyridyl complex [Rh(4-C5NF4)(PEt3)3] (3) reacts with H2 to give initially the dihydrido complex cis-mer-[Rh(H)2(4-C5NF4)(PEt3)3] (6). Within a few hours 2,3,5,6-tetrafluoropyridine as well as two rhodium(III) complexes mer-[Rh(H)3(PEt3)3] (mer-) and fac-[Rh(H)3(PEt3)3] (fac-) are formed. A catalytic C-F activation process for the formation of 2,3,5,6-tetrafluoropyridine starting from pentafluoropyridine and dihydrogen using 3 as a catalyst has been developed. Reaction of [RhH(PEt3)3] (1) with hydrogen affords fac-[Rh(H)3(PEt3)3] (fac-7) and mer-[Rh(H)3(PEt3)3] (mer-7) in a ratio of 1 : 7.25 at 193 K. The latter complex represents the first mononuclear rhodium compound bearing trans-hydrides.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Reaction Of [Rhh(pet ) ] (1) With Hydrogenmentioning

confidence: 99%

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Hydrodefluorination of pentafluoropyridine at rhodium using dihydrogen: detection of unusual rhodium hydrido complexes

et al. 2007

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“…The 31P-{1H) spectrum was complex at 24.2 MHz, but first order at 145 MHz; at the stronger magnetic field, the resonance due to P'F, was a wide quartet ['J(P'F) = 1 383 Hz] of triplets ['J(PP') = 213. 5 Hz], and that due to PPh3 appeared as a triplet of narrower quartets [3J(PF) = 35.3 Hz]. The 19F spectrum, which we could only run at 94 MHz, appeared at that frequency as a wide doublet of distorted triplets of doublets.…”

Section: Resultsmentioning

confidence: 95%

Reactions between carbonylhydridotris(triphenylphosphine)iridium(I) and difluorophosphine oxide, sulphide, and selenide: identification of ionic intermediates

Ebsworth¹,

Page²,

Rankin³

1984

J. Chem. Soc., Dalton Trans.

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Carbonylhydridotris(triphenylphosphine)iridium(i) (1) reacts with PF2HY (Y = 0, S, or Se) at 190 K in CH2CI2 to give [lr(CO)H2(PPh3),] [PF2Y] (2;, identified by n.m.r. spectroscopy. When the solutions were allowed to warm above 220 K, PPh3 was liberated and complexes [Ir(CO)H?(P.Ph,),-(P'F,Y)] were formed [Y = Se, (3a) ; S, (3b) ; or 0, (3c) 3. Complexes (3a) and (3b) were initially produced in two isomeric forms, with the PPh, groups mutually cis or mutually trans; the cis isomer slowly isomerised to the trans isomer at room temperature. For complex (3c) (Y = 0) only the trans isomer was detected. The complex [Ir(CO) H( PPh3)2( P' F,)] was formed as a by-product in these reactions, and its n.m.r. parameters are reported. The implications of the formation of ionic intermediates in the reactions of (1) are briefly considered in relation to mechanisms of related reactions that are usually considered to involve initial loss of PPh3 from (1 ).

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Trimeric Iridium(I) and Iridium(III) Complexes with the Tripodal Phosphane cis, cis‐1,3,5‐Tris[(diphenylphosphanyl)methyl]cyclohexane (tdppmcy) as Bridging Ligand

Mayer

Kaska

1995

Chem. Ber.

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The excellent ligating properties of tertiary phosphanes have made them important constituents of compounds used for catalysis"], study of structure-bonding relationships, and spectroscopic studied2]. In this context, polyphosphanes have been developed to improve the stability and to control the stereochemistry and reactivity of transition metal complexe~ [~~~]. Polyphosphanes can act as both chelating and bridging ligands, depending on the design of the backbone. In general, the thermodynamic advantage of the chelate effect favors the formation of five-and six-membered rings as compared to the bridging mode. If the bite angle becomes small the bridging mode is observed as well as four-membered rings. If the ring size becomes larger (>7) the bridging mode is preferredI5I. Although the C, symmetry of the ligands should generate pyramidal metal complexes, the use of the cyclohexane ring as backbone in tripodal phosphane ligands results in different coordination behaviorr6-*]. We report here on the coordination chemistry of the tripodal phosphane ligand cis,cis-l,3,5-tris[(diphenylphosphanyl)methyl]cyclohexane (tdppmcy)[61 (1) which forms trinuclear iridium complexes. Trimeric Iridium Complex 2Treatment of Ir(PPh3),(CO)C1 with the potentially tripodal phosphane ligand cis, cis-1,3,5-tris[(diphenylphosphanyl)methyl]cyclohexane (tdppmcy) (1) in a stoichiometric ratio of 3:2 in hot toluene gives the trinuclear tris(carbony1-chloroiridium) complex 2 in high yield (Scheme 1). The composition of 2 has been established by elemental analysis, mass spectrometry, and molecular mass studies. The molecule consists of two tdppmcy (1) ligands held together by three bridging iridium atoms. Each of the three metal centers is trans-coordinated by two diphenylphosphanyl groups of two different tdppmcy ligands, one chlorine and one carbony1 ligand in a square-planar way. The stereochemistry around the coordination centers is thus the same as in Vaska's complex Ir(PPh3)2(CO)Cl[91. This is nicely demonstrated by their IR spectra. The v(C0) absorption at 1957 cm-' of 2 differs from Vaska's complex by only 7 wave numbers. It is observed at a higher energy (>60 wave numbers) than would be expected if all three phosphane groups of one tdppmcy ligand are connected to the same metal center[*, lol.

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Preparation and interconversion of two isomeric iridium trihydrides

Cited by 28 publications

References 2 publications

Hydrodefluorination of pentafluoropyridine at rhodium using dihydrogen: detection of unusual rhodium hydrido complexes

Hydrodefluorination of pentafluoropyridine at rhodium using dihydrogen: detection of unusual rhodium hydrido complexes

Reactions between carbonylhydridotris(triphenylphosphine)iridium(I) and difluorophosphine oxide, sulphide, and selenide: identification of ionic intermediates

Trimeric Iridium(I) and Iridium(III) Complexes with the Tripodal Phosphane cis, cis‐1,3,5‐Tris[(diphenylphosphanyl)methyl]cyclohexane (tdppmcy) as Bridging Ligand

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