Chlorohydrido[2(1H)-pyridonato-N,O]bis[tris(1-methylethyl)phosphine]iridium(III)

Grotjahn, Douglas B.; Lo, Hung-Yi; Groy, Thomas L.

doi:10.1107/s0108270195003507

Cited by 5 publications

(5 citation statements)

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“…This route is unique, because there are only two previous reports of ketene formation from transition metals and carboxylic acid derivatives (acid chlorides), and in these cases the reactions led to free ketenes, , a net result that one also can obtain in many cases by reaction of an acid chloride with a tertiary amine base leads to ketene complex 2a or 4 , along with at least one other Ir-containing product, pyridinato complex 3 , the structure of which has been determined by X-ray crystallography . The fragmentation of 1 gives access to a variety of iridium−ketene complexes, in which the ketene ligand has either two aryl groups, one aryl and one alkyl group, or, albeit in lower yields, only one aryl or alkyl group .…”

Section: Resultsmentioning

confidence: 99%

First Direct Structural Comparison of Complexes of the Same Metal Fragment to Ketenes in Both C,C- and C,O-Bonding Modes

et al. 2001

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Using a series of Ir(I) and Rh(I) ketene complexes, conclusions about the structure and bonding of complexes of the fundamentally important ketene ligand class are reached. In a unique comparison of X-ray structures of the same metal fragment to ketenes in both the eta(2)-(C,C) and the eta(2)-(C,O) binding mode, the Ir-Cl bond distances in complexes of trans-Cl(Ir)[P(i-Pr)(3)](2) to phenylketene [4, eta(2)-(C,C)] and diphenylketene [2a, eta(2)-(C,O)] are 2.371(3) and 2.285(2) A, respectively. This would be consistent with greater trans influence of a ketene ligand bound to a metal through its C=C bond than one connected by its C=O bond. Back-bonding of Ir(I) and Rh(I) to diphenylketene was assessed using trans-Cl(M)[P(i-Pr)(3)](2)[eta(2)-(C,O)-diphenylketene] (2a and 2d). Most bond lengths and angles are identical, but slightly greater back-bonding by Ir(I) is suggested by the somewhat greater deformation of the ketene C=C=O system [C-C-O angles are 136.6(4) and 138.9(4) in the Ir and Rh cases 2a and 2d, respectively]. Syntheses of new labeled ketenes Ph(2)C=(13)C=O and Ph(2)C=C=(18)O and their Ir(I) and Rh(I) complexes are reported, along with the generation of an Ir(I) complex of PhCH=(13)C=O. The effects of isotopic substitution on infrared absorption data for ketene complexes are presented for the first time. Preliminary normal coordinate mode analysis allowed definitive assignment of absorptions ascribed to the C-O stretching frequencies of coordinated ketenes, which are near the absorptions for aromatic ring systems commonly found as substituents on ketenes. For free diphenylketene and four of its complexes and a phenylketene complex characterized by X-ray diffraction, the magnitude of the (13)C-(13)C coupling between the two ketene carbons is correlated to carbon-carbon bond distance.

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Section: Resultsmentioning

confidence: 99%

First Direct Structural Comparison of Complexes of the Same Metal Fragment to Ketenes in Both C,C- and C,O-Bonding Modes

et al. 2001

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“…1,14 Monometallic complexes of bidentate pyridonates (κ 2 -pyridonates) are rarer. 15,16 The hydroxyl substituent of 2-pyridinols is known to interact with anionic ligands via hydrogen bonding. For example, hydrogen bonding between 2-pyridinol and hydride ligands has been observed by Crabtree and Morris.…”

Section: Introductionmentioning

confidence: 99%

Organoiridium Pyridonates and Their Role in the Dehydrogenation of Alcohols

2010

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New derivatives of 2-hydroxypyridine (2-hpH) and Cp*Ir(III) are described. Under conditions for catalytic dehydrogenation of 1-phenylethanol catalyzed by Cp*IrCl(κ 2 -2-hp) (1), the main species observed are [Cp* 2 Ir 2 H 2 (2-hp)]Cl ([2]Cl) and Cp*IrHCl(κ 1 -2-hpH) (3). Crystallographic analysis confirms that the cation in [2]PF 6 consists of a Cp* 2 Ir 2 (μ-H) x 2þ core complemented by a pyridonate ligand that bridges via O and N centers. Although [2]Cl is catalytically highly active, the related salt [2]PF 6 is not. Addition of chloride sources reactivates [2]PF 6 . Collectively, our experiments indicate that [2]Cl is a resting state that reverts to a more active species, which we propose is 1 itself. In situ NMR observations and PPh 3 trapping experiments show that under catalytically relevant conditions 1 rapidly converts to 3, which can be observed spectroscopically. Compound 3 was independently generated by transfer hydrogenation of 1. In other experiments, 1 was found to ring-open upon treatment with PPh 3 to give Cp*IrCl(κ 1 -2-hp)(PPh 3 ), which in turn was found to react with AgPF 6 to give [Cp*Ir(κ 2 -2-hp)(PPh 3 )]PF 6 . Both PPh 3 derivatives proved catalytically inactive for dehydrogenation. Cp*IrCl(κ 2 -2-hp-6-Me) was also prepared but could not be converted to κ 1 -2-hpH-6-Me derivatives. The complex Cp*IrCl(C 5 H 3 O 2 NH), nominally derived from the conjugate base of 2,6dihydroxypyridine, features the novel ligand η 3 -C 3 H 3 (CO) 2 NH.

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“…Pyridonate, the anionic form of the tautomers of 2‐hydroxypyridine and 2‐pyridone, can behave as a monodentate, a 1,3‐bridging, or a chelating ligand through nitrogen and/or oxygen donors (Scheme ) An attractive feature of this bifunctional donor is its potential to act as a proton‐responsive ligand for the facilitation of proton‐transfer catalysis . The work of Rauchfuss and co‐workers on the dehydrogenation of alcohols catalyzed by [Cp*Ir(κ 2 ‐2‐pyridonate)Cl] is an excellent illustration of the use of this type of ligand in catalysis …”

Section: Introductionmentioning

confidence: 99%

Oxidative Cleavage of Styrenes Catalyzed by a Pd^II Complex of an 8‐Hydroxyquinolinonate Ligand

et al. 2016

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Synthesis and catalytic activity of palladium complexes of 8-(pyridin-2-ylmethoxy)quinolinone (3) were investigated. Complexation of 3 with [Pd(CH 3 CN) 2 Cl 2 ] gave the dimeric palladium complex [{N,N-(3)PdCl} 2 ] (4). The structure of 4 was characterized by 1 H/ 13 C NMR spectroscopy and mass spectrometry, and further confirmed by X-ray crystallography. Complex [a] 5449 4 acts as a catalyst for oxidative cleavage of C=C bonds, and it catalyzes the hydration of styrenes in an anti-Markovnikov Wacker manner to give terminal aldehydes as the initial product, which then undergo C-C cleavage to yield the corresponding benzaldehydes. Systematic studies of this catalysis were performed.Scheme 2. Tautomers of 8-hydroxycarbostyril and ligand 3. Results and Discussion Preparation of Palladium ComplexesScheme 3 outlines the synthetic approach leading to the desired ligand 3. Compound 1 was prepared according to a literature procedure. [9] Starting from 8-hydroxyquinoline (2), oxidation and acetylation followed by basic hydrolysis provided 1 in 65 % yield of isolated product. Nucleophilic substitution of 2-(bromomethyl)pyridine with 1 under basic conditions in acetonitrile gave 3 in 82 % yield, which was characterized by IR and NMR spectroscopy and mass spectrometry. The carbonyl stretching band at 1682 cm -1 in the IR spectrum clearly demonstrates the existence of amido functionality. The 1 H NMR spectrum of 3 in CDCl 3 shows a downfield signal at δ = 10.02 ppm corresponding to C(O)NH. The 13 C NMR chemical shift of the carbonyl carbon atom at δ = 162.6 ppm is in agreement with Scheme 3. Preparation of ligand 3.

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Chlorohydrido[2(1H)-pyridonato-N,O]bis[tris(1-methylethyl)phosphine]iridium(III)

Cited by 5 publications

References 3 publications

First Direct Structural Comparison of Complexes of the Same Metal Fragment to Ketenes in Both C,C- and C,O-Bonding Modes

First Direct Structural Comparison of Complexes of the Same Metal Fragment to Ketenes in Both C,C- and C,O-Bonding Modes

Organoiridium Pyridonates and Their Role in the Dehydrogenation of Alcohols

Oxidative Cleavage of Styrenes Catalyzed by a Pd^II Complex of an 8‐Hydroxyquinolinonate Ligand

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Chlorohydrido[2(1H)-pyridonato-N,O]bis[tris(1-methylethyl)phosphine]iridium(III)

Cited by 5 publications

References 3 publications

First Direct Structural Comparison of Complexes of the Same Metal Fragment to Ketenes in Both C,C- and C,O-Bonding Modes

First Direct Structural Comparison of Complexes of the Same Metal Fragment to Ketenes in Both C,C- and C,O-Bonding Modes

Organoiridium Pyridonates and Their Role in the Dehydrogenation of Alcohols

Oxidative Cleavage of Styrenes Catalyzed by a PdII Complex of an 8‐Hydroxyquinolinonate Ligand

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Oxidative Cleavage of Styrenes Catalyzed by a Pd^II Complex of an 8‐Hydroxyquinolinonate Ligand