Synthesis using transition metal diatomic molecules. Dirhodium octacarbonyl and diiridium octacarbonyl

Hanlan, L. A.; Ozin, G. A.

doi:10.1021/ja00827a013

Cited by 74 publications

(46 citation statements)

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“…According to our calculations, the Rh complex presents a low barrier for the C 2v Ǟ D 2d transformation (4.7 kcal·mol Ϫ1 ), although this isomerization cannot be experimentally observed due the formation of larger clusters. [15,16,19] The D 2d Ǟ D 3d transformation presents a barrier of about 8.1 kcal·mol Ϫ1 . For the Ir complex, the larger stability of the intermediate D 2d structure and the calculated energy barriers of about 7Ϫ8 kcal·mol Ϫ1 allow us to predict that a fluxional process should be observable.…”

Section: Energy Minima and Transition Statesmentioning

confidence: 99%

“…The successive appearance of the C 2v , D 2d , and D 3d isomers upon warming is consistent with the theoretical finding that the two transition states located allow no direct conversion of the C 2v and D 3d isomers, but requires going through the D 2d intermediate. [a] (a) Argon matrix at 8 K (solid sample); [12] (b) Hexane solution at 77 K; [12] (c) Paraffin hydrocarbon solvents at variable temperature; [7,8] (d) KBr disk; [67] (e) Spinning-cell FT-Raman (solid state); [66] (f) Calculated with ADF package and BP functional; [58] (g) Co-condensation reaction with CO at 10Ϫ15 K (solid sample) for rhodium [16] and iridium; [18] (h) Liquid paraffin-heptane at high pressure of CO (430Ϫ490 atm, 243Ϫ293 K); [14,15] (i) Adamantane solution at 77 K. [68] Ϫ [b] The band appears as a doublet.…”

Section: Metal؊metal Stretching Vibrationsmentioning

confidence: 99%

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The [M2(CO)8] Complexes of the Cobalt Group

Aullón

Álvarez

2001

Eur. J. Inorg. Chem.

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A theoretical study of the carbonyl complexes [M 2 (CO) 8 ] of the group 9 metals (M = Co, Rh, Ir) is presented. Three isomers were found for each metal, with the relative stabilities and energies differing from one metal to another, and two transition states corresponding to their interconversion processes were identified. The minima in the potential energy surface have been fully characterized through a vibrational

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Section: Energy Minima and Transition Statesmentioning

confidence: 99%

Section: Metal؊metal Stretching Vibrationsmentioning

confidence: 99%

The [M2(CO)8] Complexes of the Cobalt Group

Aullón

Álvarez

2001

Eur. J. Inorg. Chem.

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“…The richness of this chemistry explains the broad interest in the properties of the family of iridium complexes and clusters [25]. Ozin and coworkers [26][27][28] reported the synthesis of Ir(CO) n (n = 1-4) and Ir 2 (CO) 8 clusters in a matrix. Ir 2 (CO) 8 was reported to transform into the tetra-iridium carbonyl cluster Ir 4 (CO) 12 at $200 K [26,27].…”

Section: Introductionmentioning

confidence: 99%

“…Ozin and coworkers [26][27][28] reported the synthesis of Ir(CO) n (n = 1-4) and Ir 2 (CO) 8 clusters in a matrix. Ir 2 (CO) 8 was reported to transform into the tetra-iridium carbonyl cluster Ir 4 (CO) 12 at $200 K [26,27]. The tetra-iridium cluster framework is one of the simplest structures presenting neighboring metal centers, and numerous tetra-iridium clusters are known.…”

Section: Introductionmentioning

confidence: 99%

Structures, relative energies, and ligand dissociation energies of iridium carbonyl phosphine clusters

Zhang

Katz

Gates

et al. 2015

Computational and Theoretical Chemistry

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a b s t r a c tThere is significant interest in the catalytic properties of substituted iridium carbonyl clusters but little thermodynamic information available characterizing them. The low-energy isomers of Ir x (PH 3 ) y (CO) z (x = 1, 2, 4) were investigated with density functional theory and correlated molecular orbital theory at the coupled cluster CCSD(T) level. The relative energies and ligand dissociation energies were calculated. Differences in relative energies are consequences of both electronic and steric effects of the phosphines and carbonyls. The calculations predict three fundamental structural types for Ir 2 (PH 3 ) y (CO) z : C 2v , C 2 , and D 3d . Ten exchange-correlation functionals were used for the ligand dissociation energy calculations in addition to CCSD(T) for the smaller clusters. The xB97X-D functional gave the most consistent ligand dissociation energies as compared with the CCSD(T) benchmark calculations, and, so it was used to predict the dissociation energies for larger clusters when CCSD(T) calculations were infeasible. The dissociation energies characteristic of Ir 4 (PH 3 ) y (CO) z were in the range of $30 to $60 kcal/mol. Dissociation of a bridging ligand often involved a hydrogen atom transfer from a phosphine to a coordinatively unsaturated iridium atom and a phosphine converting from a bridging site to an equatorial site. The products of such reactions are predicted to have lower relative energies than other isomers.Phosphines act as r-electron donors, and there is a trend of an increase in carbonyl ligand dissociation energies as more phosphines are substituted in the small clusters.

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“…The dinuclear Rh 2 (CO) 8 is also non-isolatable and was first observed under hundreds of bar CO partial pressure [56]. This assignment was then confirmed by Hanlan and Ozin [57]. Experimental in situ FTIR evidence for the existence of HRh(CO) 4 , with bands at 2,070, 2,039 and 2,008 cm À1 under circa 1,600 bar of syngas, was initially reported [58], but this result remained inconclusive due to the extreme overlap of peaks.…”

Section: Homometallic Casementioning

confidence: 70%

The Catalytic Binuclear Elimination Reaction: Importance of Non-linear Kinetic Effects and Increased Synthetic Efficiency

Garland

2015

Topics in Organometallic Chemistry

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In the context of metal-mediated organic synthesis, cooperativity and synergism are rather broad terms which are often used to denote systems where unusual rate or selectivity effects are observed. These effects can be exhibited by monometallic, heterobimetallic and even multimetallic systems. The present contribution looks exclusively at one of the simplest cases, namely, systems possessing simultaneously both mononuclear and dinuclear complexes (hence both monometallic and heterobimetallic are included, but multimetallic systems are excluded). In Sect. 1, a brief introduction to the general area and a working definition for catalytic binuclear elimination reaction (CBER) is provided. In Sect. 2, we step back and classify the broad range of systems under consideration in order to enumerate the host of reaction networks considered, the potential for non-linear kinetic effects and how this relates to concepts of synthetic efficiency. In Sect. 3, we return to specific examples of CBER, how they fit into the overall context of the systems classification and how they can be identified in an unambiguous manner using in situ spectroscopic techniques. Indeed, tests can be constructed which permit the experimentalist to check crucial features and characteristics consistent with CBER. The present contribution focuses on the subarea in which CBER systems exist and hence CBER's scope for organic syntheses.

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Synthesis using transition metal diatomic molecules. Dirhodium octacarbonyl and diiridium octacarbonyl

Cited by 74 publications

References 1 publication

The [M2(CO)8] Complexes of the Cobalt Group

The [M2(CO)8] Complexes of the Cobalt Group

Structures, relative energies, and ligand dissociation energies of iridium carbonyl phosphine clusters

The Catalytic Binuclear Elimination Reaction: Importance of Non-linear Kinetic Effects and Increased Synthetic Efficiency

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