A new member of the (HRhL2)x cluster class: [(.mu.-H)Rh(1,5-cyclooctadiene)]4

Kulzick, Matthew A.; Price, Robert T.; Muetterties, E. L.; Day, Victor W.

doi:10.1021/om00069a034

Cited by 41 publications

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“…In constructing our hypotheses, we also employed that principle of efficient science of ''go to the literature'' by going back and carefully relooking at the literature of the rhodium congener, [Rh(1,5-COD)(l-H)] 4 . Interestingly, one finds 3 different syntheses [9][10][11] for the Rh 4 -based subnanometer cluster, syntheses which differ in the starting [Rh(1,5-COD)Cl] 2 precursor concentration (30 mM or 60 mM in THF) and in the use of LiBEt 3 H vs NaBEt 3 H at À78°C, 0°C, or room temperature [9][10][11]. This reanalysis of the literature suggests that especially the À78°C component of our synthesis [1] may not be optimum or even necessary, a hypothesis we will return to in testing hypotheses #3 and #6 in what follows.…”

Section: Results and Initial Discussionmentioning

confidence: 99%

The story of a mechanism-based solution to an irreproducible synthesis resulting in an unexpected closed-system requirement for the LiBEt3H-based reduction: The case of the novel subnanometer cluster, [Ir(1,5-COD)(μ-H)]4, and the resulting improved, independently repeatable, reliable synthesis

Laxson

Özkâr

Folkman

et al. 2015

Inorganica Chimica Acta

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Tetra-iridium subnanometer cluster Reproducible syntheses Mechanism and radical-cage chemistry Super hydride reductions Hydrogen formation from super hydride a b s t r a c t Reproducibility is the hallmark of reliable science. Reproducible synthetic procedures are of central importance in the chemical sciences, yet P12% of syntheses submitted to publications that explicitly check procedures before their publication, such as Inorganic Syntheses and Organic Syntheses, are reported as having to be rejected since the submitted synthesis could not be repeated. In the present contribution paper we re-examine our own 2012 synthesis of [Ir(1,5-COD)(l-H)] 4 which, frustratingly, we were unable to reproducible once the first author of the original publication completed his stent in our labs. We detail the approach we took to uncover the problems in the synthesis, a key step in which was constructing a ''paper mechanism'' that led to the key hypothesis of what was going wrong in our attempts to repeat the published synthesis. The results have led to an improved synthesis, one shown to be reproducible by a second researcher working only from the detailed written procedure. Also detailed are the 4 conceptual Steps that were used to find the main problems in the synthesis, as well as the 7 specific alternative hypotheses that were involved and 20 experimental trials which discovered the missing detail in the original synthesis-the previously unknown need to employ a closed reaction system-and which led to the present, further improved synthesis which we demonstrate can be reproduced by an independent researcher with no prior Schlenk-technique experience working from only the written procedure. The hard-won insight of the need for a closed system is likely of broader significance and applicability to analogous syntheses involving metal-reductions by LiBEt 3 H and probably other anionic hydrides. A summary and conclusion section is included, one striving toward assisting the design and reporting of more reproducible syntheses in the chemical sciences.

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Section: Results and Initial Discussionmentioning

confidence: 99%

The story of a mechanism-based solution to an irreproducible synthesis resulting in an unexpected closed-system requirement for the LiBEt3H-based reduction: The case of the novel subnanometer cluster, [Ir(1,5-COD)(μ-H)]4, and the resulting improved, independently repeatable, reliable synthesis

Laxson

Özkâr

Folkman

et al. 2015

Inorganica Chimica Acta

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“…The insertion of a functionalized olefin into a Rh–H bond seemed to be the most promising route (see Scheme ). The corresponding compound, [{Rh(cod)(μ‐H)} 4 ] ( 1 ), is easily accessible by β‐H elimination from the unstable ethyl complex 11. However, the insertion of maleates or fumarates into the Rh–H bond of 1 was not observed, which was most probably due to kinetic reasons 12.…”

Section: Resultsmentioning

confidence: 99%

“…The use of EtMgCl to generate the hydride, however, makes it impossible to add DMFu from the beginning of the reaction. Attempts to first form the Rh ethyl complex11 at low temperatures and then add DMFu before β‐H elimination takes place, resulted in the formation of complex product mixtures. We therefore decided to investigate the reaction of cyclohexenyl complex 3 18 with DMFu and speculated that this type of allyl complex might be in equilibrium with the corresponding 1,3‐cyclohexadiene–rhodium hydride complex (see Scheme , top).…”

Section: Resultsmentioning

confidence: 99%

Synthesis and Reactivity of Ester‐Functionalized 5‐Membered Rh^I‐κ²‐C,O‐Chelates and Their Relevance in Rh(cod)‐Mediated Carbene Polymerization

et al. 2011

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The previous mechanistic studies of the Rh-mediated polymerization of carbenes suggests the involvement of organometallic compounds that have been derived from Rh(diene) species that contain a five-membered chelate ring of the type Rh{κ 2 -C,O-[-CH(COOR)-CH(Pol)-C(OR)=O-]} (Pol = polymer chain), which are characterized by the coordination of the β-ester group of the growing polymer chain to the metal. Herein we present our efforts to characterize the possibly related Rh I (cod){κ 2 -C,O-[-CH(COOR)-CHRЈ-C(OR)=O-]} (cod = 1,5-cyclooctadiene) species. These structures can be generated by means of olefin exchange with an allyl complex and [a] Van'

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“…Studies of electronic and coordinative deficiency in mononuclear complexes suggest that unsaturated transition metal clusters should exhibit unique patterns of chemical behavior with potential applications in catalysis [1][2][3][4][5]. The availability of multiple metallic binding sites at the heart of the cluster-surface can be an important factor influencing catalytic activity, occupying a position between traditional heterogeneous and homogeneous systems [6].…”

Section: Introductionmentioning

confidence: 99%

Fluxional behaviour of phosphole and phosphine ligands on triosmium clusters

Otero

Peña

Arce

et al. 2015

Journal of Organometallic Chemistry

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The unsaturated cluster [Os 3 (µ-H) 2 (CO) 10 ] reacts with a variety of-conjugated phosphole ligands: 2,5-bis(2-thienyl)-1-phenylphosphole, 2,5-bis(2-pyridyl)-1-phenylphosphole, and 1,2,5triphenylphosphole, to give the monosubstituted [Os 3 (µ-H)(H)(CO) 10 (P)] and [Os 3 (µ-H) 2 (CO) 9 (P)] derivatives. Variable-temperature 1 H NMR studies for the decacarbonyltriosmium complexes show that the hydride ligands undergo fluxional behavior and its decarbonylation gave the nonacarbonyl unsaturated species with equivalent hydrides. An X-ray crystallographic analysis of [Os 3 (µ-H) 2 (CO) 9 (P)] (2b) (P = 1,2,5-triphenylphosphole) is reported. From 2,5-bis(2-pyridyl)-1phenylphosphole four isomers are obtained, the 1 H NMR spectrum at low temperature indicates that the phosphole ligand may occupy pseudoaxial and equatorial sites at one of the osmium atoms bearing the bridging hydride. The reaction of [Os 3 (CO) 10 (CH 3 CN) 2 ] with cyanoethyldiphenylphosphine affords mono-and bis(phosphine)-substituted clusters. The X-ray crystal structure of the monosubstituted [Os 3 (CO) 11 (η 1-PC 15 H 14 N)] (3) derivative is discussed. The dynamic behavior observed for [Os 3 (CO) 10 (η 1-PC 15 H 14 N) 2 ] (4) is studied by variable-temperature 1 H and 31 P{ 1 H} NMR spectroscopy. The latter studies show a mixture of two geometric isomers,

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A new member of the (HRhL2)x cluster class: [(.mu.-H)Rh(1,5-cyclooctadiene)]4

Cited by 41 publications

References 0 publications

The story of a mechanism-based solution to an irreproducible synthesis resulting in an unexpected closed-system requirement for the LiBEt3H-based reduction: The case of the novel subnanometer cluster, [Ir(1,5-COD)(μ-H)]4, and the resulting improved, independently repeatable, reliable synthesis

The story of a mechanism-based solution to an irreproducible synthesis resulting in an unexpected closed-system requirement for the LiBEt3H-based reduction: The case of the novel subnanometer cluster, [Ir(1,5-COD)(μ-H)]4, and the resulting improved, independently repeatable, reliable synthesis

Synthesis and Reactivity of Ester‐Functionalized 5‐Membered Rh^I‐κ²‐C,O‐Chelates and Their Relevance in Rh(cod)‐Mediated Carbene Polymerization

Fluxional behaviour of phosphole and phosphine ligands on triosmium clusters

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A new member of the (HRhL2)x cluster class: [(.mu.-H)Rh(1,5-cyclooctadiene)]4

Cited by 41 publications

References 0 publications

The story of a mechanism-based solution to an irreproducible synthesis resulting in an unexpected closed-system requirement for the LiBEt3H-based reduction: The case of the novel subnanometer cluster, [Ir(1,5-COD)(μ-H)]4, and the resulting improved, independently repeatable, reliable synthesis

The story of a mechanism-based solution to an irreproducible synthesis resulting in an unexpected closed-system requirement for the LiBEt3H-based reduction: The case of the novel subnanometer cluster, [Ir(1,5-COD)(μ-H)]4, and the resulting improved, independently repeatable, reliable synthesis

Synthesis and Reactivity of Ester‐Functionalized 5‐Membered RhI‐κ2‐C,O‐Chelates and Their Relevance in Rh(cod)‐Mediated Carbene Polymerization

Fluxional behaviour of phosphole and phosphine ligands on triosmium clusters

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Synthesis and Reactivity of Ester‐Functionalized 5‐Membered Rh^I‐κ²‐C,O‐Chelates and Their Relevance in Rh(cod)‐Mediated Carbene Polymerization