An Improved Protocol for the Synthesis of [(η4-C4R4)Co(η5-C5H5)] Complexes

Bertrand, Guillaume; Tortech, Ludovic; Fichou, Denis; Malacrìa, Max; Aubert, Corinne; Gandon, Vincent

doi:10.1021/om200662g

Cited by 29 publications

(18 citation statements)

References 62 publications

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“…The crystal structure of 3 reveals a dinuclear structure, where the bridging group is a tetraphenylcyclobutadienyl ligand. This is an unprecedented coordination mode for the C 4 -ring of this dianion that ordinarily binds in an Z 4 -manner to one metal only 42 . Close inspection reveals that two of the phenyl rings on one side of the four-membered ring exhibit close contacts, one to each uranium (U1 Á Á Á C67 2.887(5), U2 Á Á Á C85 2.842(5) Å), to give a m:Z 5 Z 5 -coordination mode overall.…”

Section: Synthesismentioning

confidence: 99%

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Reductive assembly of cyclobutadienyl and diphosphacyclobutadienyl rings at uranium

et al. 2013

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Despite the abundance of f-block-cyclopentadienyl, arene, cycloheptatrienyl and cyclooctatetraenide complexes, cyclobutadienyl derivatives are unknown in spite of their prevalence in the d-block. Here we report that reductive [2 þ 2]-cycloaddition reactions of diphenylacetylene and (2,2-dimethylpropylidyne)phosphine with uranium(V)-inverted sandwich 10p-toluene tetra-anion complexes results in the isolation of inverted sandwich cyclobutadienyl and diphosphacyclobutadienyl dianion uranium(IV) complexes. Computational analysis suggests that the bonding is predominantly electrostatic. Although the c 4 molecular orbital in the cyclobutadienyl and diphosphacyclobutadienyl ligands exhibits the correct symmetry for d-bonding to uranium, the dominant covalent contributions arise from p-bonding involving c 2 and c 3 orbital combinations. This contrasts with uranium complexes of larger arenes and cyclo-octatetraenide, where d-bonding dominates. This suggests that the angular requirements for uranium to bond to a small four-membered ring favours p-bonding, utilizing 5f-instead of 6d-orbitals, over d-bonding that is favoured with larger ligands, where 6d-orbitals can become involved in the bonding.

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Section: Synthesismentioning

confidence: 99%

“…This contrasts with d-block systems that readily and efficiently execute [2 þ 2]-cycloadditions of alkynes to give cyclobutadienyl complexes 42 .…”

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confidence: 99%

Reductive assembly of cyclobutadienyl and diphosphacyclobutadienyl rings at uranium

et al. 2013

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“…In contrast with preceding studies, microwave-assisted synthesis proved to be highly chemoselective and yielded pure complexes in almost all cases. 241…”

Section: Procedures Using Microwave Irradiationmentioning

confidence: 99%

Alternative Technologies That Facilitate Access to Discrete Metal Complexes

et al. 2019

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Organometallic complexes: these two words jump to the mind of the chemist and are directly associated with their utility in catalysis or as a pharmaceutical. Nevertheless, to be able to use them, it is necessary to synthesize them, and it is not always a small matter. Typically, synthesis is via solution chemistry, using a roundbottom flask and a magnetic or mechanical stirrer. This review takes stock of alternative technologies currently available in laboratories that facilitate the synthesis of such complexes. We highlight five such technologies: mechanochemistry, also known as solvent-free chemistry, uses a mortar and pestle or a ball mill; microwave activation can drastically reduce reaction times; ultrasonic activation promotes chemical reactions because of cavitation phenomena; photochemistry, which uses light radiation to initiate reactions; and continuous flow chemistry, which is increasingly used to simplify scaleup. While facilitating the synthesis of organometallic compounds, these enabling technologies also allow access to compounds that cannot be obtained in any other way. This shows how the paradigm is changing and evolving toward new technologies, without necessarily abandoning the round-bottom flask. A bright future is ahead of the organometallic chemist, thanks to these novel technologies. CONTENTS1. Introduction 7530 2. Technologies 7530 2.1. Grinding and Milling 7530 2.2. Microwave Irradiation 7531 2.3. Ultrasound Activation 7531 2.4. Photochemistry 7532 2.5. Continuous Flow 7532 3. Contribution of Each Technology Compared to Classical Syntheses 7533 4. Lithium and Magnesium 7534 4.1. Mechanochemical Access to Grignard Reagents 7534 4.2. Microwave Irradiation for the Synthesis of Magnesium Complexes 7534 4.3. Ultrasonic Procedures 7535 4.4. Continuous Flow Syntheses 7535 5. Groups 2, 3, 4, and 5 7537 5.1. Mechanochemical Procedures for Complexes of Groups 2, 3, and 4 7537 5.2. Microwave Irradiation for the Synthesis of Vanadium Complexes 7537 5.3. Synthesis of Vanadium Complexes Using Ultrasound 7538 6. Group 6 7538 6.1. Mechanosynthesis of Molybdenum and Chromium Complexes 7538 6.2. Microwave Irradiation for the Synthesis of Group 6 Metal Complexes 7539 6.3. Photochemistry for Synthesis of Group 6 Metal Complexes 7543 6.4. Continuous Flow Chemistry for Synthesis of Chromium Complexes 7545 7. Group 7 7545 7.1. Mechanosynthesis of Rhenium Complexes 7545 7.2. Microwave Irradiation for the Synthesis of Group 7 Metal Complexes 7546 7.3. Photochemical Synthesis of Manganese and Rhenium Complexes 7549 8. Group 8 7550 8.1. Synthesis of Iron and Ruthenium Complexes Using Ball Milling 7550 8.2. Microwave Procedures 7552 8.3. Ultrasonic Irradiation for Iron Complexes 7562 8.4. Syntheses of Iron and Ruthenium Complexes Using Photochemistry 7563 8.5. Continuous Flow Conditions to Prepare Iron and Ruthenium Complexes 7566 9. Group 9 7566 9.1. Synthesis of Cobalt and Rhodium Complexes by Mechanochemistry 7566 9.2. Procedures Using Microwave Irradiation 7569 9.3. Photochemical Synthesis of Iridium Complexes 7...

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“…Synthesis of nano-scale cube[101,102] Scheme 66. Microwave assisted synthesis of (η 5 -Cp)Co(η 4 -Cb) [31b] Synthesis of π-conjugated oligothiophene substituents on the Cb ring[88,103] Hamilton and coworkers have synthesized tetrapyridyl (283), tetrathienyl (286) and tetranaphthyl (287) derivatives of (η5 -Cp)Co(η 4 -Cb) by microwave assisted reaction of acetylenes with CpCo(CO) 2 at elevated temperatures in xylene (Scheme 66). Compared with traditional thermal approach, this method resulted in better yields of cyclopentadienone complexes relative to cyclobutadiene complexes (with the exception of 286) and in dramatically reduced reaction time [31b].…”

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confidence: 99%