Alternative Technologies That Facilitate Access to Discrete Metal Complexes

Abstract

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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