《有機金屬化學》課件Chapter 8

1、Chapter 8Carbene and Carbyne ComplexesOutlineIntroduction to M-C multiple bondsCommon synthetic routes to carbene complexesReactivity of carbene complexesCommon synthetic routes to carbyne complexesReactivity of carbyne complexesGeneral introduction to metal-carbonmultiple bonds. Carbene or alkylide

2、ne complexesVinylidene or alkylidene complexesAllenylidene complexesCarbyne or alkylidyne complexes1. Carbene or alkylidene complexes: There are many organometallic compounds containing metal carbon multiple bonds. e.g. 2. Vinylidene or alkylidene complexes: 3. Allenylidene complexes: 4. Carbyne or

3、alkylidyne complexes: Both carbene complexes are existent.A is Schrock carbenes and B is Fischer carbenes.ABSchrock carbenes:The carbene carbon will be attacked by Nu- or E+ ? Fisher carbenes :The carbene carbon will be attacked by Nu- or E+ ? Answer: The carbyne carbon is usually negatively charged

4、. Question 3. Which one is thermodynamically more stable? B. Common synthetic routes to carbene complexes (1). From metal carbonyls, e.g. (2). From isonitrile complexes. (3). From LnM-CR=CRR. (4). From LnM=C=CRR (5). From LnM-CXR2 thallium(6). By a-elimination. (7) How to prepare M=C=CR2 and M=C=C=C

5、R2 ? C. Reactivity of carbene complexes (1) Reactions of Fischer carbene with nucleophiles (3) Reactions with acetylenes Both Fischer and Schrock carbene can react with acetylenes. (4) Reactions with olefinsThere are at least there possible products for the reactions, depending on metal complexes an

6、d olefins used. e.g. (5) Other reactions D. Common synthetic routes to carbyne complexes(1) Lewis-acid-assisted abstraction of OR.(2) Electrophilic addition to M-CNR and M-CS (3) Transformation of M-C CR and M=C=CRR (4). By a-H elimination. e.g. E. Reactivity of MCR (1) Reactions with electrophiles e.g. (2) Reactions with acetylenes There are several possible products for the reactions, depending on metal complexes, and reaction conditions