What a Difference One Electron Makes! Generating Low-Coordinate Ti–C and V–C Multiply Bonded Frameworks through One Electron Oxidatively Induced α-Hydrogen Abstractions

Low-coordinate, high oxidation state titanium and vanadium complexes containing terminal metal–carbon multiply bonded functionalities have been prepared directly or indirectly through one electron oxidatively induced α-hydrogen abstraction reactions. This synthetic approach offers a mild entry to reactive M=C and M≡C motifs, and does not depend on external stimulants such as heat, light or base to promote the α-hydrogen-abstraction step. In addition, this strategic protocol avoids the use of powerful electrophiles, thus generating terminal and nucleophilic M–C multiple bonds in low-coordination environments. In some cases terminal alkylidenes containing β-hydrogen atoms can also be introduced through this route. This microreview surveys the synthesis and chemistry surrounding isolable titanium and vanadium complexes bearing terminal alkylidene and alkylidyne ligands. Particular emphasis will be placed on the synthesis of the high oxidation state M–C multiple bond. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

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