Reactive metallacycle

Reactions other than Lewis acid-base associations/dissociations are frequently observed wit donor molecules, leading notably to solvolysis, oxygen or sulfur abstraction, insertion reaction and carbon-carbon coupling reactions. The tendency to form metal-element multiple bonds i remarkable in this respect the activation of dinitrogen by tantalum or niobium is unique. Th formation and chemistry of constrained reactive metallacycles open another promisin fast-developing area, on the frontier with organometallic chemistry. 

B-2006MI59 I. Tomita Polymers possessing reactive metallacycles in the mainchain, in Macromolecules Containing Metal and Metal-... 

The sterics and electronics of the substituents on a reactive metallacycle play an essential role in the efficiency and selectivity of the corresponding metathesis... 

The cyclopropenone C-C bond undergoes oxidative addition to transition metals to form metallacyclobutenones. A four-membered platinacycle was confirmed by X-ray crystallographic analysis [163]. Reactive metallacycles are exploited in several catalytic reactions. 

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