C-H Bond Activation

A carbon-hydrogen bond is broken and replaced with a carbon-X bond in a process known as carbon-hydrogen bond functionalization (C-H functionalization) (where X is usually carbon, oxygen, or nitrogen). The phrase often suggests that the C-H cleavage process involves a transition metal. To generate an organometallic complex, in which the hydrocarbon is coordinated to the inner-sphere of a metal, either via an intermediate "alkane or arene complex" or as a transition state leading to a "MC" intermediate, the hydrocarbon must first react with a metal catalyst. This first step's intermediate, which is commonly referred to as C-H activation but is more properly known as C-H functionalization, might then go through further reactions to get the functionalized product. Important to this definition is the requirement that during the C–H cleavage event, the hydrocarbyl species remains associated in the inner-sphere and under the influence of "M".