Propane reactions with cyclopentadienyl

The unsubstituted cyclopentadienyl analogue of 1 Cp(CO)2lr similarly gave Cp(CO)Ir(CH3)H. The hydridomethyl compound 9 was not prepared directly from the dihydride 4 due to experimental difficulties. However, Bergman observed that primary alkyl complexes are thermodynamically more stable than secondary complexes [26]. For example, the reaction of 4 with n-propane (reaction 9) or n-pentane gave mixtures of primary and secondary insertion products (with preferential formation of primary compounds). Treating these mixtures at 110 °C converts the secondary complexes into the more stable primary derivatives this conversion takes place via reversible reductive elimination from the secondary hydrido alkyl isomers. This very interesting result allowed the preparation of selectively pure primary insertion products of linear alkanes and the achievement of methane activation (reaction 12). Thus, heating the secondary hydrido cyclohexyl compound 6 in cyclooctane under CH4 pressure caused the formation of the methyl product 9 which is the thermodynamic sink for the system. 

---