Divergent reactivity of 2-vinylpyridine and 1-vinylpyrazole in rhodium-phosphine systems: C-H activation and dinuclear chemistry

Abstract

The RhI-RhIII mixed valence dinuclear complex Rh2-Cl2(μ-H)(μ-η2,κ2-C,N-NC5H4-2-(Z)CH=CH)(PPhMe2)3 has been prepared by reaction of [Rh(μ-Cl)(η2-coe)2]2 with 2-vinylpyridine in the presence of dimethylphenylphosphine as a result of C-H activation of the terminal olefinic proton. The X-ray structure presents anagostic Rh···HC and π-π interactions between aromatic rings. In contrast, 1-vinylpyrazole does not undergo a C-H activation process, resulting in the formation of dinuclear species supported by 1-vinylpyrazole bridges. Anagostic Rh···HC interactions and CH···Cl hydrogen bonds are responsible for the 3D packing of the complex.