Stereoretentive Ligand Exchange Reactions of N-Fused Porphyrin Ruthenium(II) Complexes.

ABSTRACT

The ligand exchange reactions of the ruthenium(II) complex of N-fused tetraphenylporphyrin, Ru(NFp)(CO)2Cl (2), with various anions were investigated. The chloride ligand of the isomers 2a-c was stereoretentively exchanged with bromide (Br-), iodide (I-), and acetate (AcO-) anions in toluene at 100 °C, structures of which were confirmed by 1H NMR as well as single crystal X-ray diffraction analysis. The silver (AgOAc, AgOTf) and boron (NaBPh4) reagents also afforded the corresponding stereoretentive products. On the other hand, the reaction with NaBH4 afforded the hydride complex Ru(NFp)(CO)2H (7) with low stereospecificity, showing a higher reactivity of 2c than other isomers. The ligand dissociation mechanism was proposed with the help of theoretical calculations on the plausible five-coordinated intermediates.