Electron withdrawing and electron donating effects of 4,4 '-bipyridine substituents on ruthenium mono(bipyridine) complexes

Monobipyridine complexes of ruthenium (4,4'-L-2-2,2'-bpy)Ru(CO)(2)Cl-2 (L = H, Me. t-Bu, Cl, Br, H2PO3, NO2) were synthesised and structurally charact erised. The electronic effects of the substituents L on vibration and absor ption spectra were studied using both experimental and theoretical methods, calculations were carried out with the density functional hybrid B3PW91 an d Hartree-Fock ab initio methods. The energy differences between the HOMO a nd LUMO orbitals of the complexes depended on the electron withdrawing prop erties of the bipyridine substituents. The electronic effects of the substi tuents were observed as a correlation between the spectra (lambda (max) and nu (CO) bands) and the electronic character of the substituents.