PHOTOLYSIS OF DIACYLFERROCENES AND THEIR PHOTO-LIGAND EXCHANGE-REACTIONS WITH 1,10-PHENANTHROLINE

The photolysis of 1,1'-diacylferrocenes Fc(COR)(2) (Fc=Ferrocenyl, R=C H3,Ph) in the presence of 1,10-phenanthroline (phen) in deoxygenated a cetonitrile under irradiation with visible light has been studied. In these photolysis systems the phen has two important roles to play: one is to stabilize the photo-liberated Fe2+ by coordination, and the oth er is to promote the photolysis through photo-ligand exchange. Under t his condition the photoproducts were isolated in definite composition and characterized by single crystal X-ray diffraction, H-1 NMR spectro scopy, IR spectroscopy, photolysis-cyclic voltammetry and elemental an alysis. The mechanism of the reactions was demonstrated to be charge t ransfer from metal to acylcyclopentadienyl ring, leading to cleavage o f the bond between them. The phen attacks the Fe2+ ion to give the sta ble tris (1,10-phenanthroline) iron(II) complex cation and the acylcyc lopentadienyl ring detaches from the Fe2+ ion, giving the enolate anio n in the outer sphere of the complex. Crystallographic data for photop roduct 1, [Fe(phen)(3)](C5H4COCH3)(2) . CH3CN . 2H(2)O: triclinic, spa ce group P-1 (No. 2), a=12.714(4), b=13.125(3), c=14.946(5) Angstrom, alpha=106.45(1), beta=112.13(3), gamma=79.60(2)degrees V=2208(1) Angst rom(3), R=0.041, R-w=0.052. Crystallographic data for photoproduct 2, [Fe(phen)(3)](C5H4COC6H5)(2) . 0.5C(6)H(6) . H2O: triclinic, space gro up P-1 (No. 2), a=12.218(4), b=12.410(3), c=16.989(2) Angstrom, alpha= 98.56(2), beta=102.06(2), gamma=100.98(3)degrees, V=2431(2) Angstrom(3 ),R=0.049, R-w=0.057.