Syntheses and photocatalytic properties of ruthenium(II) complexes with ferrocenyl-functionalised enaminonate ligands

Treatment of [RuCl2(dmso)(4)] (dmso = dimethyl sulfoxide) with ferrocenylformyl acetone and ferrocenyl enaminone Fc-C(O)CH=C(CH3)N(H)CH2CH2NH2 (Fc = ferrocenyl, HL1) in a 1:1:1 molar ratio in the presence of CH3ONa in methanol afforded a ruthenium(II) complex [(Fc-C(O)CHC(O)CH3)Ru(dmso)(L1)] (1) with a pi-conjugated tridentate Schiff base ligand and a [(Fc-C(O)CHC(O)CH3)](-)ligand. Similar reactions between [RuCl2(dmso)(4)] and Fc-C(O)CH=C(CH3)N(H)Ar (Ar = C6H5, HL2; Ar = 4-ClC6H4, HL3; Ar = 2-MeC6H4, HL4; Ar = 2-OMeC6H4, HL5) afforded corresponding ruthenium(II) complexes [Ru(L2)(2)(dmso)(2)] (2), [Ru(L3)(2)(dmso)(2)] (3), [Ru(L4)(2)(dmso)(2)] (4), and [Ru(L5)(2)(dmso)(2)] (5) with pi-conjugated bidentate Schiff base ligands. Complexes 1-5 were well characterized by infrared, UV/Vis and NMR spectroscopies along with their electrochemical properties. The molecular structure of complex 1 center dot Et2O has been established by single-crystal X-ray diffraction. The photocatalytic properties for H-2 evolution by reduction of water of complexes 1-5 were also investigated in the paper. (C) 2021 Elsevier B.V. All rights reserved.