Abstract. The reaction of the tetranuclear iron complex [μ₄-Sulfido-bis{(μ-2-furylmethanethiolato) bis[tricarbonyliron](Fe—Fe)}] 1 with PPh₃ was explored. The reaction leads to the formation of the monosubstituted complex [Fe₂.μ-2-furylmethanethiolate)₂.(CO)₅.(PPh₃)] 2. X-ray crystal structure has been reported for complex 2. Complexes 1 and 2 were found to be active catalysts for proton reduction. Complexes 1 and 2 showed comparable catalytic activity for proton reduction to dihydrogen.

Supramolecular coordination complex [(Re(CO)₃)₂(dhnq)(L²)] (3) containing two fac-Re(CO)₃ cores, rigid dianionic dhnq (H2-dhnq = 6,11-dihydroxy-5,12-naphthacenedione) motif and semi-rigid ditopic nitrogen donor 1,2-bis(2-nonylbenzimidazol-1-ylmethyl)benzene (o-Nbenzbix = L²) was synthesized.Compounds o-Nbenzbix and 3 were characterized using various analytical and spectroscopic methods. The electrochemical properties of 3 were studied using cyclic voltammetric measurements. SCCs [(Re(CO)₃)₂(-dhnq)(L¹)] (1) and [(Re(CO)₃)₂(dhaq)(L¹)] (2) possessing p-xylene spacer 1,4-bis(2-nonylbenzimidazol-1-ylmethyl)benzene (L¹) and 1,4-dihydroxy-9,10-anthraquinone (H2-dhaq) were also synthesized as reported previously. SCCs 1–3 were investigated via electrochemical methods. A plot of the Randles-Sevcik equation yielded a straight line for complex 3 thus, establishing that the redox processes were diffusion-controlled.