Abstract

Ferrocenyl dithiophosphonate metal-based molecular compounds are infrequent with untapped potential in electrocatalysis and luminescence. A stoichiometric reaction of late 3d metal(II) (Co, Ni, Cu) salts with ferrocenyl dithiophosphonate NH 4[S 2P(O nPr)Fc] in a 1:2 ratio produces mononuclear [M{S 2P(O nPr)Fc} 2] {M = Co II (1), Ni II (2)} complexes and a tetranuclear [Cu 4{S 2P(O nPr)Fc} 4] (3) {Fc = Fe(η 5-C 5H 4)(η 5-C 5H 5)} cluster. The distinct core of 3 compared to 1 and 2 indicates that NH 4[S 2P(O nPr)Fc] first serves as a sacrificial reductant and subsequently stabilizes the Cu(I) cluster. Heterometallic species (1-3) were characterized by NMR ( 1H, 31P), FT-IR, TGA, UV-visible spectroscopy, ESI-MS, XPS, and single-crystal X-ray diffraction. Ligand [S 2P(O nPr)Fc] - stabilized the redox-derived tetrahedral Cu I core of 3 and the M(II)-centered square (MS 4) frame in 1 and 2 through (η 3; μ 1, μ 2) and (η; μ 1, μ 1) bonding patterns, respectively. The irreversible single wave voltammogram indicated nonuniform electrochemical behavior of 1-3. TD-DFT indicates MLCT and weak LLCT in isostructural 1-2 and 3m [Cu II{S 2P(O nPr)Fc} 2], while 3 exhibits multielectron transitions with two types of MLCT. Third-order decay confirms singlet fluorescence, and multiple electronic transitions in 3 enhance its photoluminescence (27.5% QY) relative to 1-2, correlating the isostructural and different nuclearity features of late 3d metals with their physical and electrochemical properties.