Tertiary phosphine-appended transition metal ferrocenyl dithiocarbamates: Syntheses, Hirshfeld surface, and electrochemical analyses

Abstract

Five new heteroleptic complexes of Cu(I), Ag(I), and Ni(II) having formulae [Cu3(dtc)2(dppf)2]PF6 (Cu-I), [Cu3(dtc)2(dppe)2]PF6 (Cu-II), [Cu(PPh3)2(dtc)] (Cu-III), [Ag3(dtc)2(PPh3)2]NO3 (Ag-I), and [Ni(dtc)(dppf)]PF6 (Ni-I) (dtc = N-ethanol-N-methylferrocenyl-dithiocarbamate; dppf = 1,1′-bis(diphenylphosphino)ferrocene; dppe = 1,1′-bis(diphenylphosphino)ethane; PPh3 = tripheylphosphine) have been synthesized and characterized using elemental analysis, Fourier-transform infrared, multinuclear nuclear magnetic resonance, UV–Vis spectroscopy, and single-crystal X-ray diffraction. The single-crystal X-ray diffraction studies indicate that Ag-I forms a rare trinuclear cluster in which the geometry around the two silver centers Ag1 and Ag3 is distorted tetrahedral, whereas the third silver center Ag2 shows a distorted trigonal planar geometry. The Ni-I complex has a distorted square-planar geometry around the Ni center. In addition, a side product [Ag2{S2(dppf)2}] (Ag-II) was obtained during an attempt to synthesize [Ag(dppf)(dtc)], where the two Ag centers are bridged by two sulfido centers and coordinated with two phosphorus centers of the dppf ligand to give rise to a distorted tetrahedral geometry. The solid-state structures of Ag-I, Ni-I, and Ag-II are stabilized by a variety of weak interactions. The nature of these interactions has been addressed with the help of Hirshfeld surface analyses. In addition, the weak argentophilic interaction in Ag-I and Ag-II have been studied using quantum theory of atoms in molecules and natural bond orbital calculations. The electrochemical properties of the complexes have been investigated using cyclic voltammetry, where Cu-I and Cu-II exhibited two quasi-reversible waves, whereas Cu-III, Ag-I, Ag-II, and Ni-I exhibited only one quasi-reversible peak.