A mixed valence zinc dithiolene system with spectator metal and reactor ligands

Abstract

Neutral complexes of zinc with N,N′-diisopropylpiperazine-2,3-dithione (iPr2Dt0) and N,N′-dimethylpiperazine-2,3-dithione (Me2Dt0) with chloride or maleonitriledithiolate (mnt2−) as coligands have been synthesized and characterized. The molecular structures of these zinc complexes have been determined using single crystal X-ray diffractometry. Complexes recrystallize in monoclinic P type systems with zinc adopting a distorted tetrahedral geometry. Two zinc complexes with mixed-valent dithiolene ligands exhibit ligand-to-ligand charge transfer bands. Optimized geometries, molecular vibrations and electronic structures of charge-transfer complexes were calculated using density functional theory (B3LYP/6-311G+(d,p) level). Redox orbitals are shown to be almost exclusively ligand in nature, with a HOMO based heavily on the electron-rich maleonitriledithiolate ligand, and a LUMO comprised mostly of the electron-deficient dithione ligand. Charge transfer is thus believed to proceed from dithiolate HOMO to dithione LUMO, showing ligand-to-ligand redox interplay across a d10 metal.

One dimensional metal dithiolene (M = Ni, Fe, Zn) coordination polymers for the hydrogen evolution reaction

“…Comprehensive study of metal dithiolenes found that cobalt, nickel and iron complexes display most often square planar geometries, 47,48 whereas zinc complexes display tetrahedral geometries. [49][50][51] Cobalt dithiolene species are among the most efficient molecular catalysts for the hydrogen evolution reaction (HER). 44,45,52-54 A higher activity for HER was observed for the cobalt dithiolene complex, [Co(bdt) 2 ] − , in a 1 : 1 mixture of water and acetonitrile, relative to the activity in a pure anhydrous organic solvent (100% acetonitrile).…”

The Impact of Ligand Oxidation State and Fold Angle on the Charge Transfer Processes of MoIVO‐Dithione Complexes

“…The C−C bond lengths of the Dt 0 moieties are similar in length to the C−C (C2‐C3) single bond of the methylene backbone of the Dt 0 ligand, which may be utilized as an “internal standard” for a C−C single bond. The C−S (C1‐S1 and C4‐S2) are of similar lengths to the C−S double bond observed in structurally characterized Dt 0 metal complexes, [3a,b,f–h,4a,b,5c,d] suggesting C−S double bond character. The bond distances and the 1 H NMR and IR spectral signatures suggest that the Dt 0 ligand maintains a fully oxidized in both solution and solid states.…”

Interligand communication in a metal mediated LL′CT system – a case study

“…S2 and S3 †). 31 The cyclic voltammogram of free i Pr 2 Dt 0 ligand exhibited two partially reversible reduction couples at À1887 mV (DE p ¼ 134 mV) and À2088 mV (DE p ¼ 141 mV), and [Zn(mnt)( i Pr 2 Dt 0 )] produces two partially reversible reduction couples at À939 mV (DE p ¼ 115 mV) and À1365 mV (DE p ¼ 125 mV). For 6 and [Zn(mnt)( i Pr 2 Dt 0 )], the ligand-based redox couples are shied by 802 mV and 948 mV, respectively for the rst couple and 604 mV and 723 mV for the second couple, respectively, compared to free i Pr 2 Dt 0 .…”