CrCl2DME

CrCl2DME is a chromium(II) coordination compound composed of a chromium center, two chloride ligands and one 1,2‑dimethoxyethane (DME) ligand. The empirical formula is CrCl2(DME). It is typically isolated as a dark green crystalline solid that is paramagnetic and highly sensitive to oxygen and moisture. The compound can be prepared by reacting anhydrous chromium(II) chloride with excess DME in an inert atmosphere, often in tetrahydrofuran or acetonitrile as solvent. The reaction is conducted below 0 °C and the product is purified by recrystallization from a mixture of dry solvent and a small amount of hexane.

In the solid state the chromium center is six‑coordinate. The geometry is best described as distorted octahedral, with the two chloride ions bound axially and the bidentate DME occupying two equatorial positions. Two additional ligand sites are typically occupied by solvent molecules or are labile and can undergo substitution reactions. The presence of the DME ligand acts to stabilize the low‑valent chromium center and influences the redox potential of the complex.

Chemically, CrCl2DME serves as a mild reducing agent and a precursor to higher‑valent chromium species. It is employed in the synthesis of organochromium complexes and in oligomerization reactions of olefins. In organic synthesis it is used to transfer a Cr(II) fragment to unsaturated substrates, often under catalytic conditions. The reagent’s air‑sensitivity necessitates handling under nitrogen or argon, and exposure to water or oxygen leads to rapid oxidation to Cr(III) oxides.

CrCl2DME has been studied by X‑ray diffraction, spectroscopic methods, and electrochemical measurements. Its electrochemical behavior shows a reversible one‑electron oxidation at a potential that is more negative than that of analogous nickel and iron dithiocarbamate complexes, reflecting the unique electronic structure conferred by the chloride ligands and the DME backbone.