Synthesis and properties of dimeric cobalt(III) dithiocarbamate complexes [Co2(R2dtc)5]+: X-ray structural analysis of pentakis(diethyldithiocarbamato)dicobalt(III) tetrafluoroborate

Abstract

The synthesis, properties, and structures of cationic dimeric dithiocarbamato-complexes (dtc) of cobalt(III) are described. The complexes [Co₂(R₂dtc)₅]BF₄ were prepared by reaction of [Co(R₂dtc)₃] with boron trifluoride. The crystal structure of [Co₂(Et₂dtc)₅]BF₄ was determined from three-dimensional counter data. Crystals are orthorhombic, space group P2₁2₁2₁, with a= 14.301(5), b= 16.819(3). c= 18.048(4)Å, and Z= 4. The structure was solved by conventional Patterson and Fourier techniques and refined by block-diagonal least-squares to R 0.092 for 1 141 independent reflections. The green-brown diamagnetic [Co₂(R₂dtc)₅]⁺ species is comprised of an electrophilic [Co(R₂dtc)₂]⁺ fragment co-ordinated in the cis-positions by sulphur atoms from an octahedral [Co(R₂dtc)₃] molecule of opposite chirality. The lability of the bridging groups renders the dimer susceptible to attack by other nucleophiles and representative mixed chelates of the type [Co(R₂dtc)₂(chel)] have been synthesised (chel = xanthate, dithiocarbamate, acetyl-, and dithioacetyl-acetonate).