Coordination Chemistry of the Parent Dithiocarbamate H2NCS2-: Organometallic Chemistry and Tris-Chelates of Group 9 Metals

Quentin Gaydon; D Scott Bohle

doi:10.1021/acs.inorgchem.1c03789

Coordination Chemistry of the Parent Dithiocarbamate H₂NCS₂^-: Organometallic Chemistry and Tris-Chelates of Group 9 Metals

Inorg Chem. 2022 Mar 21;61(11):4660-4672. doi: 10.1021/acs.inorgchem.1c03789. Epub 2022 Mar 9.

Authors

Quentin Gaydon¹, D Scott Bohle¹

Affiliation

¹ Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal H3A 0B8, Quebec, Canada.

PMID: 35261230
DOI: 10.1021/acs.inorgchem.1c03789

Abstract

Two tris-chelate complexes of cobalt and rhodium and two complexes of Ru(II) of dithiocarbamate, [S₂CNH₂]^-, were synthesized. The complexes were spectroscopically characterized by IR, NMR, UV-vis, and MS and structurally characterized by X-ray diffraction. The structural features of the rhodium complex were compared to those of other tris-chelate Rh(III) dithiocarbamate complexes and are characterized by a change in the ground-state geometry in comparison to expected octahedral tris-chelate complexes. This was confirmed both experimentally by X-ray diffraction and theoretically using DFT calculations. The inversion barriers of Rh(Bz₂dtc)₃, Ir(Bz₂dtc)₃, and Rh(Et₂dtc)₃ were determined using VT-NMR in DMSO. These barriers were found to be surprisingly low for heavy group 9 elements of d⁶ tris-chelate complexes: values of 16.7, 17.1, and 16.4 kcal/mol were calculated, respectively. By comparing structural features, we are able to determine that the activation barrier for the inversion of stereochemistry of Rh(H₂dtc)₃ must have a similarly low value. A modified version of the Bailar twist involving an intermediate with C_3h geometry was proposed as the mechanism of inversion.