Structures and electronic properties of cobalt(II) selone coordination complexes

Area of Science:

• Inorganic Chemistry
• Coordination Chemistry
• Structural Chemistry

Background:

• Selenourea ligands exhibit diverse structural chemistry.
• Coordination complexes involving cobalt and selenourea ligands are infrequently reported.
• Imidazole-2-selones are a class of selenourea ligands with potential in coordination chemistry.

Purpose of the Study:

• To synthesize and characterize novel cobalt(II) coordination complexes with 1,3-dialkyl-substituted imidazole-2-selone ligands.
• To investigate the solid-state structures of these new cobalt complexes.
• To compare the observed coordination modes with existing literature and explore factors influencing cobalt-selenium bond strengths.

Main Methods:

• Synthesis of cobalt(II) complexes using two different crystallization techniques.
• Single-crystal X-ray diffraction analysis to determine the solid-state structures of the complexes.
• Density functional theory (DFT) calculations to evaluate cobalt-selenium bond strengths.

Main Results:

• The solid-state structures of dichloridobis(1,3-diethylimidazole-2-selone-κSe)cobalt(II) and dichloridobis(1,3-diisopropylimidazole-2-selone-κSe)cobalt(II) were determined.
• Complexes predominantly exhibit terminal binding modes of the selenourea ligands, contrasting with bridging modes common in late d-block metals.
• DFT calculations indicated a trend in cobalt-selenium bond strengths: Me ≃ Et < iPr for 1,3-dialkyl-substituted imidazole-2-selones.

Conclusions:

• The study successfully synthesized and structurally characterized new cobalt(II)-selenourea complexes.
• The findings highlight the preference for terminal coordination modes in these specific cobalt complexes.
• A clear trend in cobalt-selenium bond strength related to alkyl substitution was computationally established, offering valuable structure-property relationships.