Crystal structures of (μ2-η2,η2-4-hydroxybut-2-yn-1-yl 2-bromo-2-methylpropanoate-κ4C2,C3:C2,C3)bis[tricarbonylcobalt(II)](Co—Co) and [μ2-η2,η2-but-2-yne-1,4-diyl bis(2-bromo-2-methylpropanoate)-κ4C2,C3:C2,C3]bis[tricarbonylcobalt(II)](Co—Co)

Abstract

The title compounds, [Co2(C8H11BrO3)(CO)6], (1), and [Co2(C12H16Br2O4)(CO)6], (2), result from the replacement of two carbonyl ligands from dicobalt octacarbonyl by the alkynes 4-hydroxybut-2-ynyl 2-bromo-2-methylpropanoate and but-2-yne-1,4-diyl bis(2-bromo-2-methylpropanoate), respectively. Both molecules have classic tetrahedral C2Co2 cluster cores with the CoII atoms in a highly distorted octahedral coordination geometry. The alkyne ligands both adopt a cis-bent conformation on coordination. In the crystal structure of (1), classical O—H...O and non-classical C—H...O contacts form inversion dimers. These combine with weak O...O and Br...O contacts to stack the molecules into interconnected columns along the b-axis direction. C—H...O and C—H...Br contacts stabilize the packing for (2), and a weak Br...O contact is also observed. Interconnected columns of molecules again form along the b-axis direction.

Keywords

• crystal structure
• alkynes
• alkyne-hexacarbonyl-dicobalt complex