Crystal structures of (μ2-η(2),η(2)-4-hydroxybut-2-yn-1-yl 2-bromo-2-methylpropanoate-κ(4) C (2),C (3):C (2),C (3))bis[tricarbonylcobalt(II)](Co-Co) and [μ2-η(2),η(2)-but-2-yne-1,4-diyl bis(2-bromo-2-methyl-propanoate)-κ(4) C (2),C (3):C (2),C (3)]bis[tricarbonylcobalt(II)](Co-Co)

C John McAdam; Stephen C Moratti; Brian H Robinson; Jim Simpson; Roderick G Stanley

doi:10.1107/S1600536814009659

Crystal structures of (μ2-η(2),η(2)-4-hydroxybut-2-yn-1-yl 2-bromo-2-methylpropanoate-κ(4) C (2),C (3):C (2),C (3))bis[tricarbonylcobalt(II)](Co-Co) and [μ2-η(2),η(2)-but-2-yne-1,4-diyl bis(2-bromo-2-methyl-propanoate)-κ(4) C (2),C (3):C (2),C (3)]bis[tricarbonylcobalt(II)](Co-Co)

Acta Crystallogr Sect E Struct Rep Online. 2014 Jun 23;70(Pt 7):9-13. doi: 10.1107/S1600536814009659. eCollection 2014 Jul 1.

Authors

C John McAdam¹, Stephen C Moratti¹, Brian H Robinson¹, Jim Simpson¹, Roderick G Stanley¹

Affiliation

¹ Department of Chemistry, University of Otago, PO Box 56, Dunedin, New Zealand.

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 octa-carbonyl by the alkynes 4-hy-droxy-but-2-ynyl 2-bromo-2-methyl-propano-ate and but-2-yne-1,4-diyl bis-(2-bromo-2-methyl-propano-ate), respectively. Both mol-ecules have classic tetra-hedral C2Co2 cluster cores with the Co(II) atoms in a highly distorted octa-hedral 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 mol-ecules into inter-connected 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. Inter-connected columns of mol-ecules again form along the b-axis direction.

Keywords: alkyne-hexacarbonyl-dicobalt complex; alkynes; crystal structure.