Which of the following coordination compounds has bridging carbonyl ligand?

The correct option is [Co₂(CO)₈].

To determine which coordination compound contains bridging carbonyl (CO) ligands, let us analyze the structural features of each given metal carbonyl complex:
1. Bridging vs. Terminal Carbonyls: In metal carbonyls, CO ligands can coordinate to metal atoms in two primary ways:
- Terminal CO: The CO ligand is bonded to a single metal atom (M-CO).
- Bridging CO (μ-CO): The CO ligand is shared between two or more metal atoms (M-CO-M). Bridging carbonyls are common in polynuclear (multicenter) metal carbonyl complexes.

2. Analysis of the Options:
- [Cr(CO)₆]: This is a mononuclear carbonyl complex. It has an octahedral geometry with a single chromium (Cr) center. Because there is only one metal atom, all 6 CO ligands must be terminal. Therefore, it has no bridging carbonyl ligands.
- [Fe(CO)₅]: This is also a mononuclear carbonyl complex with a trigonal bipyramidal geometry around a single iron (Fe) center. Since it contains only one metal atom, all 5 CO ligands are terminal. It has no bridging carbonyl ligands.
- [Mn₂(CO)₁₀]: This is a dinuclear carbonyl complex. Its structure consists of two Mn(CO)₅ units joined by a single manganese-manganese (Mn-Mn) bond. All 10 CO ligands in this complex are terminal, meaning it has no bridging carbonyl ligands.
- [Co₂(CO)₈]: In the solid state, dicobalt octacarbonyl exists in a bridged form (C_2v symmetry). Its structure features a cobalt-cobalt (Co-Co) bond, six terminal CO ligands (three on each cobalt atom), and two bridging CO ligands that bridge the two cobalt atoms. Thus, it contains bridging carbonyl ligands.

Therefore, among the given coordination compounds, [Co₂(CO)₈] is the one that contains bridging carbonyl ligands.