Question

The coordination geometry around the manganese in decacarbonyldimanganese(0) is

• A. Octahedral
• B. Trigonal bipyramidal
• C. Square pyramidal
• D. Square planar

Answer 1

The Correct Option is A

Solution: Decacarbonyldimanganese(0), represented as Mn(CO)₁₀, is a complex where manganese is surrounded by ten carbon monoxide ligands.

Coordination Number: In this complex, manganese exhibits a coordination number of 10, which typically leads to an octahedral geometry.

The carbon monoxide ligands are arranged around the manganese atom in a way that minimizes repulsion between the ligands, resulting in an octahedral shape.

Geometry: The octahedral arrangement is characteristic of complexes with a higher coordination number, where the ligands occupy the vertices of an octahedron around the central metal atom.

Thus, the coordination geometry around manganese in Mn(CO)₁₀ is: Octahedral

Answer 2

To determine the coordination geometry around manganese in decacarbonyldimanganese(0), we need to analyze the molecular formula and structure of the compound Mn₂(CO)₁₀.

Concept Used:

The compound decacarbonyldimanganese(0) has the formula Mn₂(CO)₁₀. It is a dimeric metal carbonyl where the manganese atoms are in the zero oxidation state. The total electron count and the metal-metal bonding determine the local coordination geometry around each metal center. A common structural motif for such dimers is two octahedral metal centers sharing a metal-metal bond, which acts as one coordination site for each metal.

Step-by-Step Solution:

Step 1: Identify the molecular formula and metal oxidation state. The compound is Mn₂(CO)₁₀, and the oxidation state of Mn is 0.

Step 2: Determine the total number of carbonyl ligands and their bonding mode. There are 10 CO ligands for 2 Mn atoms. In the most common and stable structure, there is one metal-metal (Mn-Mn) bond. This bond uses one coordination site on each Mn atom.

Step 3: Distribute the remaining ligands. With one site occupied by the Mn-Mn bond, each Mn atom needs five more ligands to complete its coordination sphere. In Mn₂(CO)₁₀, each Mn atom is bonded to five terminal CO ligands.

Step 4: Deduce the coordination number and geometry. Each Mn atom is bonded to five CO ligands and one Mn atom. This gives a coordination number of 6. A coordination number of 6 typically corresponds to an octahedral geometry.

Therefore, the coordination geometry around each manganese atom is octahedral.