COORDINATION NUMBER

Question

LEAST COORDINATION  NUMBER

A)Co2(CO)8 B)MN(CO)10

Answer 1

A)  Co2(CO)8 is known as dicobalt octacarbonyl and its structure is: 

• Here each Co atom is surrounded by 4 CO ligands and 1 Co atom. 
• So 1 Co atom is surrounded by total of 5 atoms. 
• Therefore coordination number of Co is 5.

B) Mn may bind itself with CO ligand as [Mn(CO)5]^- carbonylate ion, [Mn(CO)6]⁺ or polynuclear dimeric non-bridged complex, [Mn2(CO)10]. 

• In case of polynuclear M-M complexes, Metal-Metal bond is covalent and only one electron is added to EAN. 
• So, Coordination number of Mn is 6.