STATEMENT-1: CO is stronger ligand than CN^(-) STATEMENT-2: CO and (2024)

FAQs

Is CO a stronger ligand than CN? ›

The invariant bond distances of the analogous iron(II) and -(III) porphyrinates are consistent with little π-back bonding between iron and cyanide. This conclusion is strengthened by the comparison with analogous carbonyl complexes. Clearly cyanide is a weaker 3eld ligand than CO in iron(II) porphyrinates.

Carbon monoxide is one of the most common, and strongest π acceptor ligands in inorganic chemistry. Refer to the molecular orbital diagram of CO and sketch likely metal-ligand orbital interactions for both sigma and pi bonding in a metal-CO complex.

Also, CN− acts as a strong field ligand because it can accept electrons from metal species. Carbon donor ligands are strong ligands and usually forms low spin complexes.

CO is a stronger Complexing reagent than NH3 because of back bonding. In case of CO, It is a good Sigma donor and a pi acceptor. There exists a back bonding in CO complexes which are a donation of electrons from the filled d orbital of metals to a pi molecular orbital of CO.

CO forms a more stable complex since it is involved in synergic effect.

The cyano ligand (CN^-)

This ligand is isoelectronic to the CO ligand. The N atom has one electron less than O, but the negative charge at the cyanide ligand compensates for that. One question we can ask is: What is the reactive end? The answer is: In analogy to the carbonyl ligand the reactive end is the carbon atom.

CO is a dative, L-type ligand that does not affect the oxidation state of the metal center upon binding, but does increase the total electron count by two units.

Carbon monoxide is a simple but fascinating ligand. We have previously noted that carbon monoxide, although a very poor base, is a strong field ligand due to the presence of π backbonding.

Ligands that bind through very electronegative atoms such as O and halogens are thus expected to be weak field, and ligands that bind through C or P are typically strong field. Ligands that bind through N are intermediate in strength.

Hydrocyanic acid (HCN) is a weak acid. Its conjugate base is CN^- which is a strong base.

Is CN a strong or weak nucleophile? ›

CN− is a strong nucleophile. We expect it to take part in SN2 reactions. It is also a weak base, so we do not expect either E2 or E1 eliminations. If an SN2 reaction is not possible, an SN1 reaction might occur.

According to theories, any acid that dissociates partially in aqueous solution is classified as a weak acid. Because the dissociation of HCN is partial in aqueous solution, it is a weak acid too. It releases a very small amount of hydrogen-ion in water.

It has to do with the energies of the frontier orbitals. As you rightly said, both species are isoelectronic, and the orbital energies in CO are lower than those in CN⁻. The lower hom*o energy means that CO is a poorer σ donor orbital towards the metal than CN⁻. Likewise the lower LUMO makes it a better π acceptor.

Other ligands such as CO and CN- can bind more strongly to the iron because they are better pi acceptors than oxygen, and the fact that they can block the O₂ binding site so effectively is what makes them so very toxic.

First of all N2 is a pathetic sigma donor due its non polarity. N2 is infact reduced in its complexes. CO on the other hand has negative charge over carbon atom so it becomes a powerful sigma donor. After donation back bonding occurs between metal atom and anti bonding orbital of carbon.

Answer and Explanation: Cyanide ion is a strong ligand. It will cause greater splitting between the respective orbitals.

The electronegativity of carbon is 2.55. The electronegativity of nitrogen is 3. The electronegativity of oxygen is 3.5.

C-N bond is stronger than the C-O bond as the electronegativity of N is lesser than oxygen.