cyanide

[reva_bajjuri]

could someone explain why cyanide cannot form two coordinate covalent bonds? prof. lavelle said that in the lecture from last week

[Stuti Pradhan 2J]

Cyanide does have 2 lone pairs, but since it has a triple bond and is linear, the molecule cannot orient itself in a way the both lone pairs bond to the same transition metal.

To have a polydentate ligand, you need at least two lone pairs and at least one spacer between the two lone pairs. Cyanide does not have a spacer atom and it also has a triple bond which is very strong and not flexible, so it cannot bend or orient in any way to bond twice with one TM.

Hope this helps!

[Maaria Abdel-Moneim 2G]

Because cyanide has a triple bond it cannot orient in a way where both lone pairs can bond to the transition metal. In order for something to be polydentate it has to be able to orient where each lone pair can bond easily.

[Sara_Lim_2C]

Cyanide doesn't have spacer atom(s) that allow the lone pairs on either side of the linear atom to bond to the transition metal. Because of that, only one of the lone pairs can bond to the transition metal.