Amongst the following, the total number of species which are diamagnetic is K4[Fe(CN)], K3[Cr(CN

Amongst the following, the total number of species which are...

Key Concepts

Diamagnetism

Diamagnetism is a magnetic property of substances in which all electrons are paired, resulting in a weak repulsion from an external magnetic field. In chemistry, a molecule or complex is considered diamagnetic if it has no unpaired electrons, which influences its magnetic susceptibility and behavior in the presence of magnetic fields.

Crystal Field Theory

Crystal Field Theory explains the electronic structure of transition metal complexes by considering the effect of the electrostatic field produced by surrounding ligands. This theory helps predict the splitting of the metal ion's d orbitals into sets of different energy levels, which in turn determines whether electrons will pair up or remain unpaired in specific orbital arrangements.

d-Electron Count

The d-electron count is crucial for understanding the electronic configuration of transition metal complexes. By determining the oxidation state of the metal ion and subtracting from its atomic number, the number of d electrons present is found. This information is fundamental when predicting the distribution of electrons in the split d orbitals and assessing the magnetic properties of the complex.

High Spin vs Low Spin Complexes

High spin and low spin configurations arise from the competition between the pairing energy of electrons and the energy difference (?) between split d orbitals. In a high spin complex, electrons occupy higher energy orbitals singly before pairing, leading to more unpaired electrons and paramagnetism. Conversely, in a low spin complex, electrons pair in the lower energy orbitals, often resulting in diamagnetism if all electrons are paired.

Ligand Field Strength

Ligand field strength refers to the ability of a ligand to split the d orbitals of a transition metal ion, which is summarized in the spectrochemical series. Strong field ligands produce a large splitting (high ?) that can lead to low spin configurations with paired electrons, while weak field ligands result in small splitting, often favoring high spin states with unpaired electrons. This concept is essential in predicting the magnetic behavior of coordination complexes.

Transcript

00:01 In this question we have been given some complexes and out of these given complexes we need to determine how many of them are diamagnetic now diamagnetic is a simple concept which says that the molecule must not be having any unpaired electrons there should not be any unpaired electrons and then the molecule or the complex would be called diamagnetic so first of all we have this molecule or the complex that is k4 f e cn6 now if we dissociate this complex then we get f e c n6 minus 4 so in this complex we can see that the central metal atom is iron with which has an atomic number of 26 so we get argon 3d 6 4 s 2 but again this iron is in plus 2 oxidation state which means that the effective electronic configuration would be rgan 3d 6 only right so if argon 3d 3d 3d 3 6 is there we can say that these 6 electrons would be arranged in this way and since there are cyanide ligands the cyanide ligands would tend to pair of these electrons and the newly formed arrangement of the d electrons would be like this where these six electrons would be completely paired so now we can say that since there is no unpaired electron in this complex we can see that this one is diamagnetic now moving on to the next complex which is a3 cocn6.

01:30 So again if we dissociate it we get our complex ion as cocn6 minus 3.

01:37 Here we have the central metal atom as cobalt which has an atomic number of 27 and having 27 atomic number it will be having an electronic configuration of argon 3d 7 4s 2.

01:51 Now again this cobalt is in plus 3 oxidation state which means that the effective electronic configuration will become argon 3d6 right now again just like the previous example argon 3d6 is the electronic configuration here and cyanide ligands are also there and similarly this complex will also be having all the paired electrons and no unpaired electrons and moving on to the next complex a2 n i cn4 so after dissociating we get the complex ion as nicn4 2 minus now here nickel is the central metal atom so nickel would be having an electronic configuration of argon 3d8 4 s 2 now in plus 2 oxidation state the effective electronic configuration would become argon 3d 8 because 2 electrons from 4 s would be eliminated now the d8 configuration would come look like this these are the 8 electrons again for cm the pairing would be there and the final arrangement of these the electrons would look like this.

03:04 So all the electrons are again paired and hence this molecule would also be diamagnetic.

03:09 Now moving on to the next complex which is c -o -n -363 -plus...

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