Metal complexes - 18electron rule and LFSE.

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In summary, the first conversation discussed the factors that contribute to a stronger ligand field in nitro ligands compared to nitrito ligands. The second conversation mentioned the lack of Jahn-Teller distortion in the complex trans-diaquaporphyrinatomanganese(III) ion due to the stability of macrocyclic ligands. The third conversation mentioned the application of the 18-electron rule to various types of complexes.
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Twickel
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Hi
The nitro ligand creates a stronger ligand field than the nitrito ligand because
Answer

a. O is more electronegative than N

b. the O atom can be a π-acceptor

c. the metal-N bond is shorter

d. the N atom can be a π-acceptor

e. b and d

I ruled out B and therefore E, since oxygen is a pi donor atom. Both ligands contain two Os and one N, both are 2+ charged. The only thing I can think of that would result in higher ligand field is forming shorter bonds. Is the answer therefore C?

The complex trans-diaquaporphyrinatomanganese(III) ion has a magnetic moment of 4.9 B.M. Jahn-Teller distortion is not observed in this complex because
Answer

a. the porphyrin is a macrocyclic ligand

b. water is a weak-field ligand

c. there is no degeneracy in the eg* orbitals

d. it is low-spin d4

e. it is high-spin d4

macrocycles form very stable bonds, they create a large splitting and therefore force the Mn(III) into a low spin configuration, is the answer then E or A or C, since all of them result in the same thing.

The 18-electron rule applies to
Answer

a. square-planar Pt(II) complexes

b. octahedral Ni(II) complexes

c. only metal carbonyl complexes

d. high-spin complexes

e. strong-field ligand complexesSquare planar complexes follow 16e rule. Octahedral Ni(II), that would be more then 18 electrons. Can not be C, since ligands other then CO form 18 electron complexes, must be E? Since strong ligands force the eg orbitals out of range for electrons

Help is much appreciated.
 
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Thank you.The answer to the first question is C. The answer to the second question is A, E, and C. The answer to the third question is E.
 

FAQ: Metal complexes - 18electron rule and LFSE.

What is the 18-electron rule?

The 18-electron rule is a guideline used in chemistry to predict the stability and reactivity of transition metal complexes. It states that most stable metal complexes have 18 valence electrons, which can be achieved by either fully filling or half-filling the d orbitals of the central metal atom.

What is the significance of the 18-electron rule?

The 18-electron rule is significant because it helps predict the stability and reactivity of metal complexes. It also serves as a useful tool for designing and synthesizing new metal complexes with specific properties.

What is the meaning of LFSE in metal complexes?

LFSE stands for Ligand Field Stabilization Energy, which is the energy gained by a metal ion when it is surrounded by ligands. It is a measure of the stability of a metal complex and is influenced by the nature of the ligands and the electronic configuration of the metal ion.

How does the 18-electron rule relate to LFSE?

The 18-electron rule is closely related to LFSE because it helps determine the number of valence electrons in a metal complex, which in turn affects the strength of the ligand field and the overall stability of the complex. A metal complex with 18 valence electrons is expected to have a lower LFSE and therefore be more stable than one with a different number of valence electrons.

Are there any exceptions to the 18-electron rule and LFSE?

Yes, there are some exceptions to the 18-electron rule and LFSE. For example, metal complexes with highly electronegative ligands or with metal ions in high oxidation states may deviate from the 18-electron rule. Additionally, some compounds may exhibit electronic structures that do not follow the expected ligand field splitting predicted by LFSE.

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