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Ch.23 - Transition Metals and Coordination Chemistry
Brown - Chemistry: The Central Science 14th Edition
Brown14th EditionChemistry: The Central ScienceISBN: 9780134414232당신이 사용하는 게 아니라요?교과서 변경
23장, 문제 8

Which of these crystal-field splitting diagrams represents:
a. a weak-field octahedral complex of Fe³⁺ ,
b. a strong-field octahedral complex of Fe³⁺ 
c. a tetrahedral complex of Fe³⁺
d. a tetrahedral complex of Ni²⁺ (The diagrams do not indicate the relative magnitudes of ∆. ) [Find more in Section 23.6.]

검증된 단계별 안내
1
Identify the electron configuration of Fe³⁺ and Ni²⁺. Fe³⁺ has an electron configuration of 3d^5, and Ni²⁺ has an electron configuration of 3d^8.
Understand the concept of crystal field splitting in different geometries. In octahedral complexes, the d-orbitals split into two energy levels: t2g (lower energy) and eg (higher energy). In tetrahedral complexes, the splitting is reversed with eg (lower energy) and t2g (higher energy).
For a weak-field octahedral complex of Fe³⁺, the electrons will fill the t2g and eg orbitals according to Hund's rule and the Aufbau principle, with minimal pairing due to the lower crystal field splitting energy.
For a strong-field octahedral complex of Fe³⁺, the electrons will first fill the lower energy t2g orbitals completely before occupying the higher energy eg orbitals, showing more electron pairing due to higher crystal field splitting energy.
For tetrahedral complexes of Fe³⁺ and Ni²⁺, distribute the electrons in the eg and t2g orbitals according to their respective electron configurations, considering the reversed order of energy levels compared to octahedral complexes.

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주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Crystal Field Theory

Crystal Field Theory (CFT) explains the electronic structure of transition metal complexes by considering the interaction between the metal ion's d-orbitals and the electric fields produced by surrounding ligands. This theory helps predict the splitting of d-orbitals into different energy levels, which is crucial for understanding the color, magnetism, and stability of the complexes.
추천 영상:
가이드 코스
01:18
The study of ligand-metal interactions helped to form Ligand Field Theory which combines CFT with MO Theory.

Octahedral vs. Tetrahedral Complexes

In coordination chemistry, octahedral complexes have six ligands symmetrically arranged around a central metal ion, leading to a specific pattern of d-orbital splitting. Tetrahedral complexes, on the other hand, have four ligands and exhibit a different splitting pattern. The geometry of the complex significantly influences the energy difference between the split d-orbitals, denoted as Δ.
추천 영상:
가이드 코스
01:28
For octahedral complexes, Weak-Field Ligands create High-spin complexes and Strong-Field Ligands create Low-spin complexes.

Weak-field vs. Strong-field Ligands

Ligands can be classified as weak-field or strong-field based on their ability to split the d-orbitals. Weak-field ligands cause a small splitting (Δ), leading to high-spin configurations, while strong-field ligands cause larger splitting, resulting in low-spin configurations. The nature of the ligands affects the electronic arrangement of the metal ion, influencing the properties of the complex.
추천 영상:
가이드 코스
02:40
Strong-Field Ligands result in a large Δ and Weak-Field Ligands result in a small Δ.