Complexos, ligantes e cores mutáveis
Introduzido| English | Significado |
|---|---|
| ligand/ˈlɪɡænd/ | ligante |
| coordination number/kəʊˈɔːdɪneɪʃn ˈnʌmbə/ | número de coordenação |
| octahedral/ˌɒktəˈhiːdrəl/ | octaédrico |
| Absorption/əbˈsɔːpʃn/ | absorção |
Count what actually bonds
- A ligand 配体 donates an electron pair to a metal ion. Coordination number 配位数 counts donor atoms directly attached to that metal.
- Three bidentate en ligands have six donor atoms. A six-coordinate complex often has octahedral 八面体的 geometry.
Três ligantes bidentados não necessariamente dão número de coordenação três.
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Cada ligante contribui com dois átomos doadores, resultando em seis.
Keep atom and ion configurations separate
- Chromium is [Ar]3d⁵4s¹ and copper is [Ar]3d¹⁰4s¹. Remove 4s electrons before 3d to form positive ions.
- Cu²⁺ is d⁹ and meets the transition-element criterion. Zn²⁺ is d¹⁰; zinc does not meet that definition.
Qual íon possui subcamada d incompleta?
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Cobre(II) é d⁹, satisfazendo a condição de incompleto.
Solve charge before interpreting colour
- In [Cr(H₂O)₄Cl₂]⁺, neutral waters contribute zero and two chlorides contribute −2. Chromium is +3.
- Four water donors plus two chloride donors give coordination number six. Neither colour nor ligand count alone determines every structural detail.
For [Co(en)₃]³⁺, three neutral en ligands leave cobalt at +3 and give six donor atoms.
Encontre o estado de oxidação do cromo em [Cr(H₂O)₄Cl₂]⁺.
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x − 2 = +1, logo x = +3.
Explain colour using energy levels
- Ligands split d-orbital energy levels. Absorption 吸收 of suitable visible light promotes an electron between levels.
- Changing ligand, oxidation state or coordination number can change the gap. A d⁰ or d¹⁰ ion has no suitable d–d transition.
Quais duas alterações podem modificar o desdobramento dos orbitais d?
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O ambiente do ligante e o estado de oxidação afetam a lacuna de energia dos orbitais d.
Separate ammonia’s two roles
- A small amount of ammonia precipitates copper hydroxide by accepting protons from coordinated water.
- Excess ammonia replaces water ligands and dissolves the precipitate to give a deep blue solution. The copper remains +2.
Four-coordinate complexes may be tetrahedral or square planar; the same count can have different geometry.
Count donor pairs and coordination sites, track the metal oxidation state, and distinguish precipitation from ligand replacement before interpreting a colour change.
Amônia em excesso dá ao cobre(II) uma solução _____ profunda.
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O complexo amoniacal dissolvido é azul escuro, diferentemente do precipitado inicial azul claro.