Extraction and Purification of Noble Metals

Organometallic Compounds and Hydrolysis

• Hydrolysis of organometallic compounds occurs via nucleophilic attack by water.
• Facilitating factors for hydrolysis include empty low-lying orbitals on the metal and metal-carbon bond polarity.
• The rate of hydrolysis increases with greater polarity of the M-C bond.

The 18-electron Rule (EAN)

• The 18-electron rule predicts the stability of d-block transition metal organometallic complexes.
• Transition metals have one s, three p, and five d orbitals, totaling nine orbitals that can accommodate 18 electrons.
• Stable compounds usually have a noble gas electron configuration.
• Complexes should have no overall charge; anionic ligands are also considered in electron counting.

CO-Metal Bonding Interactions

• σ-bond formation occurs through the overlap of empty hybrid orbitals on the metal with filled orbitals of carbon monoxide.
• π-bonding involves back donation from filled d orbitals/hybrid dp orbitals of the metal to antibonding π orbitals on CO.

Metal-Carbonyl Complexes

• Metal-carbonyls like nickel tetracarbonyl are important for industrial processes such as extraction and purification.
• Carbonyl complexes enable simple transfer to pure metal forms in processes like the Mond process.
• Metal carbonyls play roles in carbonylation reactions, impacting the production of aldehydes and other compounds.

Detection of Complex Formation

• Qualitative analysis utilizes color changes in complex formation for inorganic ion identification.
• Formation of colored precipitates with compounds like dimethyglyoxime aids in detecting specific metal ions.

Industrial Applications of Coordination Compounds

• Coordination compounds serve as catalysts, exemplified by rhodium complex used for alkene hydrogenation.
• Silver and gold electroplating is facilitated by metal cyanide complexes.
• In photography, silver complexes are used to fix developed films.

Structure and Bonding in Ferrocene

• Ferrocene consists of an iron center that is in the +2 oxidation state coordinated with cyclopentadienyl anions.
• Gains stability from an 18-electron configuration unique to its bonding structure.
• Features aromaticity due to the presence of 12 π-electrons shared with the metal.

Metals in Biology: Chlorophyll

• Chlorophyll contains Mg2+ as the central metal ion in a polycyclic, planar structure resembling protoporphyrin.
• The presence of a long phytol side chain attached to the chlorophyll structure aids in its functionality.
• Chlorophyll a and b, found in chloroplasts, work together to maximize light absorption efficiency in visible light.

Absorption Characteristics of Chlorophyll

• Chlorophylls exhibit high molar extinction coefficients, making them efficient at absorbing light essential for photosynthesis.
• Different absorption spectra of chlorophyll a and b allow for complementary light absorption, contributing to the green color of plants.

Role of Magnesium in Chlorophyll

• Magnesium is crucial for the stability of the chlorin ring; its absence leads to fluorescence, indicating loss of functionality in chlorophyll.

This quiz focuses on the processes involved in the extraction and purification of noble metals such as gold and silver from their ores. It also covers the role of complex formation in qualitative analysis, highlighting techniques for detecting metal complexes. Test your knowledge on chemical reactions and processes in inorganic chemistry.