Inorganic Chemistry: Core Concepts

• Inorganic chemistry studies the synthesis, properties, structures, and reactions of chemical compounds lacking carbon-hydrogen bonds.
• Organometallic compounds, featuring bonds between carbon and a metal, fall under inorganic chemistry.
• Inorganic chemistry includes all chemical compounds that are not organic.

Core Concepts

• Structure pertains to the arrangement of atoms in molecules and solids, exemplified by crystallography.
• Bonding describes how atoms are linked, including covalent, ionic, and metallic bonds.
• Reactivity explores inorganic compound chemical reactions.
• Synthesis focuses on creating new inorganic compounds.

Key Areas of Inorganic Chemistry

• Coordination Chemistry studies compounds formed between metal ions and ligands.
  • Ligands are molecules or ions bonding to a central metal atom.
  • Coordination complexes exhibit tetrahedral, octahedral, and square planar geometries.
  • Coordination complexes are relevant in catalysis, materials science, and biology.
• Organometallic Chemistry focuses on compounds with metal-carbon bonds.
  • Organometallic compounds are used in catalysis, organic synthesis, and materials science.
  • Common ligands include alkyls, carbonyls, and phosphines.
• Bioinorganic Chemistry examines metal roles in biological systems.
  • Metals are critical for the function of numerous enzymes like iron in hemoglobin.
  • Metal ions function in oxygen transport, electron transfer, and catalysis.
• Solid-State Chemistry focuses on the synthesis, structure, and properties of solid materials.
  • Solid-state chemistry applications include materials science, electronics, and energy storage.
  • Ceramics, semiconductors, and superconductors are examples of solid-state materials.

Important Classes of Inorganic Compounds

• Metal Complexes are compounds with a central metal atom/ion surrounded by ligands.
  • Examples are cisplatin, used in cancer treatment, and chlorophyll, involved in photosynthesis.
• Coordination Compounds include metal complexes, often having specific geometries and properties.
• Solid-State Materials are inorganic compounds forming extended networks or structures, such as zeolites.
  • Zeolites are used as catalysts and adsorbents.
• Acids and Bases have a broader scope in inorganic chemistry than in organic chemistry.
  • Examples include sulfuric acid (H2SO4) and ammonia (NH3).

Bonding Theories in Inorganic Chemistry

• Valence Bond Theory explains bonding as atomic orbital overlap, forming sigma (σ) and pi (π) bonds.
  • Hybridization describes the mixing of atomic orbitals.
• Molecular Orbital Theory describes bonding via molecular orbitals formed by combining atomic orbitals.
  • Bonding, antibonding, and non-bonding molecular orbitals exist.
• Crystal Field Theory explains the electronic structure of transition metal complexes based on electrostatic interactions between metal ions and ligands.
  • Crystal field splitting influences complex color and magnetic properties.
• Ligand Field Theory combines molecular orbital and crystal field theories for a more accurate depiction of bonding in transition metal complexes.

Reactions in Inorganic Chemistry

• Redox Reactions involve electron transfer between reactants.
  • Oxidation is electron loss, and reduction is electron gain.
• Acid-Base Reactions involve proton transfer (Brønsted-Lowry) or electron pair acceptance/donation (Lewis).
• Complexation Reactions involve coordination complex formation between metal ions and ligands.
• Precipitation Reactions involve insoluble solid formation from two or more soluble compounds reacting.

Characterization Techniques

• X-ray Crystallography determines atom arrangement in a solid by analyzing X-ray diffraction patterns.
• Nuclear Magnetic Resonance (NMR) Spectroscopy provides molecule structure and dynamics information by measuring nuclear spin interaction with a magnetic field.
• Electron Paramagnetic Resonance (EPR) Spectroscopy detects unpaired electrons in paramagnetic substances.
• UV-Vis Spectroscopy measures UV-Vis light absorption and transmission by a substance.
• Infrared (IR) Spectroscopy identifies molecule functional groups by measuring vibrational frequencies.
• Mass Spectrometry measures ion mass-to-charge ratio to determine compound elemental composition and structure.

Applications of Inorganic Chemistry

• Catalysis: many inorganic compounds catalyze industrial processes like Ziegler-Natta catalysts for polymerization.
• Materials Science: inorganic chemistry develops new materials with specific properties, such as semiconductors and superconductors.
• Medicine: inorganic compounds are used in medical imaging, drug delivery, and cancer treatment, for example, platinum-based drugs.
• Environmental Chemistry: inorganic chemistry helps understand and mitigate environmental pollution, such as heavy metal remediation.
• Energy: inorganic materials are used in solar cells, batteries, and fuel cells for energy conversion and storage.

Key Concepts in Coordination Chemistry

• Ligands are molecules/ions that bond to a central metal atom/ion through coordinate covalent bonds.
• Coordination Number is the number of ligands directly attached to the central metal atom/ion.
• Coordination Complexes are formed by coordinate covalent bonding of ligands to a central metal atom/ion.
• Isomerism means coordination complexes can exhibit structural and stereoisomerism.
  • Structural isomers are ionization, hydrate, and linkage isomers.
  • Stereoisomers include geometric (cis/trans, fac/mer) and optical isomers (enantiomers).

Crystal Field Theory (CFT)

• Crystal Field Splitting is the splitting of d-orbital energies in transition metal complexes by the ligand electrostatic field.
• Spectrochemical Series lists ligands ordered by their ability to cause crystal field splitting.
• High-Spin and Low-Spin Complexes are determined by the crystal field splitting magnitude relative to pairing energy.

Organometallic Chemistry Details

• Metal-Carbon Bonds are direct bonds between a metal and carbon atom, leading to unique reactivity.
• Ligands commonly found in organometallic chemistry include CO, PR3, alkenes, and cyclopentadienyl.
• Catalysis: Organometallic compounds are widely used as catalysts in various organic reactions.
  • Wilkinson's catalyst (RhCl(PPh3)3) facilitates hydrogenation.
  • Ziegler-Natta catalysts facilitate alkene polymerization.

Bioinorganic Chemistry Details

• Metalloproteins are proteins containing metal ions performing essential biological functions.
• Metalloprotein examples include:
  • Hemoglobin and myoglobin (oxygen transport and storage)
  • Cytochromes (electron transfer)
  • Nitrogenase (nitrogen fixation)
  • Carbonic anhydrase (CO2 hydration)
• Metal Homeostasis: Biological systems carefully regulate metal ion concentrations to prevent toxicity.