Chapter 3 & 4 Notes

Transition Metals

Transition Metals

Elements in the d-block of the periodic table that have partially filled d orbitals.

Electronic Configurations

The arrangement of electrons in the d-block elements, specifically the filling of the 3d, 4d, and 5d orbitals.

Oxidation States

The maximum oxidation states of transition metals increase with group number, with group 3 having a maximum of +3 and group 7 having a maximum of +7.

Ligands & Complexes

Ligands are molecules or ions bonded directly to a transition metal, while transition-metal complexes are transition metal atoms bonded to several ions or molecules.

Notation

Square brackets are used to represent transition-metal complexes, with the cation indicated first and the ligand in the square brackets.

Categories of Ligands

Monodentate ligands have only one donor atom, bidentate ligands have two donor atoms, and chelate ligands have two or more donor atoms of the same ligand bound to the same metal center.

Isomerism

Different spatial arrangements of the same molecular formula in transition-metal complexes.

Coordination Numbers & Stereochemistry

Coordination number refers to the number of atoms directly bound to the metal center, while stereochemistry describes how the coordinated atoms are arranged in space.

Carbonyl Complexes

Complexes in which the ligands are carbon monoxide (CO) molecules.

Porphyrins

Ligands that coordinate to a metal center, such as Fe2+, and form octahedral geometry.

Hemoglobin

A protein that transports oxygen in the blood, with a tetrahedral shape and a heme group containing an Fe2+ porphyrin.

Crystal Field Theory

A theory that describes the electrostatic field of ligands around a transition metal ion and the splitting of d orbitals in octahedral complexes.

Orbital Energies

The energy levels of d orbitals in octahedral complexes, with t2g orbitals having lower energy and eg orbitals having higher energy.

Factors Affecting Δo

Factors that influence the energy separation between t2g and eg orbitals, including the oxidation state of the metal ion, the identity of the metal, the nature of the ligand, and the geometry of the complex.

Colours of Transition Metal Complexes

The colors observed in transition metal complexes are due to the absorption of light in the visible spectrum, with the absorbed colors being complementary to the observed colors.

Absorption Spectroscopy

A technique used to measure the colors and color intensities absorbed by a transition metal complex by passing light through it.

Magnetism in Transition Metal Complexes

Transition metal complexes with more unpaired electrons exhibit more paramagnetism, and the stability of the complex is influenced by the repulsion between paired electrons.