Coordination Chemistry Lecture Notes Review

A collection of vocabulary flashcards covering the fundamental concepts, theories, and nomenclature of coordination chemistry as presented in the lecture transcript.

Secondary Valency

In Werner's theory, this refers to the non-ionisable valency of a metal which is satisfied by neutral molecules or negative ions; it is equal to the coordination number and determines the geometry of the complex.

Primary Valency

In Werner's theory, these are ionisable linkages typically satisfied by negative ions, corresponds to the oxidation state of the metal, and are non-directional.

Ambidentate Ligand

A ligand that possesses two different donor atoms and can coordinate to the central metal ion through either of the two atoms, such as $\text{NO}_2^-$ or $\text{SCN}^-$.

Crystal Field Splitting Energy

The energy difference between the split sets of d-orbitals (such as $t_{2g}$ and $e_g$ in octahedral fields) resulting from the electrostatic field of the surrounding ligands.

Linkage Isomerism

A type of isomerism that occurs when an ambidentate ligand is bonded to the central metal atom through different donor atoms.

Ionization Isomers

Compounds that have the same molecular formula but produce different ions in solution because the ligand and the counter ion outside the coordination sphere exchange places.

Coordination Isomers

A form of isomerism in compounds containing both complex cationic and anionic species, resulting from the interchange of ligands between the two metal centers.

Chelate Effect

The enhanced stability associated with complexes containing polydentate (chelating) ligands compared to similar complexes with only unidentate ligands.

Homoleptic Complex

A coordination compound in which the central metal atom or ion is bound to only one kind of donor group, such as $[Cr(H_2O)_6]Cl_3$.

Heteroleptic Complex

A coordination compound in which the central metal atom or ion is bound to more than one kind of donor group, such as $[Co(NH_3)_4Cl_2]^+$.

Spectrochemical Series

A list of ligands arranged in increasing order of their crystal field splitting power ($\Delta$), used to distinguish between weak field and strong field ligands.

Inner Orbital Complex

A coordination compound formed using $(n-1)d$ orbitals for hybridization (also known as a low spin complex), typically occurring with strong field ligands.

Outer Orbital Complex

A coordination compound formed using $nd$ orbitals for hybridization (also known as a high spin complex), typically occurring with weak field ligands.

Coordination Number

The total number of ligand donor atoms directly bonded to the central metal ion in a complex.

Double Salt

A substance that exists only in the solid state and dissociates into its constituent simple ions completely when dissolved in water, unlike a coordination complex which retains its identity.

Bidentate Ligand

A ligand that has two donor atoms available to bind to a single metal ion, such as ethane-1,2-diamine (en) or oxalate ion ($C_2O_4^{2-}$).

Polydentate Ligand

A ligand that can bind to a metal ion through multiple donor atoms; an example is $\text{EDTA}$, which can bind via six donor atoms.

Wilkinson Catalyst

A coordination compound used in chemical processes, identified in the notes for its specific formula and utility (typically refers to $[RhCl(PPh_3)_3]$ used for hydrogenation).

Hydrate Isomerism

A form of isomerism where water molecules can act either as ligands inside the coordination sphere or as water of crystallization outside the sphere.