Advanced Inorganic Chemistry

Study Notes

Inorganic Chemistry (Fourth Edition) by James E. Huheey, Ellen A. Keiter, Richard L. Keiter and Okhil K. Medhi
Inorganic Chemistry (Third Edition) by Gary L. Miessler and Donald A. Tarr
Basic Organometallic Chemistry by BD Gupta and AJ Elias
Inorganic Chemistry by Keith F. Purcell and John C. Kotz (India Edition)

Organometallic chemistry is the study of chemical compounds containing at least one chemical bond between a carbon atom of an organic molecule and a metal. (M-C bond)
Organometallic compounds include all compounds containing a bond between a metal atom and a carbon atom of an organyl group.
Structures forming organometallic compounds include: alkali metals, alkali earth metals, transition metals, post-transition metals, lanthanides, actinides, semimetals, boron, silicon, arsenic, and selenium.
Examples of organometallic compounds include: Gilman reagents, Grignard reagents, tetracarbonyl nickel, ferrocene, n-butyl lithium, diethyl zinc, tributyltin hydride, triethylborane and trimethylaluminium.
Methylcobalamin (a form of vitamin B12) is a naturally occurring organometallic complex which contains a cobalt-methyl bond.

Electron rich central metal (low oxidation state) and ligands which are good π-acceptors, generally adhere to the 18 electron rule.
The 18 electron rule is useful for predicting whether a complex will be stable and/or whether metal-metal bonds are present.
Two methods of determining electron counts are: neutral atom count, oxidation state count.
The 18 electron rule is not always strictly followed.
Complexes with fewer than 18 electrons can be stable in some situations.

Complexes tend to follow the 18 electron rule; if they have large Δo, making occupation of e* unfavourable, including 4d and 5d series elements, they will form 18 electron complexes, not more than 18 electrons.
For 3d series metals, Δo is small, so occupation of e* is possible in some cases.
Examples of known stable complexes include [Co(H2O)6]2+, [Ni(en)3]2+, [Cu(NH3)6]2+ and [Zn(NH3)6]2+.

Organometallic catalysts can decrease the temperature and pressure needed in chemical processes.
Organometallic catalysts have a 25 billion dollar industry.
Effective atomic number (EAN) = Z – ON + 2(CN)
Z = atomic number
ON = Oxidation number
CN = Coordination number
An alternative is the 18 Electron Rule.

Infrared Spectroscopy is a useful tool for characterizing metal carbonyl complexes.
Terminal CO stretching vibrations occur in the 2120 - 1850 cm⁻¹ range.
Bridging CO stretching vibrations occur in the 1850 - 1720 cm⁻¹ range.

Square planar complexes are exceptions to the 18 electron rule.
Some complexes follow a 16 electron rule.
Different ligands have different electron donating and accepting properties.
Ligand donating and accepting properties impact the stability and properties of the metal complexes, influencing the number of electrons transferred and the resulting electronic configuration of the complexes.
Important Organometallic Compounds, such as [PtCl₄]⁻², HMn(CO)₅, [Mn(CO)₅]⁻, [V(CO)₆]⁻, and Fe₃(CO)₁₂ are discussed.