Introduction to d-Metal Organometallic Chemistry

These flashcards cover key concepts from the lecture notes on organometallic chemistry, focusing on the 18 electron rule, ligand interactions, and reaction mechanisms.

What is the 18 electron rule in organometallic chemistry?

The 18 electron rule states that a stable organometallic complex typically has 18 valence electrons, achieved through the combination of metal d electrons and the electrons donated by ligands.

What was the significance of Zeise's salt in organometallic chemistry?

Zeise's salt, the first organometallic compound isolated in 1827, marked the beginning of organometallic chemistry and was later confirmed to contain ethene.

Which method is used for counting electrons in organometallic complexes?

The neutral ligand method assigns electron counts based on the type of ligands (L=2e donors, X=1e donors) and adjusts for the metal's charge.

How does carbon monoxide (CO) interact with transition metals?

CO acts as a ligand by donating electrons through σ-bonding and accepting electrons via p-backbonding, which stabilizes low oxidation state transition metals.

What can the stretching frequency of CO in IR spectroscopy indicate?

The stretching frequency of CO in IR spectroscopy can indicate the strength of the metal-carbon bond; stronger M-CO bonds correspond to lower stretching frequencies.

What is the role of phosphines in organometallic chemistry?

Phosphines are important ligands that can donate 2 electrons and help form stable complexes, often tuned by their size and electronic properties.

What occurs during the oxidative addition reaction?

In oxidative addition, a bond between two electronegative atoms (X-Y) adds to the metal center, increasing its oxidation state and coordination number.

How do cyclopentadienyl ligands behave in organometallic complexes?

Cyclopentadienyl ligands can act as h1, h3, or h5 donors, participating in σ-bonding and influencing the stability and reactivity of the complex.

What distinguishes σ-donor ligands from π-acceptor ligands?

σ-donor ligands donate electron pairs to the metal, whereas π-acceptor ligands accept electron density from the metal's d orbitals, enhancing the interaction.

What are the key differences between associative and dissociative ligand substitution reactions?

In associative pathways, a new ligand coordinates before the old one leaves, while in dissociative pathways, the old ligand departs before a new ligand attaches.

What is the relevance of the DCD model concerning alkenes in organometallic chemistry?

The Dewar-Chatt-Duncanson model explains how alkenes interact with metals, highlighting the balance between σ-donation and π-backbonding in these complexes.

What is the primary feature of cyclooctatetraene (COT) as a ligand?

Cyclooctatetraene is too large for effective bonding to d-block metals under the 18 electron rule but can act as an h4 ligand in f-block complexes.

What does the term ‘non-classical hydrides’ refer to in organometallic chemistry?

Non-classical hydrides are dihydrogen complexes that display unique bonding characteristics and may involve backbonding with hydrogen atoms.

What can be inferred from the type of ligands coordinating to a metal center?

The nature and type of ligands significantly influence the electronic properties, stability, and reactivity of the metal complex.