Introduction to Organometallic Chemistry
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Questions and Answers

What is the general charge on a metal when it forms a complex with ligands?

Generally, metals are electropositive, and ligands are electron donors. So, the metal will have a positive charge in the complex.

The first reported organometallic (OM) complex was [Pt(NH3)4]^[2+], which is also known as ______ .

Zeise's salt

Which of the following are considered coordination numbers?

  • 8 (correct)
  • 2 (correct)
  • 4 (correct)
  • 6 (correct)

    • Transition metals are often found in their reduced metallic form, but they can also form covalent bonds with electron donors to form complexes.

    <p>True (A)</p> Signup and view all the answers

    What are some common geometries observed in metal complexes, and how are they determined?

    <p>Common geometries include linear, trigonal planar, T-shaped, tetrahedral, square planar, see-saw, trigonal bipyramidal, square pyramidal, and pentagonal bipyramidal. These geometries are often determined by steric factors, the size of ligands, and the electronic interactions involving the ligand electron pairs and the metal d orbitals.</p> Signup and view all the answers

    Match the following geometries with their corresponding descriptions:

    <p>Linear = Two ligands arrange themselves on opposite sides of the metal center Trigonal Planar = Three ligands are arranged at 120 degrees around the metal center Tetrahedral = Four ligands are positioned in a tetrahedron around the metal center Square Planar = Four ligands are placed at 90 degrees around the metal center Trigonal Bipyramidal = A combination of a triangular base and two apical ligands Square Pyramidal = A square base with one ligand positioned above the center Pentagonal Bipyramidal = Two apical ligands are placed above and below a pentagonal base</p> Signup and view all the answers

    The ______ theory is a model used to explain the bonding and electronic structure of metal complexes.

    <p>Crystal Field Theory (CFT)</p> Signup and view all the answers

    The geometry of metal complexes can be influenced by electronic considerations such as ligand field stabilization energy (LFSE).

    <p>True (A)</p> Signup and view all the answers

    Commonly, chemists refer to metals simply by their ______-count.

    <p>d</p> Signup and view all the answers

    A metal complex with an odd number of d-electrons will be diamagnetic.

    <p>False (B)</p> Signup and view all the answers

    Which of the following is NOT an example of an L-type ligand?

    <p>Cl (D)</p> Signup and view all the answers

    Match the following ligands with their corresponding type:

    <p>PR3 = L-type Cl = X -type CN = X-type CO = L-type en = L-type OR' = X-type</p> Signup and view all the answers

    What is the main difference between L-type and X-type ligands?

    <p>L-type ligands are neutral when they dissociate from the metal, while X-type ligands carry a negative charge.</p> Signup and view all the answers

    Which of the following ligands is considered a strong-field ligand, according to the spectrochemical series?

    <p>Cyanide (CN-) (C)</p> Signup and view all the answers

    Which of the following is NOT a common situation where d-count knowledge is useful?

    <p>Determining the oxidation state of the metal (A)</p> Signup and view all the answers

    The spectrochemical series primarily focuses on the σ donor strength of ligands.

    <p>False (B)</p> Signup and view all the answers

    A d^8 metal complex will always have a square planar geometry.

    <p>False (B)</p> Signup and view all the answers

    In the ionic method of electron counting, ligands contribute ______ electrons each.

    <p>2</p> Signup and view all the answers

    What is the main reason behind the increased stability of transition metal complexes with 18 valence electrons?

    <p>Complexes with 18 valence electrons achieve a stable electronic configuration by filling all the bonding and non-bonding orbitals, while avoiding the filling of antibonding orbitals.</p> Signup and view all the answers

    The ______ of a metal complex refers to the number of valence electrons surrounding the central metal atom.

    <p>electron count</p> Signup and view all the answers

    What is the electron count for the complex $[Ru(p-(ym)Cl_4]2$?

    <p>18 (A)</p> Signup and view all the answers

    Match the following terms with their respective descriptions:

    <p>Spectrochemical series = Arranges ligands based on their ability to influence the energy gap between d orbitals π-backbonding = The donation of electron density from a filled metal d orbital into an empty ligand π* orbital 18-electron rule = A guideline for predicting the stability of transition metal complexes based on their electron count Oxidation state = The charge left on the metal after all ligands are removed in their closed-shell configuration</p> Signup and view all the answers

    The complex [PdCl4]^2- has a square planar geometry based on its 16-electron count.

    <p>True (A)</p> Signup and view all the answers

    What is the electron count for a metal complex with 4 X-type ligands and 2 L-type ligands? Explain your reasoning.

    <p>The electron count is 16. Each X-type ligand contributes one electron, so 4 X-type ligands contribute 4 electrons. Each L-type ligand contributes two electrons, so 2 L-type ligands contribute 4 electrons. The total is 8 electrons from the ligands. Adding the 8 electrons from the metal atom (assuming it's in a neutral oxidation state), the total electron count for the complex is 16.</p> Signup and view all the answers

    What is the oxidation state of the metal in the complex [Fe(CO)6]2−?

    <p>2+</p> Signup and view all the answers

    The electron counting method is only used for determining the stability of complexes.

    <p>False (B)</p> Signup and view all the answers

    The complex [Cr(CO)6] has a total electron count of ______ electrons.

    <p>18</p> Signup and view all the answers

    Match the following ligands with their electron donation count:

    <p>Cl = 1 electron CO = 2 electrons PPh3 = 2 electrons</p> Signup and view all the answers

    Which of the following statements is TRUE regarding the 18-electron rule?

    <p>The 18-electron rule is a useful guideline for predicting the stability of transition metal complexes. (D)</p> Signup and view all the answers

    Which of the following best describes the purpose of bridging ligands in coordination chemistry?

    <p>To stabilize the molecule by filling the metal orbitals (D)</p> Signup and view all the answers

    The 3-center, 2-electron bond is a concept that explains the bonding in molecules like "Et3P-Ir-H-Ir-Pets" and "Ph3P OC H Rh Rh H Co -PPh3", where electrons are shared between multiple atoms.

    <p>True (A)</p> Signup and view all the answers

    What is the primary reason behind the formation of bridging ligands, as described in the text?

    <p>Bridging ligands often form to satisfy the electron deficiency in metal orbitals, leading to greater stability and filling the metal's electron requirement.</p> Signup and view all the answers

    The number of contiguous conjugated atoms of a ligand bound to a metal is referred to as its ______.

    <p>hapticity</p> Signup and view all the answers

    Match the following terms with their corresponding definitions.

    <p>CI = A chemical symbol for the element chlorine Ru = A chemical symbol for the element ruthenium L-type = A ligand that donates two electrons to a metal x-type = A ligand that donates one electron to a metal η^3 = A type of bonding where a ligand binds to a metal through 3 contiguous atoms</p> Signup and view all the answers

    Which of the following statements is TRUE regarding the concept of "hapticity"?

    <p>It refers to the number of atoms in a ligand that are bonded to a metal. (A)</p> Signup and view all the answers

    The compound "Et3P-H-Ir-PEt3" is a good example of a molecule that demonstrates a 3-center, 2-electron bond.

    <p>True (A)</p> Signup and view all the answers

    What is the electron count for each Rh atom in the compound "Ph3P OC H Rh Rh H Co -PPh3"?

    <p>16e⁻</p> Signup and view all the answers

    Which of the following best describes ligands that are 2LX?

    <p>$PR_3$ (A), $R_2N$ (C), $PR_2$ (D)</p> Signup and view all the answers

    Metals typically form M-M bonds frequently in coordination complexes.

    <p>False (B)</p> Signup and view all the answers

    What is the formula used to determine the number of M-M bonds in a metal complex?

    <p>#MM=(18•M-valence e total)/2</p> Signup and view all the answers

    The bonding of carbonyls involves both __________ donation and __________ back donation.

    <p>σ, πL</p> Signup and view all the answers

    Match the following terms with their descriptions:

    <p>Carbonyl = CO ligand known as the silent killer σ-donation = From HOMO of CO to empty orbital on metal πL-back donation = From filled orbital back to CO 18e rule = Assumption for determining metal-metal bonds</p> Signup and view all the answers

    Study Notes

    Organometallic Chemistry Introduction

    • Organometallic chemistry is the chemistry of compounds containing a metal-carbon (M-C) bond.
    • It involves studying the bonding, properties, and reactivity of these compounds.

    Electronegativity Differences

    • Electronegativity values of atoms affect the polarity of bonds.
    • For example, carbon is less electronegative than chlorine, but more electronegative than magnesium in a C-Cl or a C-Mg bond. This inverse polarity is important.

    Importance of Organometallic Chemistry

    • Organometallic compounds are important in chemical transformations.
    • C-C bond formation from two electrophilic components is a key result shown.
    • This is significant in synthetic chemistry.

    Reactions involving Organometallics

    • Grignard reagents react with various molecules.
    • Alkyl lithiums also participate in similar reactions.

    Transition Metals

    • Not all transition metals behave the same (TM)
    • All TM are elements in the d-block.
    • In their metallic form, most transition metals exist as solids.
    • Transition metals can also form complexes with organic and inorganic molecules.

    Ligands and Bonding in Complexes

    • Ligands (molecules or ions) act as electron donors to a metal.
    • Ligand bonding in TM complexes is influenced by steric factors and non-bonding electrons.
    • Common geometries in metal complexes include linear, trigonal planar, T-shaped, trigonal pyramidal, square planar, and square pyramidal.

    Coordination Number

    • Coordination number is how many ligands are coordinated to the same metal.
    • The geometry of a metal complex is a result of steric factors of ligands.

    Relevant Orbitals

    • s, p, and d orbitals of metals interact with ligands.
    • Ligand orbitals and bonding lead to Molecular orbital (MO) diagrams
    • Coordination compounds can have a wide variety of geometries.

    18-Electron Rule

    • The 18-electron rule is a common guideline for predicting the stability of transition metal complexes.
    • In general, transition metal complexes with 18 valence electrons are stable.
    • Complexes with fewer than 18 valence electrons may be reactive.
    • In some cases, complexes with 16 valence electrons are also stable.

    Metal-Ligand Bonding

    • Organic chemistry bonding (σ-bonding) is similar to how metal ligands bond.
    • The same basic concept applies in organic and organometallic chemistry.
    • Ligands can participate in o-bonding with the metal.
      • Ligands can participate in π-bonding with the metal.

    Ligand Types

    • Ligands can act as electron donors.
    • The strength of bonding depends on the type of ligand and the metal.
    • The geometry of ligands can affect the stability of a complex.
    • Ligands are important in organometallic chemistry, influencing the reactivity and properties of complexes.

    Oxidation States

    • Metal oxidation states influence reactivity.
    • Some metals readily exist in high oxidation states.
    • A metal's oxidation state largely dictates its reactivity.

    Electron Counting

    • In the process of electron counting, metals, their electron configuration, and ligand types are used to determine the valence electron count.
    • Understanding these factors is helpful to predict the magnetic properties and geometries of a complex.

    Coordination Compounds Characteristics

    • Coordination number is the number of ligands bonded to a metal ion.
    • Oxidation state is the charge of a metal ion once ligands are removed.
    • Overall charge is the metal centre and ligands combined.

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    Organometallic Chemistry Lecture Notes 2025 PDF

    Description

    Explore the basics of organometallic chemistry, focusing on metal-carbon bonds and their significance in chemical reactivity and synthesis. Learn about electronegativity differences and the role of transition metals in these reactions. This quiz is essential for understanding the foundation of organometallic compounds and their applications.

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