Metal Carbonyls: Structure and Bonding

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Questions and Answers

What is the bond length of the Ni-C bond in the nickel carbonyl molecule?

1.128 Å

1.52 Å (correct)

1.15 Å

1.82 Å

How does the bond length of the C-O bond in nickel carbonyl compare to that in the CO molecule?

It varies based on the hybridization state.

It is equal to the C-O bond length in CO.

It is longer than the C-O bond length in CO. (correct)

It is shorter than the C-O bond length in CO.

What hybridization state is found in the nickel carbonyl molecule?

dsp3

sp3 (correct)

sp2

In the context of the provided information, which statement about the bonding of the oxygen atom is correct?

It is simply bonded to the carbon atom. Signup and view all the answers

What is the electron configuration of the nickel atom cited in the information?

[Ar] 3d8 4s2 Signup and view all the answers

What is the electronic configuration of the CO molecule indicating about its structure?

It contains a lone pair of electrons on both carbon and oxygen. Signup and view all the answers

Which of the following statements about mononuclear carbonyls is true?

They have the general formula M(CO)n. Signup and view all the answers

What is the molecular shape of nickel tetracarbonyl (Ni(CO)4)?

Tetrahedral Signup and view all the answers

Which metal carbonyl has a trigonal bipyramidal structure?

Fe(CO)5 Signup and view all the answers

What does the term 'zero oxidation state' imply for metal atoms in metal carbonyls?

The metal atom has a complete electron shell. Signup and view all the answers

What type of hybridization occurs in the Ni atom of the Ni(CO)4 molecule?

sp³ hybridization Signup and view all the answers

What role does the carbonyl group play in forming metal carbonyls?

It serves as an electron donor. Signup and view all the answers

Which orbitals are involved in the ground state of a nickel atom?

3d and 4s Signup and view all the answers

What is the significance of the new orbital diagram for Ni(CO)4?

It shows the efficiency of pi backbonding. Signup and view all the answers

What is the coordination number of nickel in Ni(CO)4?

4 Signup and view all the answers

Which element typically forms coordination compounds with carbonyl groups?

Nickel Signup and view all the answers

Which of the following statements is true about metal carbonyls?

They consist of a metal and a carbonyl group. Signup and view all the answers

Which orbital is not occupied in the new orbital configuration of Ni(CO)4?

5s Signup and view all the answers

What is the general formula for poly-nuclear carbonyls?

M(CO)n Signup and view all the answers

What shape does the Ni(CO) molecule exhibit according to X-ray diffraction studies?

Tetrahedral Signup and view all the answers

Which metal complex is exemplified with a linear arrangement in the content?

Cr1cn1 Signup and view all the answers

What key characteristic is associated with poly-nuclear carbonyl complexes?

They can contain more than one carbonyl group per metal. Signup and view all the answers

What is the coordination number of nickel in Ni(CO)2?

4 Signup and view all the answers

Which of the following is a plausible structure for a mono-nuclear carbonyl complex?

Ni(CO)4 Signup and view all the answers

In terms of molecular geometry, what distinguishes tetrahedral complexes from linear ones?

Linear complexes are formed by two or more coordinate bonds. Signup and view all the answers

What type of studies are particularly useful to determine the molecular structure of carbonyl complexes?

X-ray diffraction studies Signup and view all the answers

Study Notes

Metal Carbonyls

Metal Carbonyls are coordination compounds formed between an electron donor carbonyl group (CO) and a metal atom
The bond structure of metal carbonyls is supported by the donation of the lone pair of electrons in the CO group to the vacant orbitals of the metal atom
The CO group is bound to the metal atom by a simple sigma bond, which is also known as a coordinate bond
The CO groups are replaceable by other electron donor groups such as halides, phosphines, or alkenes
The bond lengths in a Ni(CO)4 molecule indicate that:
- The Ni-C bond length is 1.80 Å, which is shorter than the usual Ni-C single bond length (1.82 Å) found in other compounds
- The C-O bond length is 1.15 Å, which is longer than the C-O bond length in the CO molecule (1.128 Å)
Raman spectral studies have shown that the Oxygen atom in the CO group, is simply bonded to the carbon atom
Nickel in Ni(CO)4 should be sp3 hybridized. This means it has four hybrid orbitals, which allow it to make four bonds.
Nickel in its ground state has the electronic configuration 2s2 2p6 3s2 3p6 3d8 4s2
In Ni(CO)4, the 4s and three 4p orbitals hybridize to form four sp3 orbitals
The four sp3 orbitals then form sigma bonds with the four CO molecules.
Metal carbonyls are formed mainly by transition metals.
The electronic configuration of CO indicates that it has a lone pair of electrons on both the carbon and oxygen atoms
These electrons are used to form coordinate bonds with the transition metal
The electron pair used in the M-CO bond comes solely from the CO molecule
According to the classification of metal carbonyls proposed by Hieber, carbonyls are classified into two groups:
- Mononuclear Carbonyls:
  - These carbonyls have the general formula M(CO)x where "M" is the metal atom, and "x" is a number corresponding to the number of CO groups.
  - Examples of mononuclear carbonyls include Ni(CO)4, Fe(CO)5, and Cr(CO)6.
  - Mononuclear carbonyls are generally formed by metals having even atomic numbers
  - They are readily soluble in organic solvents
  - They are more volatile than other carbonyls
  - Mononuclear carbonyls can have different shapes, depending on the number of CO groups:
    - Tetrahedral, like Ni(CO)4
    - Trigonal bipyramidal, like Fe(CO)5 and Os(CO)5
    - Octahedral, like Cr(CO)6
- Polynuclear Carbonyls:
  - These carbonyls have the general formula Mx(CO)y where "M" is the metal atom and "x" and "y" are integers
  - Polynuclear carbonyls contain more than one metal atom in the molecule.
  - Examples of polynuclear carbonyls include [Co2(CO)8] and [Fe3(CO)12]
  - Polynuclear carbonyls are generally formed by metals having odd atomic numbers.
X-ray diffraction studies have shown that Ni(CO)4 has a tetrahedral shape
This tetrahedral shape has four CO groups attached to the central Nickel atom
The text states that Ni(CO)4 is classified as a mononuclear carbonyl, but it can also be classified as a polynuclear carbonyl because it contains a single nickel atom as the metal center, and it is comprised of more than one coordinated carbonyl group

The Chemistry of Ni(CO)4

Ni(CO)4 is a volatile liquid that can form a tetrahedral shape.
It is crucial to emphasize that the CO groups donate their electrons, making the nickel atom effectively neutral
This is a result of the coordination of carbon in the CO groups to the nickel atom
The metal atom in carbonyls is said to be in the zero oxidation state
CO molecules are considered neutral ligands in metal carbonyls.
Ni(CO)4 has important industrial applications, such as the purification of Nickel.
Ni(CO)4 is also a dangerous compound and must be handled with caution.

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Description

This quiz explores the fundamental concepts of metal carbonyls, coordination compounds formed between carbonyl groups and metal atoms. It covers the bonding structure, hybridization, and variations in bond lengths in a typical metal carbonyl compound like Ni(CO)4.