Modern Chemistry & Applications

Organometallic Chemistry of d Block Metals and Reactions of their Complexes

Bilal Mohammed^* Department of Chemical Sciences, University of Peshawar, Khyber Pakhtunkhwa, Pakistan
^*Correspondence: Bilal Mohammed, Department of Chemical Sciences, University of Peshawar, Khyber Pakhtunkhwa, Pakistan, Email:

Received: 30-Sep-2022, Manuscript No. MCA-22-18602; Editor assigned: 03-Oct-2022, Pre QC No. MCA-22-18602 (PQ); Reviewed: 17-Oct-2022, QC No. MCA-22-18602; Revised: 24-Oct-2022, Manuscript No. MCA-22-18602 (R); Published: 31-Oct-2022, DOI: 10.35248/2329-6798.22.10.380

Description

Organometallic chemistry of transition metals is relatively new. Although their bonds and structures were unknown in the 19th century, after that the work of W. Hieber on metal carbonyl compounds was important in his 1930s, but the results of these studies were not supported by structural analysis techniques available at the time and they was under developed and also limited..

The discovery of ferrocene Fe (C5H5)2 in 1951 was a breakthrough for this field of chemistry. The very unique binding mode of this complex was revealed by single-crystal X-ray structural analysis, NMR spectroscopy, infrared spectroscopy, etc., and served as a starting point for the subsequent development of this field. It was an important finding of era. Ferrocene has very high thermal stability and despite the popular belief that transition metal-carbon bonds are highly labile. It was also revealed that this compound has a sandwich structure in which the five carbon atoms of the cyclopentadienyl group are simultaneously bonded to the central metallic iron.

Hydrocarbon complexes

Organometallic compounds are those having metal-carbon bonds in between one and eight carbon atoms. Hapticity is known as the number of atoms in a ligand that having the direct coordinative interaction with the metal and number which is added to η.

For example, In a π allyl complexes if an allyl group CH2=CHCH2- is bonded to an metal via carbon atom, When the double bond delocalizes, three carbon atoms bond to the metal simultaneously as a 3-electron ligand.

Phosphine complexes

Tertiary phosphines are used as stabilization ligands in transition of metal complexes and they are coordinate towards the metals in relatively high to low oxidation state. These complexes are frequently used as an carbonyl or cyclopentadienyl ligands in chemistry of organometallic complexes.

Phosphine complexes are Lewis bases and they coordinate to the metal by using the lone pair on phosphorus and show π-acidity while carrying the X substituents including Ph, Cl, or F which having strong electron accepting properties.

Small molecule complexes

2 or 3 atomic molecules (H₂, N₂, CO, NO, CO₂, NO₂, and H₂O, SO₂) are called small molecules and chemistry of their complexes is used not only for basic inorganic chemistry but also for the Catalytic chemistry, Industrial chemistry, and Environmental chemistry.

Metal-metal bonds

The formation of an coordinate bond between ligands and central metal ion proposed by A. Werner and it was basis for the complex development. Most of the di nuclear or poly nuclear complexes that contain more than 2 metals in a complex, it was sufficient to take into consideration, only when having the bonds between the ligands and metal.

Metal cluster compounds

Structures of an newly prepared polynuclear complexes which contain 2 or more metals which was very difficult to complex. In single crystal X-ray structural analysis, our understanding of the chemistry of polynuclear complexes is progressing quickly. Metalcluster complexes are polynuclear complexes built by 3 or more transition-metal atoms having bonds between the metals which coordinated by ligands to form an polyhedral frames such as in shapes of triangle, regular tetrahedron, regular octahedron and an icosahedron. If there is no strong bond between 2 metals, as long as there is some other interaction may present, they can be included as an cluster compounds.

Reactions of complexes

The reactions of complexes are classified into Ligand substitution reactions and Redox reactions of the central metal ion.

Ligand substitution reactions

These complex reactions are important for preparation of various kinds of derivatives. These reactions are studied to understand their stereochemistry and to gain practical rates of substitution reactions. Comparing to other types of chemical reactions these reactions requires an understanding of both equilibrium and reaction rates.

Redox reactions

Oxidation number of central metal in a transition-metal compound can vary in a few steps from low to high. Oxidation state of a compound is changeable by using redox reactions.

Conclusion

The industrial importance of organometallic compounds of the transition metal increased with the discovery of olefin polymerization catalysts (Ziegler catalysts), homogeneous hydrogenation catalysts (Wilkinson catalysts), and the development of catalysts for the binary metal carbonyl compounds which consists of only CO ligands and metal are prepared by direct reaction of an powder (highly reactive metal and carbon monoxide) or (by the reduction of an metal salt to zero valance by reaction followed with high-pressure carbon monoxide).