STRUCTURE OF COORDINATION COMPLEXES IN CHEMISTRY

The coordination complexes, they are ions and molecules surrounding the "CENTRAL ATOM" are called ligands. The all ligands are generally bounding to the central atom by the coordinate covalent bond. Donating the electrons from a lone pair electron into an empty metal complex orbitals and to be coordinated to the atom. There are also including organic ligands. orɡanic compound alkenes have π bonds can coordinate to the empty metal complex orbitals.. For example, Ethene in the complex knows as a Zeise's salt,  K+[PtCl₃(C₂H₄)]-

Geometry :

In coordination chemistry, the structure is first described by it's the coordination number. The total number of the  bond between the the ligands attached to the central atom. Coordination atom ions larger numbers of bonds depend on the charge, size, and electron configuration of the metal ion and ligands.

            Normally metal atom ions  having more than one coordination number, typically complexes is dominated by interaction between s and p molecular orbitals of the ligands and d orbitals of metal ion. d and s, p orbitals of the metal can accommodate the 18 electrons.  average of  coordination number, certain metal is related to the electronic configuration of the metal ion. Especially number of the empty orbitals and ratio of the size of the ligands lead to coordination number. 

(Eg)

[Mo(CN)₈]⁴ small metals with larɡe liɡand lead to low coordination 

(Eg) Pt [P(CMe3)]₂. The due to larger size, lanthanides and actinides transition metal tend to having high coordination numbers.

      The many and different types of structures of ligand arrangement results from the coordination numbers. Most of the structure following the points on a shape pattern. The central atom in the middle of  polyhedron. where the corner of shape and location of the ligands. The orbital overlap between ligands and metal orbitals and ligand - ligand repulsion. It's lead to the certain regular geometries. The of the geometries observed. There are so many case which deviate from a regular geometrical shapes. Due to use of the ligand of different types of irregular bond lengths. 

1) Linear geometry for 2 - coordination number

2) Trigonal planner geometry for 3 coordination number

3) Tetrahedral geometry or Square planer for 4 coordination number

4) Trigonal bipyramidal geometry or Square pyramidal for 5 coordination number

5) Octahedral geometry name of orgthogonal or trigonal for 5 coordination number

6) Pentagonal bipyramidal geometry for 7 coordination number

7) Square shape or antiprismatic for 8 coordination number

8) Tri- caped trigonal prismatic geometry for 9 coordination number