info@urfaculty.com

www.urfaculty.com

Govt. Job/ Sarkari Naukri, NEET, CAT, Bank Exam & Study materials

Thursday, 23 February 2017

Co-ordination Compounds - II


Charge on the complex ion:
  • The charge on the complex ion is equal to the algebraic sum of the charges on all the ligands coordinated to the central metal ion.
Denticity:
  • The number of ligating (linking) atoms present in ligand is called denticity.
Unidentate ligands:
  • The ligands whose only one donor atom is bonded to metal atom are called unidentate ligands.
  • Examples: H 2O, NH3, CO, CN-
Didentate ligands:
  • The ligands which contain two donor atoms or ions through which they are bonded to the metal ion.
  • Examples: Ethylene diamine (H2NCH2CH2NH2) has two nitrogen atoms, oxalate ion has two oxygen atoms which can bind with the metal atom.
Polydentate ligand:
  • When several donor atoms are present in a single ligand, the ligand is called polydentate ligand.
  • Examples:  In  N(CH2CH2NH2)3,  the  ligand  is  said  to  be  polydentate  and
  • Ethylenediaminetetraacetate ion (EDTA4-) is an important hexadentate ligand. It can bind through two nitrogen and four oxygen atoms to a central metal ion.
Chelate:
  • An inorganic metal complex in which there is a close ring of atoms caused by attachment of a ligand to a metal atom at two points.
  • An example is the complex ion formed between ethylene diamine and cupric ion, [Cu(NH2CH2NH2)2]2+.
Ambidentate ligand:
  • Ligands which can ligate (link) through two different atoms present in it are called ambidentate ligand.
  • Example: NO2-and SCN-. Here, NO2- can link through N as well as O while SCN- can link through S as well as N atom.
Werner’s coordination theory:
Werner was able to explain the nature of bonding in complexes.
The postulates of Werner’s theory are:
  • Metal shows two different kinds of valencies: primary valence and secondary valence.
  • The ions/ groups bound by secondary linkages to the metal have characteristic spatial arrangements corresponding to different coordination numbers.
  • The most common geometrical shapes in coordination compounds are octahedral, square planar and tetrahedral.
Primary valence
  • This valence is normally ionisable.
  • It is equal to positive charge on central metal atom.
  • These valencies are satisfied by negatively charged ions.
  • Example: In CrCl3, the primary valency is three. It is equal to oxidation state of central metal ion.
Secondary valence
  • This valence is non – ionisable.
  • The secondary valency equals the number of ligand atoms coordinated to the metal. It is also called coordination number of the metal.
  • It is commonly satisfied by neutral and negatively charged, sometimes by positively charged ligands.
Oxidation number of central atom:
  • The oxidation number of the central atom in a complex is defined as the charge it would carry if all the ligands are removed along with the electron pairs that are shared with the central atom.
Homoleptic complexes:
  • Those complexes in which metal or ion is coordinate bonded to only one kind of donor atoms. For example: [Co(NH3)6]3+
Heteroleptic complexes:
  • Those complexes in which metal or ion is coordinate bonded to more than one kind of donor atoms. For example: [CoCl2(NH3)4]+, [Co(NH3)5Br]2+
Click here to view complete Chemistry Free Study Materials and Notes for NEET Preparation

Click here to view complete Physics Free Study Materials and Notes for NEET Preparation

Click here to view complete Biology Free Study Materials and Notes for NEET Preparation

Click here to take NEET online practice tests by UrFaculty.com

No comments:
Write comments

Hey, we've just updated our test package. Check'it out here - https://goo.gl/r7FuPT
Join Youth Apps