7 Facts On Cu[(nh3)4] 2+ Lewis Structure, Characteristics

Cu[(nh3)4] 2+ Lewis structure and 7 facts on Cu[(NH3)4]2+ ion that is named as Tetraamine copper ion in chemistry would be described in this article. The facts would be revealed through the sketch of Lewis structure of this complex compound.

The facts that would be described illustrating internal characteristics of the compound are:

Cu[(NH3)4]2+ Name

A complex compound is always need to hold a specific name which is defined by applying the rules given by IUPAC (International Union of Pure and Applied Chemistry) with the help of its chemical formula.

The name given by IUPAC to Cu[(NH3)4]2+ is Tetraamine copper. Tetraammine is defined for highlighting four amino group that are attached with one copper ion. 

Cu[(NH3)4]2+ Oxidation number

Oxidation number is one of the importance characteristics, which defines the electronic excesses or deficiency in the compounds that is the gain, or loss of electron in the centre atom.

The oxidation number of Cu in Tetraamine copper is +2 as the overall complex ion has deficiency of two electrons and (NH3)4 (ammonia) compound possesses zero oxidation number.

Cu[(NH3)4]2+ Magnetic moment

Magnetic moment refers to the characteristic, which indicates the magnetic dipole moment, that is the tendency of objects or element to align with a specific amount of magnetic field.

This compound imposes paramagnetic effect. The magnetic moment of Cu[(NH3)4]2+ is 1.73 B.M. this property is reliable in imposing the fact regarding the number of n paired electron in this compound. There is a specific formula helps to calculate the number of unpaired electron.

cu[(nh3)4] 2+ lewis structure
Cu[(nh3)4] 2+ Lewis Structure from Wikipedia

The formula is number of unpaired electron = n(n+2) where N refers to the amount of magnetic moment. Therefore , this reveals that one unpaired electron present in the compound [n(n+2) = 1.73(1.73+2) = 1].

Cu[(NH3)4]2+ Shape

Shape of the compounds is revealed by calculating the number of electron present on the compounds. Electronic configuration of the compounds are reliable in reflecting the idea about the shape of the compound. The electronic configuration of Cupper in Cu[(NH3)4]2+ is  1s2 2s2 2p6 3s2 3p6 3d0 4s0. Cu shows dsp2 hybridisation with one paired electron. The compound shows square planner shape in chemistry instead of tetrahedral geometry.

Cu[(NH3)4]2+ Colour

Colour of compounds depends on the exchange of electron in the orbitals. The movement of electrons from one orbital to another can influence the oxidation number and reflects a definite to the elements of compounds.

cu[(nh3)4] 2+ lewis structure
Cu[(NH3)4]2+ colour from Wikipedia

Normally, Copper has no unpaired electron with filled D10 orbital therefore, it shows colourless appearance. In Cu[(NH3)4]2+, Copper gets an unpaired electron after the addition of ammonia and this gives a dark blue appearance to the overall ion.

Cu[(NH3)4]2+ Coordination number

Coordination n umber refers to the number of atoms coordinate or creates bonds with the other participated atom in the formation of the overall complex structure.

As four-ammonia compound, get attached with one Cu2+ ion which denotes the fact that the compound holds four coordination number. This complex ion has four strong ligands that is why it is considered as a stable coordination compound in the series.

Cu[(NH3)4]2+ Lewis structure

The number of valence electron present in Cu is 1 but in Cu2+ it becomes 9. Four NH3 compounds hold four Nitrogen atoms each of them has single lone pair after bonding with three Hydrogen molecules. Therefore, total number electrons present in four NH3 compounds are 8.

A partial sharing of electros between Cu2+ and NH3 compounds takes place to get stability. According to Lewis method of drawing, the structure of this compound Cu gets the centre position in the geometry.

The complete sketch of Lewis structure reveals that this compound creates covalent bonding as Cu is a metal and NH3 appears as a non-metal rather an Ionic compound. This structure is relevant one to represent the electronic arrangements and lack of electrons in the complex ion.

Cu[(NH3)4]2+ Reaction with HCl

Hydrochloric acid  (HCl) is a strong corrosive acid which reacts with the compounds easily. The reaction between this complex ion and HCl is kind of reaction which imposes a colour changing effect as a chemical property of the acid in reacting with ions.

HCl first gives out aqueous  solution of Tetraamine copper (II) in presence of oxygen. Then it gives excess Chlorince atom I th middle of the reaction. The balanced chemical equation is being shared below to describe its process and its cause of showing colour changing effect.

Cu[(NH3)4 (H2O)2]2+ + 4Cl = [CuCl]2- + 4NH3 + 2H2O

The Chlorine atom is added with the copper as strong presence of HCl breaks the ion. Another part of the complex ion that is NH3 (Ammonia) gets extracted from the compound. This is ligand displacement reaction as here the displacement of strong ligand Ammonia takes place in presence of strong acid.

The addition of Chloride ions with copper turns the dark blue colour of aqueous solution of Tetraamine copper (II) intro green colour. This happens due to the transition of electrons. However, after the displacement of  ammonia this change in the colour occurs Tetrachloro copper (II) complex and water molecule appear as the main product of this reaction.


This article has made a broad discussion on Tetraamine copper (II), one of the complex ion and coordination compound in Chemistry. The exceptional facts about this compound and its reaction with Hydrochloric acid have been explained in this article.

Sarnali Mukherjee

Hi.....I am Sarnali Mukherjee, a graduate from the University of Calcutta. I love to teach and share knowledge on chemistry. I have gradually gained interest in article writing since one year ago. I would love to acquire more knowledge on my subject in the future. Let's connect through LinkedIn: https://www.linkedin.com/in/sarnali-mukherjee-921b59231

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