The coordination number and the oxidation state of the element E in the complex [E(en)_2(C_2O_4)]NO_2 (where (en) is ethylene diamine) are respectively:

A) 4 and 3

B) 6 and 3

C) 6 and 2

D) 4 and 2

To determine the coordination number and oxidation state of the element E in the complex [E(en)₂(C₂O₄)]NO₂, we need to analyze the components of the complex step by step.

Understanding Coordination Number

The coordination number refers to the number of ligand atoms that are directly bonded to the central metal atom or ion. In this complex, we have two types of ligands: ethylene diamine (en) and oxalate (C₂O₄^2-).

Identifying the Ligands

• Ethylene diamine (en): This is a bidentate ligand, meaning it can attach to the metal at two points. Since there are two en ligands, they contribute a total of 4 coordination sites (2 from each ligand).
• Oxalate (C₂O₄^2-): This is also a bidentate ligand, contributing an additional 2 coordination sites.

Calculating the Total Coordination Number

Adding these together gives us:

• 4 (from 2 en ligands) + 2 (from 1 oxalate ligand) = 6

Thus, the coordination number of element E is 6.

Determining Oxidation State

Next, we need to find the oxidation state of element E. The overall charge of the complex must be balanced with the charges of the ligands and the counter ion (NO₂^-).

Analyzing Charges

• The charge of the oxalate ion (C₂O₄^2-) is -2.
• The charge of each ethylene diamine (en) is neutral (0).
• The nitro ion (NO₂^-) has a charge of -1.

Setting Up the Equation

Let the oxidation state of E be x. The overall charge of the complex can be expressed as:

x (oxidation state of E) + 0 (from en) - 2 (from C₂O₄^2-) - 1 (from NO₂^-) = 0

Rearranging this gives us:

x - 3 = 0

Thus, x = +3.

Final Summary

From our analysis, we find that the coordination number of element E is 6, and its oxidation state is +3. Therefore, the correct answer is:

B) 6 and 3