`EDTA^(4-)` i9s ethylenediamine tetraacetate ion The total number of `N-CO-O` bond angles in `[Co(EDTA)]^(-1)` complex ion is .

Explanation

To solve the problem of finding the total number of N-CO-O bond angles in the complex ion \([Co(EDTA)]^{-1}\), we will follow these steps:

### Step 1: Understand the Structure of EDTA
EDTA (ethylenediaminetetraacetate) is a hexadentate ligand, meaning it can form six bonds with a metal ion. It contains two nitrogen atoms and four oxygen atoms that are part of acetate groups.

### Step 2: Draw the Structure of EDTA
- Start by drawing the backbone of EDTA, which consists of two ethylene groups (CH2-CH2) connected to two nitrogen atoms.
- Each nitrogen is bonded to an acetate group (C(=O)O^-).
- This gives us a total of four acetate groups, each contributing one oxygen atom with a negative charge.

### Step 3: Identify Coordination Sites
In the complex \([Co(EDTA)]^{-1}\):
- The two nitrogen atoms and four oxygen atoms coordinate with the cobalt ion.
- Thus, there are six coordination sites: two from nitrogen and four from oxygen.

### Step 4: Determine N-CO-O Bond Angles
- For each nitrogen atom, we can form bond angles with the cobalt and the oxygen atoms.
- Each nitrogen can form bond angles with two different oxygen atoms (one from each acetate group).

### Step 5: Count the Angles
- For one nitrogen atom:
- N-CO-O angle with the first oxygen.
- N-CO-O angle with the second oxygen.
- This gives us 2 angles per nitrogen atom.
- Since there are 2 nitrogen atoms, the total number of N-CO-O angles from both nitrogen atoms is:
\[ 2 \text{ (from one nitrogen)} + 2 \text{ (from the other nitrogen)} = 4 \text{ angles} \]

### Step 6: Total N-CO-O Angles
- Each nitrogen contributes 2 angles, leading to a total of:
\[ 4 \text{ (from both nitrogen atoms)} + 4 \text{ (from the four oxygen atoms)} = 8 \text{ N-CO-O angles} \]

### Final Answer
Thus, the total number of N-CO-O bond angles in the \([Co(EDTA)]^{-1}\) complex ion is **8**.

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