[NiCl₂(PPh₃)₂] is named as:
Dichloridobis (triphenyl phosphine) nickel (II)
Understanding Coordination Complex Nomenclature
Coordination complexes are formed when a central metal atom or ion is bonded to a surrounding array of molecules or ions, known as ligands. Naming these complexes follows specific rules established by the International Union of Pure and Applied Chemistry (IUPAC).
Analyzing the Coordination Complex [NiCl₂(PPh₃)₂]
The given complex is [NiCl₂(PPh₃)₂]. Let's break down its components:
- Central Metal Ion: Ni (Nickel)
- Ligands:
- Cl: Chloride (anionic ligand, charge -1)
- PPh₃: Triphenyl phosphine (neutral ligand)
- Number of Ligands:
- Two chloride ligands (Cl₂)
- Two triphenyl phosphine ligands ((PPh₃)₂)
- Overall Charge: The complex is enclosed in square brackets but does not show an overall charge outside, indicating it is a neutral complex.
Calculating the Oxidation State of Nickel
To name the complex correctly, we need to determine the oxidation state of the central nickel ion. Let the oxidation state of Ni be &(\text{x}&). The charge of a chloride ligand (&(\text{Cl}^-}&) is -1. The charge of the triphenyl phosphine ligand (&(\text{PPh}_3}&) is 0 (neutral).
The sum of the oxidation states of the central metal and the charges of the ligands equals the overall charge of the complex. For a neutral complex, this sum is zero.
\(\text{x} + 2 \times (\text{-1}) + 2 \times (\text{0}) = 0\)
\(\text{x} - 2 + 0 = 0\)
\(\text{x} = +2\)
So, the oxidation state of Nickel in this coordination complex is +2, denoted as Nickel(II).
Applying IUPAC Rules for Naming Coordination Complexes
Now, let's apply the IUPAC rules to name [NiCl₂(PPh₃)₂]:
- Ligands are named first, followed by the metal.
- Ligands are listed in alphabetical order. The anionic ligand 'chloride' becomes 'chlorido' or 'chloro'. The neutral ligand 'triphenyl phosphine' keeps its name. Alphabetically, 'chlorido' comes before 'triphenyl phosphine'.
- Use prefixes to indicate the number of ligands. 'di-' for two chlorides. For triphenyl phosphine, which is a complex ligand name, use 'bis-' for two, and enclose the ligand name in parentheses.
- The name of the central metal atom (Nickel) follows the ligand names.
- Since the complex is neutral, the oxidation state of the metal is indicated in Roman numerals in parentheses after the metal name. Nickel is in the +2 oxidation state, so it is Nickel(II).
Following these steps:
- Ligands: Two chlorido, Two triphenyl phosphine.
- Alphabetical order: dichlorido, bis(triphenyl phosphine).
- Metal: nickel.
- Oxidation state: (II).
Combining these parts gives the name: dichlorido bis(triphenyl phosphine) nickel(II).
Evaluating the Options
Let's compare our derived name with the given options:
- Option 1: Dichloridobis (triphenyl phosphine) nickel (II) - This exactly matches the name we derived using IUPAC rules. The anionic ligand 'chloride' is correctly named 'dichlorido', 'triphenyl phosphine' is a complex ligand so 'bis' is used and it's enclosed in parentheses, followed by the metal 'nickel' and its oxidation state '(II)'.
- Option 2: Nickel chlorido bis (triphenyl phosphine) - The metal 'Nickel' is named first, which is incorrect in IUPAC nomenclature for neutral or cationic complexes. Ligands should be named before the metal.
- Option 3: Diphenyl phosphine Nickel (II) chloride - The ligand name is incorrect (Diphenyl phosphine instead of Triphenyl phosphine). Also, the overall structure of the name does not follow the standard coordination complex naming conventions.
- Option 4: Dichlorobis (Diphenyl phosphine) Nickel (II) - The ligand name is incorrect (Diphenyl phosphine instead of Triphenyl phosphine).
Based on the IUPAC naming conventions for coordination complexes, Option 1 correctly names the complex [NiCl₂(PPh₃)₂].
| Component | Identity | Number | IUPAC Name | Prefix | Full Ligand Name |
|---|---|---|---|---|---|
| Ligand 1 | Cl⁻ | 2 | chlorido | di- | dichlorido |
| Ligand 2 | PPh₃ | 2 | triphenyl phosphine | bis- | bis(triphenyl phosphine) |
| Metal | Ni | 1 | nickel | - | nickel |
| Oxidation State | Ni | +2 | (II) | - | (II) |
Putting it all together (Ligands in alphabetical order followed by Metal and oxidation state): dichlorido bis(triphenyl phosphine) nickel(II).
Revision Table: Key IUPAC Naming Points for Coordination Complexes
| Rule Aspect | Description | Example for [NiCl₂(PPh₃)₂] |
|---|---|---|
| Order | Ligands before metal. | Chlorido, Triphenyl phosphine before Nickel. |
| Ligand Alphabetization | Ligands listed alphabetically by name (ignoring prefixes). | 'chlorido' before 'triphenyl phosphine'. |
| Anionic Ligand Naming | Add '-o' (e.g., chloride → chlorido). | Chloride becomes chlorido. |
| Neutral Ligand Naming | Usually named as the molecule (exceptions like aqua, ammine). | Triphenyl phosphine remains triphenyl phosphine. |
| Number Prefixes | di-, tri-, tetra- for simple ligands; bis-, tris-, tetrakis- for complex ligands or those with existing prefixes (name in parentheses). | di- for two chlorides; bis- for two triphenyl phosphines (as PPh₃ is complex). |
| Metal Name | Used as is for cationic/neutral complexes. Add '-ate' for anionic complexes. | Nickel (neutral complex). |
| Oxidation State | Shown in Roman numerals in parentheses after the metal name for cationic/neutral/anionic complexes. | (II) as Nickel is in +2 oxidation state. |
Additional Information on Coordination Chemistry Naming
Coordination complex nomenclature is a systematic way to name these compounds based on their composition. The square brackets [ ] in the formula [NiCl₂(PPh₃)₂] denote the coordination sphere, which includes the central metal atom and its ligands. The counter ions, if any, would be written outside the brackets.
Ligands can be classified based on their charge (anionic, neutral, cationic) and how many donor atoms they use to bind to the metal (monodentate, bidentate, polydentate). Chloride (&(\text{Cl}^-}&) is a monodentate anionic ligand. Triphenyl phosphine (&(\text{PPh}_3}&) is a monodentate neutral ligand, donating through the phosphorus atom.
Understanding the charge of ligands is crucial for determining the oxidation state of the central metal atom, which is a key part of the complex's name.
Important Questions from Coordination Compounds
Match List-I with List-II:
List-I List-II (A) Diamagnetic solid (I) CrO₂ (B) Ferromagnetic solid (II) Fe₃O₄ (C) Antiferromagnetic solid (III) NaCl (D) Ferrimagnetic solid (IV) MnO Choose the correct answer from the options given below:
Inner orbital complex among the following is:
(A) [Co(NH₃)₆]³⁺
(B) [CoF₆]³⁻
(C) [Ni(CN)4]²⁻
(D) [MnCl₆]³⁻
(E) [FeF₆]³⁻
Choose the correct answer from the options given below:
Which will form the most stable complex?
How many Cr-O bonds in dichromate ions are of the same bond length and are in resonance?
Which of the following statement is/are correct for complex [NiCl4]2-?
(A) Ni has oxidation state +2
(B) Cl is a weak field ligand
(C) Compound is paramagnetic
(D) dsp2 hybridisation
(E) Low spin complex
Choose the correct answer from the options given below:
