Coordination Compounds — MHT-CET Chemistry

Formulas (2)

• Denticity and Counting Donor Atoms · Donor-atom count
  $$\text{donor atoms} = \sum (\text{number of ligands} \times \text{denticity});\quad \text{EDTA} = 6,\ \text{ox} = \text{en} = 2$$
• Field Strength: the Spectrochemical Series · Spectrochemical series
  $$\text{I}^- < \text{Br}^- < \text{S}^{2-} < \text{SCN}^- < \text{Cl}^- < \text{F}^- < \text{OH}^- < \text{C}_2\text{O}_4^{2-} < \text{H}_2\text{O} < \text{NH}_3 < \text{en} < \text{CN}^- < \text{CO}$$

Reference tables (1)

Watch out for (3)

• Counting all four oxygens of oxalate
  → Denticity and Counting Donor Atoms
• Reading carbonyl or carbonato by the 'carbon'
  → Neutral and Anionic Ligands by Name
• Ranking by charge
  → Field Strength: the Spectrochemical Series

Formulas (1)

• Same Ligands or Mixed, and the Charge on the Sphere · Sphere charge
  $$\text{charge on sphere} = \text{oxidation state of metal} + \sum \text{ligand charges}$$

Watch out for (1)

• Calling a salt 'neutral' because the whole compound is
  → Same Ligands or Mixed, and the Charge on the Sphere

Formulas (3)

• Oxidation State and Coordination Number · Oxidation state and coordination number
  $$x + \sum q_{\text{ligand}} = q_{\text{sphere}};\qquad \text{CN} = \sum (\text{ligands} \times \text{denticity})$$
• Counter Ions: What Precipitates with Silver Nitrate · Werner's precipitation count
  $$n(\text{AgCl}) = n(\text{Cl}^- \text{ outside } [\ ])\ \text{per mole of complex}$$
• From Name to Formula and Back · Name to formula
  $$q_{\text{sphere}} = \text{(Roman numeral)} + \sum q_{\text{ligand}};\quad \text{counter ions} \times \text{their charge} = -q_{\text{sphere}}$$

Watch out for (5)

• Counting ligands instead of donor atoms
  → Oxidation State and Coordination Number
• Reading -ous and -ic backwards
  → Oxidation State and Coordination Number
• Counting every chlorine in the formula
  → Counter Ions: What Precipitates with Silver Nitrate
• Ordering ligands by charge or by prefix
  → From Name to Formula and Back
• Dropping the -ate or the oxidation state
  → From Name to Formula and Back

Formulas (1)

• Geometric (cis–trans) Isomerism and the MA₂BC Type · Square planar geometric isomers
  $$\text{MA}_4, \text{MA}_3\text{B}: 0;\quad \text{MA}_2\text{B}_2, \text{MA}_2\text{BC}: 2 \ (\textit{cis}, \textit{trans});\quad \text{MABCD}: 3$$

Reference tables (1)

Watch out for (2)

• Calling a water swap 'ionisation'
  → The Four Structural Isomerisms
• Reading MA₂B₂ as MA₂BC
  → Geometric (cis–trans) Isomerism and the MA₂BC Type

Formulas (4)

• Hybridisation and Geometry from d Electrons and Field Strength · Hybridisation by coordination number
  $$\text{CN } 2: sp;\quad \text{CN } 4: sp^3 \text{ (tetrahedral)},\ dsp^2 \text{ (square planar)};\quad \text{CN } 6: d^2sp^3 \text{ (inner)},\ sp^3d^2 \text{ (outer)}$$
• Unpaired Electrons and the Spin-Only Magnetic Moment · Spin-only magnetic moment
  $$\mu = \sqrt{n(n+2)}\ \text{BM}$$
• Effective Atomic Number (EAN) · EAN
  $$\text{EAN} = Z - x + 2\,\text{CN}$$
• Stability of Complexes: Metal Charge and the Irving–Williams Order · Irving–Williams order (same ligand)
  $$\text{Cu}^{2+} > \text{Ni}^{2+} > \text{Co}^{2+} > \text{Fe}^{2+} > \text{Mn}^{2+} > \text{Cd}^{2+}$$

Watch out for (4)

• Calling every four-coordinate complex tetrahedral
  → Hybridisation and Geometry from d Electrons and Field Strength
• Using the free-ion count for a strong-field complex
  → Unpaired Electrons and the Spin-Only Magnetic Moment
• Adding one electron per ligand, or per bidentate ligand
  → Effective Atomic Number (EAN)
• Ranking by atomic number
  → Stability of Complexes: Metal Charge and the Irving–Williams Order