The following questions refer to reaction of N-methylsalicylaldimine. Ensure you answer all parts (a) - (h). The reaction of N-methylsalicylaldimine (salH, see structure) with NiCl2.6H2O produces a blue precipitate with composition [Ni(sal)2]. {Ni = [Ar] 4s2 3d7} (a) Write a fully balanced equation for this reaction. (2 marks) (b) The ligand deprotonates before it coordinates. Where does it deprotonate? (1 mark) (c) What is the oxidation state of nickel in the complex? (1 mark) (d) What is the number of d-electrons left on the nickel centre? (1 mark) (e) Give the donor atoms that the ligand uses to coordinate to nickel? (1 mark) (f) What is the coordination number of the nickel centre? (1 mark) (g) Ni(sal)2 is a diamagnetic complex. Draw the structure, clearly indicating the geometry. (2 marks) (h) Are cis- and trans- isomers possible for the geometry that you have chosen? (1 mark) In the e-exam you will have the following information below the question. "Please answer question on your blank piece of paper. After your exam finishes, you’ll have extra time to access your phone to scan a QR code and upload your answer. Clearly label each page with Student ID and this question number (and sub part if applicable) (for example, 'Question 7a') Do not write your Name on it"

Question

The following questions refer to reaction of N-methylsalicylaldimine. Ensure you answer all parts (a) - (h). The reaction of N-methylsalicylaldimine (salH, see structure) with NiCl2.6H2O produces a blue precipitate with composition [Ni(sal)2]. {Ni = [Ar] 4s2 3d7} (a) Write a fully balanced equation for this reaction. (2 marks) (b) The ligand deprotonates before it coordinates. Where does it deprotonate? (1 mark) (c) What is the oxidation state of nickel in the complex? (1 mark) (d) What is the number of d-electrons left on the nickel centre? (1 mark) (e) Give the donor atoms that the ligand uses to coordinate to nickel? (1 mark) (f) What is the coordination number of the nickel centre? (1 mark) (g) Ni(sal)2 is a diamagnetic complex. Draw the structure, clearly indicating the geometry. (2 marks) (h) Are cis- and trans- isomers possible for the geometry that you have chosen? (1 mark) In the e-exam you will have the following information below the question. "Please answer question on your blank piece of paper. After your exam finishes, you’ll have extra time to access your phone to scan a QR code and upload your answer. Clearly label each page with Student ID and this question number (and sub part if applicable) (for example, 'Question 7a') Do not write your Name on it"

BlackTom AI · Accepted Answer

(a) The balanced equation for the reaction is: NiCl2·6H2O + 2 salH → [Ni(sal)2] + 2 HCl + 6 H2O. Here, N-methylsalicylaldimine (salH) acts as a ligand that coordinates with nickel after deprotonation.

(b) The ligand deprotonates at the phenolic OH group. This deprotonation is crucial as it allows the oxygen atom to act as a donor atom in coordination with the nickel ion.

(c) The oxidation state of nickel in the complex [Ni(sal)2] is +2. This is because the NiCl2·6H2O provides Ni in the +2 oxidation state, and the ligand salH is neutral after deprotonation.

(d) The number of d-electrons left on the nickel center is 8. Nickel in the +2 oxidation state has the electron configuration [Ar] 3d8, as it loses the two 4s electrons.

(e) The donor atoms that the ligand uses to coordinate to nickel are the phenoxide oxygen (O) and the imine nitrogen (N). These atoms form a stable chelate ring with the nickel center.

(f) The coordination number of the nickel center is 4. This is due to the two bidentate ligands (sal) providing four donor atoms (2 N and 2 O) to the nickel.

(g) The structure of [Ni(sal)2] is square planar, which is typical for d8 metal centers like Ni(II) in a low-spin configuration. The geometry is stabilized by the chelating nature of the sal ligands.

(h) Cis- and trans- isomers are not possible for the square planar geometry of [Ni(sal)2]. Square planar complexes with bidentate ligands do not exhibit cis/trans isomerism due to the fixed arrangement of donor atoms around the metal center.

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