Nickel complex from Schiff base ligand free essay sample

We perform two separate reactions in this experiment in order to obtain Schiff Base Ligand that will substitute the ligands of a nickel hydrated complex. Like the majority of the common transition metals, during the reaction of nickel metal reaction, nickel metals tend to form an ion with a charge of 2+. This helps it to form complexes because of the empty orbitals it has around it. This nature of the metals allows it to bond with compounds through lone pairs, which is scientifically known as the dative bonding. On the second part of this experiment we react the Schiff base ligand with hydrated nickel complex, this will allow us to form new nickel complex which is known as. We do this through condensation and substitution from the hydrated nickel complex. Results and discussion During the mixing of pyrrole-2-aldehyde with ethanol and 1,3-diaminopropane we obtain a colourless solution. As it is being heated under reflux, colour change is observed, the solution starts to change into orange-red solution. This is due to the fact that nickel ions are being suspended in the solution. After 4 minutes of heating under reflux, we finally cool it for 1 hour 30 minutes in ice bath, after this period of time yellow crystals start to form at the bottom of the round bottomed flask. After the filtering of these crystals, the remain yellow and after being rinsed with diethyl ether they change into a light yellow colour. We than dissolve these crystals in warm ethanol and the resultant solution turns slightly yellow. The solution immediately turns brick red because of the precipitate that is present, suspended in the solution. The solution remains brick red after the addition of the the sodium carbonate, but as I stir the precipitate intensifies. The first filtered crystals are pasty. When i redissolve them in dichloromethane they form a cleared solution. Using the rotary evaporator to evaporate the dichloromethane and petroleum ether we obtain dark red crystals. Percentage yield of Schiff base ligand: Pyrrole-2aldehyde Molar mass= 14+16+(12. 015)+(1. 0085) =95. 09 g. mol-1 n = = =9. 9910-3 mol 1,3-diaminopropane Molar mass=(142)+(1. 00810)+(12. 013) =74. 11 g. mol-1 density = 0. 88=m= 0. 352g n = = =4. 7510-3 mol Therefore the ratios: Pyrrole-2-aldehyde : 1,3-diaminopropane 2:1 9. 9910-3: x x = 4. 99510-3 mol Table1: Theoretical mass calculations of the Schiff Base Ligand Moles Pyrrole-2-aldehyde 1,3-diaminopropane Schiff Base Ligand Initial moles 9. 99? 10-3 4. 75? 10-3 0 Reacted moles 4. 75? 10-3 4. 75? 10-3 0 Moles produced or left 5. 293? 10-3 0 4. 75? 10-3 So we have 1,3-diaminopropane as our limitin g reagent. Thus the theoretical yield is: Molar mass of Schiff Base Ligand= 228. 298g/mol Mass= No. of moles ? molar mass =4. 75? 10-3? 228.298 =1. 08g Thus the percentage yield: Actual mass = 0. 767g %yield = = =71. 01% The theoretical and percentage yield of Nickel (II) Complex from Schiff Base Ligand Nickel acetate Molar mass= (168)+(124)+(1. 00814)+58. 69 =200. 802 g. mol-1 n = = =2. 4910-3mol Schiff base ligand Molar mass=(1213)+(1. 00816)+(144) =228. 128 g. mol-1 n = = =1. 5810-3mol Therefore the ratios: Nickel acetate : Schiff base ligand 1:1 2. 4910-3 : x X = 2. 4910-3 mol Thus the limiting reagent is Schiff base ligand Table1: Theoretical mass calculations of the nickel complex Moles Nickel acetate Schiff base ligand Nickel complex Initial moles 2. 49? 10-3 1. 58? 10-3 0 Reacted moles 1. 58? 10-3 1. 58? 10-3 0 Moles produced or left 9. 1? 10-4 0 9. 1? 10-4 Molar mass of nickel complex= 284. 972g/mol Mass= No. of moles ? molar mass =9. 1? 10-4? 284. 972 =0. 26g Thus the percentage yield: Actual mass = 0. 1g %yield = = =38. 46% Note: from left to right on the spectrum signal ? (ppm) Intergral Multiplicity Assignment 1 9. 83 2 Broad singlet A 2 8. 03 2 Singlet B 3 6. 85 2 Singlet C 4 6. 46 2 Doublet D 5 6. 22 2 Triplet E 6 3. 62 4 Triplet F 7 1. 98 2 Pentet G Table 1: results from the spectrum of the Schiff base ligand. signal ? (ppm) Intergral Multiplicity Assignment 1 6. 9 2 Triplet E 2 6. 6 2 Doublet D 3 6. 1 2 Singlet C 4 3. 2 4 Triplet B 5 1. 8 1 Quintet A 6 1. 5 1 Quintet A 7 7. 2 2 Doublet F Table 2: results from the spectrum of the nickel complex Schiff Base ligand + [Ni(OCOH)2 Â · 4H2O] Nickel complex Ni(OCOCH3)2. 4H2O + C13H16N4 [Ni(C13H14N4)] + (CH3COOH)2 + 4H2O This implies that the Schiff Base ligand and the Nickel complex have a 1 : 1 ratio in the reaction. The structure of the product that forms is: 2. So we can classify the Schiff Base ligand as tetradentate ligand because one ligand donates four lone pairs to the nickel ion. Thus the nickel ion has a coordinate number of four, which constitute the square planar shape, nickel being bonded to the Nitrogens that have the lone pairs to fill the empty shell of the nickel ion. 3. On the Schiff base ligand, we get a spectrum that has 7 signals because of the extra hydrogens bonded to nitrogens compared to the nickel complex but on the nickel complex, we get 6 signals because the hydrogens that were bonded to the nitrogens were removed during the chelation.4(a). 4(b). 4(c). 5. Conclusion Thus it is visible that how much nickel complex we have, depends on how much Schiff base ligand we have. The more Schiff base ligand we produce, the more possible it is to obtain higher yield of nickel complex, since they react on a 1 : 1 ratio. The yield of the Schiff base ligand was 0. 36g and from this ligand 0. 1g of nickel complex was yielded using 0. 5g of nickel acetate.