The aims of the experiment were to: (1 ) Synthesize and the is and trans isomers of (2) Perform UP-visa spectroscopy on and and report the Max and Amaze of the complexes. (3) Obtain and analyze the FT-IR spectrum of tart]CADDISH. Introduction: Molecules with identical chemical formula but different structures are known as isomers. There are different types of isomers and the focus of this experiment is on geometrical isomerism and steamrollering of octahedral complexes. Geometrical isomers of a metal complex have different spatial arrangements of the coordinated lagan’s around the metal centre.
For homiletic (MASS) and heterocyclic (MAMBA) complexes, each exhibits 2 Seibel types of isomers. Fig : Storerooms and geometrical isomers of octahedral complexes Homiletic complexes can possibly form a pair of moisteners, while heterocyclic complexes can form a pair of geometric isomers. These isomers have different physical properties and chemical properties. With reference to Fig. 1 , the homiletic octahedral complex MASS has 3 potentate lagan’s and can exist as or isomer. On the other hand, heterocyclic complex MAMMA can exist as 2 geometrical isomers, the CICS- and the trans- isomer.
In this experiment, 3 Co(all) complexes containing 2 different lagan’s delineating (en) and chloride (CLC), would be synthesized. Further analysis and characterization techniques using LLC-visa spectroscopy and FT-IR spectroscopy would then be performed on the complexes. A racemes mixture of will first be prepared from CoC12D6H20 and XIV-visa spectroscopy will be performed on it. An mentioned from this mixture would be obtained by reaction With an anagrammatically pure compound L-(+)- tartaric acid and FT-IR spectroscopy would be carried out on this mentioned.
A heterocyclic complex will be synthesized by heating Cold]AH with delimitation and concentrated HCI under a instant stream of air. Subsequently, will be dissolved in an aqueous solution and heated in a steam bath to give the trans- isomer, Experimental Procedure: Part 1: Synthesis of Racemes complexes Firstly, 3. Egg of Cocky]AH, 6. Egg of delimitation tetrachloride and a magnetic stirrer bar were added to a 50-ml beaker containing ml of De- unionized water. Ml of 40% Noah stock solution were added drowses to the suspension at regular intervals while stirring.
Subsequently, Ml of 3. 5% H2O were added drowses to the reaction mixture and was stirred for 20 minutes before heating to boiling at CHIC for 5 minutes. The reaction mixture was then taken off heat and allowed to cool undisturbed in an ice-bath for 30 minutes. Suction filtration was performed after to collect the crystals from the chilled solution The product was then washed with chilled 95% ethanol (2 x 1 ml) and followed by ethyl ether (2 x 1 Mol). The crude product was then left to dry before recording the yield. OMG of the crude product is then accurately weighed out and dissolved in denizen water in a ml volumetric flask. Denizen water was added to the volumetric flask to the mark and the LLC-visa absorption spectrum of the crude product was recorded. Art 2: Resolution of Racemes A/A-[Co(en)3]CO complexes 1 . G of crude product obtained from part 1 , 0. 81 g of L-(+)-Tartaric acid and a magnetic stirrer bar were placed in a 50-ml beaker containing ml of denizen water. ml of 10% Noah stock solution were then added drowses to the reaction mixture.
The mixture was gently stirred on a hotplate until the solids were observed to be completely dissolved. A piece of aluminum foil was then used to seal the beaker and kept in the fumed for a week. After a week, the crystals of were collected by suction filtration using a Hirsch funnel. The crystals were subsequently washed with 3 x 7 ml of chilled acetone/water of 1:1, then with 2 x ml of chilled acetone. The FT-IR absorption spectrum of was then recorded in KGB pellet form. Part 3: Synthesis of 0. G of CoC1206H20, ml of denizen water and 1 ml of delimitation were added to a glass test-tube and later immersed into a water bath with a plastic tube inserted in with the tip of the plastic tube sitting just above the solution level. An air pump was attached to the plastic tube and switched on to blow air onto the solution and the solution was heated to CHIC for 25 minutes. The pump was switched off and 1 ml of denizen water were then used to drain down the droplet hanging around the test-tube. Heating and blowing continued after until the color change of dark emerald green was observed to be complete.
The solution was then cooled to CHIC before switching off the air pump and adding 1 ml of concentrated (MOM) HCI drowses to the solution. Subsequently, the solution was heated and blown to CHIC until the volume of solution Was Observed to decrease to 0. ml. The solution was then taken off heating and blowing and left to cool in an ice bath for 5 minutes. Suction filtration was performed with a Hirsch Funnel for collection of crystals. The crystals were then washed with chilled methanol (3 x ml) before it was left to dry in air on a tissue paper.
Yield of crystals, were then recorded before accurately weighing out MGM of crystals to be dissolved in ml volumetric flask. Denizen water was added to the volumetric flask to the mark and the XIV-visa absorption spectrum of the crude product was recorded. Part 4: Commiseration reaction of 1 Omg of Hoc. AH was weighed and dissolved in a clean test tube containing ml of denizen water. The test tube was then placed in a team bath prepared from a 50-ml beaker cottoning tap water and a magnetic stirrer bar. The solution was heated until no further color change was observed.
The pink solution was then added to a ml volumetric flask and filled with water to the sums mark. The LIVE-visa absorption spectrum of the solution was recorded. Results: Complex Peak number Absorbent Max / NM Imax / mol-l dam-1 0. 378 466. 00 197. 33 2 0. 403 338. 00 21 0. 39 0. 085 609. 00 30. 24 0. 069 449. 00 24. 55 3 0. 090 400. 00 32. 03 (solution I) 0. 057 504. 00 51. 03 0. 504 307. 00 451 . 2 Table 1: Absorbent, Max and Imax of complexes ample calculations for Reran of Number of mol of x 10?5 mol = 1. 9155 x 10-3 mol dam-3 = 0. 02 0 41 7. 643 = 4. 887 Yield of crystals obtained. Amount of 0. 0129 mol Amount of enhance = = 0. 0501 mol Since Cocky]AH : enњCLC is 1 Cocky]AH is the limiting reagent. Mass of obtainable 0. 0129 x 428. 95 = 5. Egg % of yield Amount of (+)-tart H2O added 0. 005397 mol Amount of (+)Co(en)33+ added – =0. 002717 mol (Limiting reagent) Hence, Mass of obtainable = 302. 329 = 0. 82 leg % yield of = = 71. 8% Amount of Cocoa added – – =0. 00233 mol Mass of trans-[Co(en)CHIC]CHI obtainable = 0. 00233 358. 1 = 0. Egg % yield of 16. 8% Calculations for Necromantic Purity of Mass of sample used = 0. 51 leg Polarities reading = 2. 252 Concentration of sample = 0. 251 1/10 = 0. 0251 lyre Specific rotation [a]589. 3 = 89. 6854 Optical purity, pop, ([a]589. 3 / where [a]O is the optical rotation of the pure A mentioned, which is 102 a. Thus, pop= Macroeconomic purity , the % of present = pop + = 87. 9269+ = 93. 96% Thus, 93. 96% of the synthesized crystals are A isomer while the remaining 6. 04% are of the isomer Discussion & Answers to Questions: The electronic configuration of Cobalt is [Ar]sided, and in Cocoa the electronic configuration of CO(II) is [Failed.
H2O oxides co+ to give co+, which has an electronic configuration of [Ar]add. With a do configuration Co(all) complexes can exist as high spin or low spin complexes, which has an orbital habitations of spuds and DSSSL respectively. 80th habitations give rise to complexes with octahedral geometry, therefore, the Co(all) complexes formed will coordinate to six atoms. In part 1 Of the experiment, Cocoa was oxidized with H2O with ethylene dichloride as a reagent, 3 patented en lagan’s can chalet to each CO+ ion forming octahedral complex
Fig: Cobalt (Ill) complexes and (right) The balanced equation for the formation of the is as follows: 2coC12D6H20 + Ionian + H2O -9 (s) + I Orca + AH. Choral compounds are compounds that can exist as mirror images of each other but are not superimpose. Storerooms of choral compounds have the same chemical and physical properties but they rotate plane popularized light in different directions. In this experiment the metal center CO+ can coordinate with 3 patented (en) lagan’s, forming a racemes mixture of A[Co(en)3]3+ and as shown in Fig. 1. Therefore, Co(all) is suitable for making choral compounds.
Furthermore, due to the high charge density that CO+ possess, it is considered a relatively hard acid while en containing N atoms, is considered a hard base. Based on Person’s Hard-Soft Acid Base Theory, Co(all) would have a high affinity for en. Moreover, octahedral complexes of Co(all) are more stable than Co(all) complexes especially when coordinated with en lagan’s. Based on the spectrographically series, where – A strong field liking would result in a splitting of the d orbital with a greater extent of splitting energy, Since the splitting energy is large and is greater than the pairing energy of electrons, it would be more energetically feasible for the electrons to pair up in the degenerate tag orbital, thus, a low spin complex would be more favorable. Furthermore based on the transition metal series, PDP > cue > In > co > Zen > Mn > MGM Co has a relatively high stability with delimitation lagan’s, hence, liking exchange is less likely and the moisteners of can be resolved.
Choral resolution is the process of separating racemes compounds into their moisteners. As discussed earlier, moisteners have identical chemical and physical properties, therefore physical separation techniques alone are not sufficient to isolate moisteners. In this experiment, an anagrammatically pure compound, acid was added to the racemes mixture of MA, L-(+)-tartaric acid is depredation by the base, which then acts as a counter anion to each mentioned. As a result, 2 toastmasters are formed which have different physical and chemical properties. ј- is less soluble than therefore, it recitalists first from the mixture. By performing suction filtration on the suspension, crystals of can be isolated from – which remains in the filtrate. FT-IR spectroscopy was carried out on after the crystals were dried. With reference to literature IR spectrum of L-(+)-tartaric acid, the sharp and intense peak observed at 3495. CACM-1 Of the spectrum Of could be due to free O-H bond stretch of the treated present in The peak at 3466. CACM could be assigned to the carboxylic O-H bond stretch, which also belongs to the treated.
Within the characteristic group region there were also two other sharp and strict peaks, at 3208. CACM-1 and 3090. CACM-1. These peaks could be assigned to the symmetric and asymmetric stretching of the N-H bond in the delimitation lagan’s. The balanced equation in Part 3 is given below: 4C0C1206H20 + + 02 + CLC 4 + AH The disinterested of can be distinguished by FT-IR spectroscopy, as although they contain identical functional groups, each disinterested has slight shifts in the bands, and these spectral differences leads to a different fingerprint region within the spectrums.
In part 3 and 4 of the experiment, geometrical isomers of were synthesized. The Rene crystals of is the trans isomer, and its PUPAS name is trans-dichloride(delimitation)cobalt(all) chloride (trans- In part 4 of the experiment, underwent an commiseration reaction to give a pink solution which contained CICS- dichloride(delimitation)cobalt(all) chloride (CICS-[Co(en)CHIC]CLC). Fig. 3: Cationic geometrical isomers of complex Trans- [Co(en)CHIC]CLC is the kinetic product of the reaction in part 3; it is favored as the strongly bound chloride lagan’s exert a strong trans-directing influence on the liking directly across.
Hence, the chloride lagan’s would have en sands in trans fashion preferentially, forming Although Co(all) complexes are generally stable, they are susceptible to hydrolysis. In solution, water may replace one of the more labile liking CHI giving a mixture Of CICS- and With prolonged heating, the thermodynamic CICS-isomer would be formed. Structures of geometrical and optical isomers of Co(ugly)3, where ugly = NACHOS : Crystal Field Theory is a model that can explain the non-degeneracy’s of the d orbital, which is useful in analyzing and describing the XIV-visa absorption spectrum of the complexes.
In an octahedral field, when lagan’s approach the teal ion, the electrons from the lagan’s orbital will be closer to the adz and DXL-y orbital resulting in the splitting of d orbital to 2 energy levels. adz and DXL orbital being closer to liking orbital experience stronger electronic repulsion and are thus higher in energy. These orbital are collectively known as egger while the other 3 d orbital are degenerate, at a lower energy level and are collectively known as tag. Electrons can be excited to the next higher energy level (egg. From tag to egg) by absorbing photons of visible light.
The wavelength of light absorbed would depend on the energy gap of the d-d ruinations, which also corresponds to the Crystal field stabilization energy and explains the colors of the complexes. Two factors affect the energy gap of the non-degenerate d orbital. One, stronger field lagan’s such as en cause a greater splitting of the d orbital of CO+, which creates a larger energy gap and in turn favors a low spin complex. Secondly, heterocyclic complexes such as experiences the John-teller effect, whereby the octahedral field of the complex is distorted by a compression or elongation along the z-axis.
The degenerate orbital undergo further splitting, changing he energy gap between orbital. Fig. 4: Wavelength and corresponding absorbed and transmitted colors of visible light has 2 absorption peaks, one at 466. NM and another at 338. NM. 338. NM is beyond the range of visible light spectrum, however 466. NM corresponds to the wavelength of blue light. Thus, the complementary color of blue, yellow light, is transmitted. The observed color of the crystals was light orange, which is similar to the expected color of the complex. Has absorption peaks at 400. Moon, 449. NM and 609. NM.
These wavelengths corresponds to violet, blue and range, and the complementary colors are yellow-green, yellow and greenish-blue respectively. The mixing of these colors likely to result in a shade of green, which explains the observed color of the complex. The I-JP- visa spectrum of solution I shows 2 peaks, a sharp peak at 307. NM and a gentle peak at 504. NM. 307. NM is beyond the range of visible light spectrum, while 504. NM corresponds to the wavelength of green light absorbed. With reference to Fig. 4, the complementary color absorbed would be red-purple. However, the observed color of the solution was pink.
This loud be due to the diluted nature of the solution resulting in pink being observed instead. Fig 5: Transitions for Imax Being psychometric, Elaborate rule states that there must be a change in parity for such molecule. Only grade to angered transitions are allowed. Thus, all d to d transitions are forbidden by this selection rule. From the table, has a Imax of 197. 33 mol-l dam at 466. NM and 210. 39 mol-dumdum-1 at 338. NM. Thus, it can be concluded that the transition was Loretta-allowed d to d transition. Trans- possesses a centre of inversion making it a psychometric molecule.