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Calculation of magnetic moments of CoL2X2 complexes

Calculation of magnetic moments of CoL2X2 complexes. Objectives. * To explain how the mass susceptibility can be calculated.?. * To explain how the molar susceptibility can be calculated from the mass susceptibility.?.

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Calculation of magnetic moments of CoL2X2 complexes

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  1. Calculation of magnetic moments of CoL2X2 complexes

  2. Objectives * To explain how the mass susceptibility can be calculated.? * To explain how the molar susceptibility can be calculated from the mass susceptibility.? * To explain how the diamagnetic correction is carried out on xM to calculate xpara..? * To explain how the magnetic moment can be calculated.? * To predict the geometries and the spin state of the Co(II) complexes using magnetic moments.?

  3. Gouy Balance

  4. Co(2-Me-py)2(SCN)2 1 2 3

  5. Co(2-Me-py)2(SCN)2 4.2439 4 6 7 5 4.2825

  6.  (m)- (0.029  10-6 )V =  (- ) Where m = tube filled with solid – empty tube • = empty tube field on – empty tube field off • = tube filled with solid, field on – tube filled with solid, field off V = (tube filled with water – empty tube) / density of water gof standard = 16.44E-6 cgs

  7. Co(2-Me-py)2(SCN)2

  8. Calibration Constant we calculate  (calibration constant) by using m,  and Xg(mass susceptiblity )of the standard :  (m)- (0.029  10-6 )V =  (- ) X(g)= 16.44x10-6 cm3/g(emu/g)

  9.  (m)- (0.029  10-6 )V =  (- ) By using the value of  we calculate X(g) of the sample :

  10. Diamagnetic correction of magnetic susceptibility para= M - dia

  11. Relevant Pascal,s Constants

  12. Total= -1.9058x10-4 cm3/mol. AND Remember that this unit = emu/mol

  13. From this value. How can you determine the geometry and the spin state of the complex..?

  14. Octahedral Co2+ (d7) High Spin Co2+ (d7) Low Spin eg eg t2g t2g

  15. Tetrahedral Co2+ (d7) only High Spin t2 e

  16. Tetrahedral geometry

  17. The magnetic moment of tetrahedral geometry is in range(4.30 – 4.74 B.M.) and absorb light strongly at range (580-780) nm.

  18. Octahedral geometry

  19. The magnetic moment of octahedral geometry is in range(4.90 – 5.40 B.M.) and absorb light weakly in the range (640-600 nm)

  20. Co(2-Me-py)2(SCN)2 High λ Low ∆0 HS. ueff= 4.95 BM Tetrahedral (4.30-4.74 ) BM

  21. Summary 1.Magnetic moments are used to determine the spin state (high spin or low spin). 2.Octahdral complexes can be either high spin or low spin. 3.Tetrahedral complexes can only be high spin. 4.Experimental magnetic moments for Co(II) Complexes are always higher than the spin-only magnetic moments because of the significant Orbital contribution .

  22. 5.The magnitude of the orbital contribution differ for tetrahedral and octahedral ,it is greater for octahedral than for tetrahedral. Therefore ,we can distinguish between tetrahedral and octahedral. Tetrahedral; 4.30 – 4.72 B.M. Octahedral; 4.90 – 5.40 B.M.

  23. References 1- Gary L.Miessler, Donald A. Tarr, “Inorganic Chemistry”,3rd Edition, 2- D.P.Graddon ,E.C.Watton,auet.J.Chem, 1965,pp 507-520.

  24. Questions

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