OP-II-3

PP-I-55effects, are energetically close. The deep endoeffet on the DTA curve at 600°Ccorresponds to the destruction of the iron sulfate FeSO 4 formed to Fe 2 O 3 .The valent - fluctuations ν as in the IR spectrum at the frequency range of 1050 -1170 sm –1 of the thermolysis products correspond to the fluctuations of SO 2– 4 groupthat twestify the oxidation of sulfone group of thiol to SO 2– 4 and formation of sodiumsulphate absorption bond at 1000 sm –1 in the IR spectrum of destruction products.The absorption bonds at 600-635 sm –1 correspond to the sulfide formation. Thus, thechemical mechanism thermal destruction of unithiol complex of iron studied by DTA,IR-spectroscopic and X-ray phase analysis is represented by the following scheme:78−160Na 2 [FeL 2 H 2 O]H 2 O ⎯⎯ ⎯⎯° С160−285⎯→Na 2 [FeL 2 H 2 O]+Н 2 О ⎯⎯ ⎯⎯° С⎯→Na 2 [FeL 2 ]+Н 2 О ⎯ 400°С ⎯⎯ →Na 2 SO 4 +FeS+6СО 2 ↑+Н 2 О+4H 2 S↑ ⎯ 440 ⎯°С→ FeSO 4 ⎯ 600 °С ⎯⎯ → Fe 2 O 3 +(SO 2 , SO 3 , О 2 )↑The kinetic parameters of activation process of dehydration of iron complex areNa 2 [FeL 2 H 2 O] H 2 O are represented in table 1.Table 1 - The kinetic characteristics of the thermal decomposition of the iron complexComplexTm, °CEa,kJ/mollg A0,с –1ln k ,≠- ΔS ,с –1 J/mol·К≠ΔH ,kJ/molNa 2 [FeL 2 H 2 O]H 2 O 10035,112,01,7155,132,02408,44,12,6233,34,144016,385,412,59231,4210,5860063,7112,53,72172,2656,45The dehydration reaction of these complexes is developed by steps. Values Theactivation energy (E a ) values are essentially decreased for waterless complex,namely from 35,1 to 8,4 kJ/mol. The separation of molecule under water heatingconditions the weakness of some bonds in the complex that leads the further processwith smaller energy of activation. Value of a speed constant of dehydrotation reactionof speed lnk is increased from 1,7 to 2,6 c –1 .By consideration enthalpy (∆H ≠ ) and entropy (∆S ≠ ) of activation values one canconclude, that enthalpy and entropy factors for waterless complexes compensateeach other and probably compensatory effect in the kineticl process can beobserved.317